A cognitive function evaluation system based on blood pressure and cerebral oxygen monitoring

Abstract

The application discloses a cognitive function evaluation system based on blood pressure and cerebral blood oxygen monitoring, which comprises a collection module, a calculation module and an evaluation result calculation module, wherein the collection module is used for synchronously collecting left and right prefrontal cerebral blood oxygen data and continuous arterial blood pressure data; the calculation module is used for calculating the average value of cerebral blood oxygen saturation, the coupling strength value of left and right prefrontal cerebral blood oxygen and the coupling strength value of cerebral blood oxygen and blood pressure in the collection period; and the evaluation result calculation module is used for evaluating the cognitive function of the subject according to the calculated average value of cerebral blood oxygen saturation, the coupling strength value of left and right prefrontal cerebral blood oxygen and the coupling strength value of cerebral blood oxygen and blood pressure; when the average value of dominant side prefrontal cerebral blood oxygen saturation is greater than 60%, the subject is judged as normal cognition; when 56% is less than or equal to the average value of dominant side prefrontal cerebral blood oxygen saturation, the subject is judged as possible mild cognitive impairment; and when the average value of dominant side prefrontal cerebral blood oxygen saturation is less than 56%, the subject is judged as possible severe cognitive impairment.

Description

[0001] This application is a divisional application of the invention patent application with application number "202210562941.9", application date May 23, 2022, and invention title "A Cognitive Function Assessment Method and System". Technical Field

[0002] This invention relates to the field of biosignal detection, and more particularly to a cognitive function assessment system based on blood pressure and cerebral oxygenation monitoring. Background Technology

[0003] With the aging of the global population, the prevalence of Alzheimer's disease is gradually increasing, seriously affecting the quality of life of the elderly. While the progression of Alzheimer's disease is irreversible, cognitive decline often begins long before the onset of the disease. Early detection and assessment of cognitive function can help identify cognitive impairment at an early stage, allowing for early prevention and intervention, delaying or even reversing its development, and effectively reducing the incidence of Alzheimer's disease. Currently, cognitive function assessments mainly rely on scales, which are time-consuming, subjective, and dependent on professional assessors. This poses a challenge for elderly care institutions and communities lacking professional assessors to conduct cognitive impairment screenings. Therefore, there is a strong need for a simple, easy-to-use, objective, and quantifiable assessment system for screening.

[0004] Therefore, this invention provides a cognitive function assessment method and system that can conveniently and accurately assess cognitive function and detect cognitive impairment at an early stage, and has broad application prospects in the field of health monitoring. Summary of the Invention

[0005] To achieve the objectives of this invention, the following technical solution is adopted: A cognitive function assessment system includes a data acquisition module, a calculation module, and an assessment result calculation module. The data acquisition module is used to simultaneously acquire cerebral oxygenation data from both sides of the prefrontal cortex and continuous arterial blood pressure data. The calculation module is used to calculate the average cerebral oxygen saturation, the coupling strength of cerebral oxygenation in both sides of the prefrontal cortex, and the coupling strength between cerebral oxygenation and blood pressure during the data acquisition period. The assessment result calculation module is used to assess the subject's cognitive function based on the calculated average cerebral oxygen saturation, the coupling strength of cerebral oxygenation in both sides of the prefrontal cortex, and the coupling strength between cerebral oxygenation and blood pressure.

[0006] The cognitive function assessment system includes a data acquisition module comprising an arterial blood pressure acquisition module, a cerebral blood oxygen acquisition module, and a blood pressure-cerebral oxygen synchronization triggering module.

[0007] The cognitive function assessment system includes a blood pressure-brain oxygen synchronization triggering module that controls the arterial blood pressure acquisition module and the brain blood oxygen acquisition module to simultaneously acquire brain blood oxygen data and continuous arterial blood pressure data from both sides of the frontal lobe.

[0008] The cognitive function assessment system includes a calculation module comprising a blood oxygen saturation calculation module, a coupling strength calculation module, and a blood flow parameter calculation module.

[0009] The aforementioned cognitive function assessment system, wherein the blood oxygen saturation calculation module calculates the average cerebral blood oxygen saturation in the following manner: ,

[0010] Among them, R mean R represents the average cerebral oxygen saturation, N is the number of sampling points within the measurement time period, f is the sampling rate, and R0 is the average value. i Let be the blood oxygen saturation value at the i-th sampling point.

[0011] The cognitive function assessment system, wherein the coupling strength calculation module calculates the brain oxygenation coupling strength values ​​of the left and right prefrontal lobes as follows: Based on the brain oxygenation hemoglobin concentration change data of the left and right prefrontal lobes during a 10-minute data collection period in a resting state, the effect connectivity strength of the left and right prefrontal lobes in the 0.05–0.15 Hz frequency band is calculated. Specifically, the brain oxygenation signals of the two channels of the left and right prefrontal lobes are labeled as i and j, respectively. First, the phase information of the brain oxygenation hemoglobin concentration change signal in the 0.05–0.15 Hz frequency band is extracted by wavelet transformation. Based on this, a coupled phase oscillation model of the brain oxygenation hemoglobin concentration change signal of the two channels is constructed. A likelihood function is constructed based on Bayesian inference. The coupling coefficient of the two-channel phase coupling model is inferred by calculating the stable point of the negative log-likelihood function through recursive operation. Then, the coupling strength of the i to j channel is calculated. for: , K =2 in, and These are the coupling coefficients of the phase coupling model for channels i and j, respectively.

[0012] The cognitive function assessment system, wherein the coupling strength calculation module calculates the coupling strength value of cerebral blood oxygenation and blood pressure in the following manner: Based on the changes in cerebral oxygenated hemoglobin concentration and arterial blood pressure in the dominant prefrontal cortex during a 10-minute data collection period in the subject's resting state, the coupling strength of blood pressure in the 0.6-2Hz frequency band and cerebral oxygenation in the dominant prefrontal cortex in the 0.02-0.07Hz frequency band is calculated. Specifically, the arterial blood pressure signal and the cerebral blood oxygenation signal in the dominant prefrontal cortex are labeled as x and y, respectively. First, the phase information of the blood pressure signal in the 0.6-2Hz frequency band and the cerebral oxygenated hemoglobin concentration change signal in the 0.02-0.07Hz frequency band are extracted through wavelet transformation. Based on this, a coupled phase oscillation model is constructed. A likelihood function is constructed based on Bayesian inference. The coupling coefficient of the phase coupling model is inferred by calculating the stable point of the negative log-likelihood function through recursive operation. Then, the coupling strength from the x to the y channel is calculated. for: , K =2 in, and These are the coupling coefficients of the phase coupling model for the x and y channels, respectively.

[0013] The cognitive function assessment system, wherein the assessment result calculation module assesses cognitive function using the average brain oxygen saturation as follows: when the average brain oxygen saturation of the dominant prefrontal lobe is >60%, it is judged as normal cognition; when 56% ≤ the average brain oxygen saturation of the dominant prefrontal lobe is ≤60%, it is judged as possibly mild cognitive impairment; when the average brain oxygen saturation of the dominant prefrontal lobe is <56%, it is judged as possibly severe cognitive impairment. The assessment result calculation module evaluates cognitive function by measuring the blood oxygen coupling intensity values ​​of the left and right prefrontal lobes. The process is as follows: the blood oxygen coupling intensity values ​​of the left and right prefrontal lobes are tested and recorded monthly. If the blood oxygen coupling intensity values ​​of the left and right prefrontal lobes decrease by more than 20% in three consecutive tests, it is judged that cognitive impairment may occur. Alternatively, if the coupling intensity value of the most recent test is more than 50% lower than the test result 6 months ago, it is tested once a week for three consecutive weeks. If the three test results are all more than 50% lower than the test result 6 months ago, it is judged that cognitive impairment may occur. The assessment result calculation module evaluates cognitive function by measuring the coupling strength between cerebral oxygenation and blood pressure. The process is as follows: the coupling strength between cerebral oxygenation and blood pressure is tested and recorded monthly. If the coupling strength between cerebral oxygenation and blood pressure increases by more than 15% in three consecutive tests, it is judged that cognitive impairment may occur. Alternatively, if the coupling strength value of the most recent test increases by more than 30% compared to the test result 6 months ago, it is tested once a week for three consecutive weeks. If the three test results all increase by more than 30% compared to the test result 6 months ago, it is judged that cognitive impairment may occur.

[0014] The cognitive function assessment system, wherein: The acquisition module is also used to detect blood flow in the middle cerebral artery of the subject at rest using transcranial Doppler ultrasound through the temporal windows on both sides of the head, with a detection depth of 50-60mm; and to obtain the blood flow velocity of the middle cerebral arteries on both sides. The calculation module is also used to calculate the mean pulsatility index (PI) values ​​of both middle cerebral arteries, and the calculation method is as follows:

[0015] Where: V SL V SR V represents the peak systolic velocity of blood flow in the left and right middle arteries, respectively. DL V DR V represents the end-diastolic blood flow velocity in the left and right middle diastolic arteries, respectively. L V R These represent the average flow velocities of blood flow in the left and right middle arteries, respectively. The assessment result calculation module is also used to assess the cognitive function of the subjects based on the mean of the calculated PI value: when the mean PI value is <1, it is judged as normal cognition; when 1≤mean PI value≤1.2, it is judged as possibly mild cognitive impairment; when the mean PI value is >1.2, it is judged as possibly severe cognitive impairment.

[0016] The cognitive function assessment system, wherein: The calculation module also includes a frequency domain correlation value for calculating the blood flow velocity in the dominant middle cerebral artery and the blood oxygen saturation signal. The calculation method is as follows: assuming the blood flow velocity and blood oxygen saturation signal of the dominant middle cerebral artery are respectively... , Its power spectral density function was obtained through Fourier transform, and its power spectrum in the 0.02-0.07Hz frequency band was extracted. and They are respectively and The self-power spectrum, for and Given the cross-power spectrum, the frequency domain correlation value between the two signals is:

[0017] The evaluation result calculation module makes judgments in the following manner: when A value ≥0.4 indicates normal cognitive function; when... A value <0.4 indicates a possible cognitive impairment.

[0018] The cognitive function assessment system as described, wherein: assuming that the result of cognitive function assessment by the mean value of blood oxygen saturation is A, A=0 when the result is normal cognition, A=1 when the result is mild cognitive impairment, and A=2 when the result is severe cognitive impairment; assuming that the result of cognitive function assessment by the cerebral blood oxygen coupling strength values of the left and right prefrontal lobes is B, B=0 when the result is normal cognition, and B=1 when the result indicates possible cognitive impairment; assuming that the result of cognitive function assessment by blood pressure and cerebral blood oxygen coupling strength values is C, C=0 when the result is normal cognition, and C=1 when the result indicates possible cognitive impairment; assuming that the result of cognitive function assessment by the mean pulsatility index PI of the middle cerebral artery is D, D=0 when the result is normal cognition, D=1 when the result is mild cognitive impairment, and D=2 when the result is severe cognitive impairment; assuming that the result of cognitive function assessment by the frequency domain correlation value between the middle cerebral artery blood flow velocity and the blood oxygen saturation signal is E, E=0 when the result is normal cognition, and E=1 when the result indicates cognitive impairment; A comprehensive evaluation system model is established based on the above parameters, and the multiple linear regression analysis method is used to determine the weights W1, W2, W3, W4, W5 of each parameter in the evaluation system, so as to obtain the calculation formula of the comprehensive assessment result P as follows: P=W1 A+W2 B+W3 C+W4 D+W5 E Wherein W1, W2, W3, W4, and W5 are all values between 0 and 1, W1 and W4 are both greater than 0.5, and W2, W3, and W5 are all less than 0.5.

[0019] P is compared with thresholds P1 and P2, and the comprehensive assessment result is determined to be normal cognition, mild cognitive impairment, or severe cognitive impairment.

[0020] The cognitive function assessment system as described, wherein: P=0.9 (A+D)+0.33 B+0.36 C+0.32 E When P ≤ 1, the final result is judged as normal cognition; when 1 < P ≤ 2, the final result is judged as mild cognitive impairment; when P > 2, the final result is judged as severe cognitive impairment.

[0021] A cognitive function assessment method includes: Step 1. Simultaneously collecting cerebral oxygenation data and continuous arterial blood pressure data from both sides of the prefrontal cortex; Step 2. Calculating the average cerebral oxygen saturation, the coupling strength of cerebral oxygenation in both sides of the prefrontal cortex, and the coupling strength of cerebral oxygenation and blood pressure during the collection period; Step 3. Assessing the subject's cognitive function based on the average cerebral oxygen saturation, the coupling strength of cerebral oxygenation in both sides of the prefrontal cortex, and the coupling strength of cerebral oxygenation and blood pressure calculated in Step 2.

[0022] The cognitive function assessment method mentioned above includes the following: during the simultaneous measurement of the subject's continuous arterial blood pressure and cerebral blood oxygenation in the left and right prefrontal lobes, the subject's measurement state is sitting or resting, the continuous measurement time is not less than 10 minutes, and the sampling frequency is not less than 10Hz.

[0023] The cognitive function assessment method described herein, wherein the average value of cerebral blood oxygen saturation in step 2 is calculated as follows: the average value of cerebral blood oxygen saturation in the prefrontal lobe of the dominant side of the brain is calculated during a 3-minute data collection period in the resting state of the subject.

[0024] The cognitive function assessment method described above, wherein the average value of cerebral oxygen saturation in step 2 is calculated as follows: ,

[0025] Among them, R mean R represents the average cerebral oxygen saturation, N is the number of sampling points within the measurement time period, f is the sampling rate, and R0 is the average value. i Let be the blood oxygen saturation value at the i-th sampling point.

[0026] The cognitive function assessment method, wherein: the calculation method for the brain oxygenation coupling strength values ​​of the left and right prefrontal lobes in step 2 is as follows: based on the brain oxygenation hemoglobin concentration change data of the left and right prefrontal lobes during a 10-minute data collection period in the resting state, the effect connectivity strength of the left and right prefrontal lobes in the 0.05–0.15 Hz frequency band is calculated. Specifically, the brain oxygenation signals of the two channels of the left and right prefrontal lobes are labeled as i and j, respectively. First, the phase information of the brain oxygenation hemoglobin concentration change signal in the 0.05–0.15 Hz frequency band is extracted by wavelet transformation. Based on this, a coupled phase oscillation model of the brain oxygenation hemoglobin concentration change signals of the two channels is constructed. Based on Bayesian inference, a likelihood function is constructed. The coupling coefficient of the two-channel phase coupling model is inferred by calculating the stable point of the negative log-likelihood function through recursive operation. Then, the coupling strength from channel i to j is calculated. for: , K =2 in, and These are the coupling coefficients of the phase coupling model for channels i and j, respectively.

[0027] The cognitive function assessment method, wherein: the calculation method for the coupling strength value of cerebral blood oxygenation and blood pressure in step 2 is as follows: based on the changes in cerebral oxygenated hemoglobin concentration and arterial blood pressure in the dominant prefrontal cortex during a 10-minute data collection period in the subject's resting state, the coupling strength of blood pressure in the 0.6-2Hz frequency band and cerebral oxygenation in the dominant prefrontal cortex in the 0.02-0.07Hz frequency band is calculated. Specifically, the arterial blood pressure signal and the cerebral blood oxygenation signal in the dominant prefrontal cortex are labeled as x and y, respectively. First, the phase information of the blood pressure signal in the 0.6-2Hz frequency band and the cerebral oxygenated hemoglobin concentration change signal in the 0.02-0.07Hz frequency band are extracted by wavelet transformation. Based on this, a coupled phase oscillation model is constructed. A likelihood function is constructed based on Bayesian inference. The coupling coefficient of the phase coupling model is inferred by calculating the stable point of the negative log-likelihood function through recursive operation. Then, the coupling strength from the x to the y channel is calculated. for: , K =2 in, and These are the coupling coefficients of the phase coupling model for the x and y channels, respectively.

[0028] The cognitive function assessment method, wherein: in step 3: the process of assessing cognitive function by the average brain oxygen saturation is as follows: when the average brain oxygen saturation of the dominant prefrontal lobe is >60%, it is judged as normal cognition; when 56% ≤ the average brain oxygen saturation of the dominant prefrontal lobe is ≤60%, it is judged as possibly mild cognitive impairment; when the average brain oxygen saturation of the dominant prefrontal lobe is <56%, it is judged as possibly severe cognitive impairment; The process of assessing cognitive function using the blood oxygen coupling intensity values ​​of the left and right prefrontal lobes is as follows: The blood oxygen coupling intensity values ​​of the left and right prefrontal lobes are tested and recorded regularly every month. If the blood oxygen coupling intensity values ​​of the left and right prefrontal lobes decrease by more than 20% in three consecutive tests, it is judged that cognitive impairment may occur. Alternatively, if the coupling intensity value of the most recent test is more than 50% lower than the test result 6 months ago, it is tested once a week for three consecutive weeks. If the three test results are all more than 50% lower than the test result 6 months ago, it is judged that cognitive impairment may occur. The process of assessing cognitive function by measuring the coupling strength between cerebral oxygenation and blood pressure is as follows: The coupling strength between cerebral oxygenation and blood pressure is tested and recorded regularly each month. If the coupling strength between cerebral oxygenation and blood pressure increases by more than 15% in three consecutive tests, it is judged that cognitive impairment may occur. Alternatively, if the coupling strength value of the most recent test increases by more than 30% compared to the test result 6 months ago, it is tested once a week for three consecutive weeks. If the three test results all increase by more than 30% compared to the test result 6 months ago, it is judged that cognitive impairment may occur.

[0029] The cognitive function assessment method described herein, wherein: Step 1 also includes using transcranial Doppler ultrasound to detect blood flow in the middle cerebral arteries of the subject at rest through the temporal windows on both sides of the head, with a detection depth of 50-60 mm; and obtaining the blood flow velocity of the middle cerebral arteries on both sides. Step 2 also includes: calculating the mean pulsatility index (PI) values ​​of both middle cerebral arteries, using the following method:

[0030] Where: V SL V SR V represents the peak systolic velocity of blood flow in the left and right middle arteries, respectively. DL V DR V represents the end-diastolic blood flow velocity in the left and right middle diastolic arteries, respectively. L V R These represent the average flow velocities of blood flow in the left and right middle arteries, respectively. Step 3 also includes: assessing the subject's cognitive function based on the mean PI value calculated in Step 2: when the mean PI value is <1, the subject is judged to have normal cognition; when 1 ≤ mean PI value ≤ 1.2, the subject is judged to possibly have mild cognitive impairment; when the mean PI value is > 1.2, the subject is judged to possibly have severe cognitive impairment.

[0031] The cognitive function assessment method described herein, wherein: Step 2 also includes: calculating the frequency domain correlation value between the blood flow velocity in the dominant middle cerebral artery and the blood oxygen saturation signal. The calculation method is as follows: assuming the blood flow velocity and blood oxygen saturation signal of the dominant middle cerebral artery are respectively... , Its power spectral density function was obtained through Fourier transform, and its power spectrum in the 0.02-0.07Hz frequency band was extracted. and They are respectively and The self-power spectrum, for and Given the cross-power spectrum, the frequency domain correlation value between the two signals is:

[0032] Step 3 further includes: when ≥0.4, it is determined as cognitively normal; when <0.4, it is determined that cognitive impairment may exist.

[0033] The described cognitive function assessment method, wherein: assume that the result of assessing cognitive function through the mean value of blood oxygen saturation is A, where A=0 when the result is cognitively normal, A=1 when the result is mild cognitive impairment, and A=2 when the result is severe cognitive impairment; assume that the result of assessing cognitive function through the left and right prefrontal cerebral blood oxygen coupling intensity values is B, where B=0 when the result is cognitively normal, and B=1 when the result is possible cognitive impairment; assume that the result of assessing cognitive function through blood pressure and cerebral blood oxygen coupling intensity values is C, where C=0 when the result is cognitively normal, and C=1 when the result is possible cognitive impairment; assume that the result of assessing cognitive function through the mean value of the middle cerebral artery pulsatility index PI is D, where D=0 when the result is cognitively normal, D=1 when the result is mild cognitive impairment, and D=2 when the result is severe cognitive impairment; assume that the result of assessing cognitive function through the frequency domain correlation value between the middle cerebral artery blood flow velocity and the blood oxygen saturation signal is E, where E=0 when the result is cognitively normal, and E=1 when the result is cognitive impairment; A comprehensive evaluation system model is established based on the above parameters, and the multiple linear regression analysis method is used to determine the weights W1, W2, W3, W4, W5 of each parameter in the evaluation system, so as to obtain the calculation formula of the comprehensive assessment result P as: P=W1 A+W2 B+W3 C+W4 D+W5 E where W1, W2, W3, W4, and W5 are all values between 0 and 1, W1 and W4 are both greater than 0.5, and W2, W3, and W5 are all less than 0.5.

[0034] P is compared with the thresholds P1 and P2, and the comprehensive assessment result is determined to be cognitively normal, mild cognitive impairment, or severe cognitive impairment.

[0035] The described cognitive function assessment method, wherein: P=0.9 (A+D)+0.33 B+0.36 C+0.32 E When P≤1, the final result is determined as cognitively normal; when 1<P≤2, the final result is determined as mild cognitive impairment; when P>2, the final result is determined as severe cognitive impairment. Brief Description of the Drawings

[0036] Figure 1 A flowchart of cognitive function assessment methods; Figure 2 This is a schematic diagram showing the location for cerebral blood oxygenation sampling. Figure 3 This is a schematic diagram of the structure of a cognitive function assessment system. Detailed Implementation

[0037] The following is in conjunction with the appendix Figure 1-3 The specific embodiments of the present invention will be described in detail below.

[0038] like Figure 1 As shown, a specific embodiment of the present invention provides a cognitive function assessment method, which includes: Step 1. Simultaneously collecting prefrontal cortex cerebral oxygenation data and continuous arterial blood pressure data; Step 2. Calculating the average cerebral oxygen saturation, the coupling strength of cerebral oxygenation in the left and right prefrontal lobes, and the coupling strength between cerebral oxygenation and blood pressure during the collection period; Step 3. Assessing the subject's cognitive function based on the average cerebral oxygen saturation, the coupling strength of cerebral oxygenation in the left and right prefrontal lobes, and the coupling strength between cerebral oxygenation and blood pressure calculated in Step 2. The specific steps are described below: Step 1. Simultaneously measure the subject's continuous arterial blood pressure and cerebral oxygenation data in the left and right prefrontal lobes of the brain, including changes in oxyhemoglobin concentration, deoxyhemoglobin concentration, total hemoglobin concentration, and cerebral oxygen saturation.

[0039] According to a specific embodiment, during the simultaneous measurement of the subject's arterial blood pressure and cerebral oxygenation in both left and right prefrontal lobes, the subject is in a seated, resting position, the continuous measurement time is no less than 10 minutes, and the sampling frequency is no less than 10 Hz. The cerebral oxygenation sampling locations are as follows: Figure 2 As shown. Two brain oxygenation sensors 2A and 2B were fixed to the test sites on the left and right sides of the subject's frontal lobe, respectively. The fixing positions were symmetrical about the left and right sides and aligned with the midline 2C of the subject's face. The center line 2D of the oxygenation sensors was located 1.5cm above the brow bone, avoiding the midline 2C of the face.

[0040] Step 2. Calculate the average cerebral blood oxygen saturation, the coupling strength of cerebral blood oxygen in the left and right prefrontal lobes, and the coupling strength between cerebral blood oxygen and blood pressure during the data collection period.

[0041] According to a specific embodiment, the average value of cerebral blood oxygen saturation is calculated as follows: ,

[0042] Among them, R meanR represents the average cerebral oxygen saturation, N is the number of sampling points within the measurement time period, f is the sampling rate, and R0 is the average value. i Let be the blood oxygen saturation value at the i-th sampling point.

[0043] The calculation method for the coupling strength of blood oxygenation in the left and right prefrontal lobes is as follows: Based on the changes in cerebral oxygenated hemoglobin concentration in the left and right prefrontal lobes during a 10-minute data collection period in the resting state, the effect connectivity strength in the 0.05–0.15 Hz frequency band of the left and right prefrontal lobes is calculated using the Bayesian inference (DBI) method. Specifically, the blood oxygenation signals of the two channels in the left and right prefrontal lobes are labeled as i and j, respectively. First, the phase information of the cerebral oxygenated hemoglobin concentration change signal in the 0.05–0.15 Hz frequency band is extracted by wavelet transformation. Based on this, a coupled phase oscillation model of the cerebral oxygenated hemoglobin concentration change signal of the two channels is constructed. Based on DBI, a likelihood function is constructed. The coupling coefficient of the two-channel phase coupling model is inferred by recursively calculating the stable point of the negative log-likelihood function. The coupling strength from channel i to j is then calculated. for: , K =2 in, and The coupled phase oscillation models for channels i and j are respectively. and These are the coupling coefficients of the phase coupling model for channels i and j, respectively.

[0044] The method for calculating the coupling strength between cerebral oxygenation and blood pressure is as follows: Based on the changes in cerebral oxygenated hemoglobin concentration and arterial blood pressure in the dominant prefrontal cortex during a 10-minute data collection period in a resting state, Bayesian inference was used to calculate the coupling strength between blood pressure in the 0.6-2 Hz frequency band and cerebral oxygenation in the dominant prefrontal cortex in the 0.02-0.07 Hz frequency band. Specifically, the arterial blood pressure signal and the cerebral oxygenation signal in the dominant prefrontal cortex were labeled as x and y, respectively. First, wavelet transform was used to extract the phase information of the blood pressure signal in the 0.6-2 Hz frequency band and the cerebral oxygenated hemoglobin concentration change signal in the 0.02-0.07 Hz frequency band. Based on this, a coupled phase oscillation model was constructed. A likelihood function was constructed based on DBI, and the coupling coefficient of the phase coupling model was inferred by recursively calculating the stationary point of the negative log-likelihood function. The coupling strength from the x to the y channel was then calculated. for: , K =2 in, and The coupled phase oscillation models for the x and y channels are respectively. and These are the coupling coefficients of the phase coupling model for the x and y channels, respectively.

[0045] In the above calculation method, the dominant side is defined as follows: if the subject is right-handed, the left side of the brain is the dominant side; if the subject is left-handed, the right side of the brain is the dominant side. If the subject has unilateral brain damage or developmental disorders, the undamaged side of the brain is the dominant side.

[0046] In addition to the above embodiments, the present invention can also use Granger causality analysis or transfer function analysis to calculate the cerebral blood oxygen coupling strength of the left and right prefrontal lobes and the coupling strength between cerebral blood oxygen and blood pressure.

[0047] Step 3. Assess the subject's cognitive function based on the average cerebral oxygen saturation, the coupling strength of cerebral oxygen in the left and right prefrontal lobes, and the coupling strength between cerebral oxygen and blood pressure calculated in Step 2.

[0048] Specifically, the process of assessing cognitive function by the average brain oxygen saturation is as follows: when the average brain oxygen saturation of the dominant prefrontal lobe is >60%, it is judged as normal cognition; when 56% ≤ the average brain oxygen saturation of the dominant prefrontal lobe is ≤60%, it is judged as possibly mild cognitive impairment; when the average brain oxygen saturation of the dominant prefrontal lobe is <56%, it is judged as possibly severe cognitive impairment.

[0049] The process of assessing cognitive function by measuring the oxygenation coupling intensity of the left and right prefrontal lobes is as follows: The oxygenation coupling intensity values ​​of the left and right prefrontal lobes are tested and recorded regularly every month. If the oxygenation coupling intensity values ​​of the left and right prefrontal lobes decrease by more than 20% in three consecutive tests, it is judged that cognitive impairment may occur. Alternatively, if the coupling intensity value of the most recent test is more than 50% lower than the test result 6 months ago, it is tested once a week for three consecutive weeks. If the three test results are all more than 50% lower than the test result 6 months ago, it is judged that cognitive impairment may occur.

[0050] The process of assessing cognitive function by measuring the coupling strength between cerebral oxygenation and blood pressure is as follows: The coupling strength values ​​of cerebral oxygenation and blood pressure are tested and recorded regularly each month. If the coupling strength values ​​of cerebral oxygenation and blood pressure increase by more than 15% in three consecutive tests, it is judged that cognitive impairment may occur. Alternatively, if the coupling strength value of the most recent test increases by more than 30% compared to the test result 6 months ago, it is tested once a week for three consecutive weeks. If the results of the three tests all increase by more than 30% compared to the test result 6 months ago, it is judged that cognitive impairment may occur.

[0051] According to a specific embodiment, any one of the above three methods may be used for cognitive function assessment, or the cognitive function may be comprehensively judged based on the assessment results of the three methods. Specifically, the method for comprehensively judging using the results of the three methods is as follows: assume that the result of cognitive function assessment through the mean value of blood oxygen saturation is A, where A=0 when the result is normal cognition, A=1 when the result is mild cognitive impairment, and A=2 when the result is severe cognitive impairment; assume that the result of cognitive function assessment through the bilateral prefrontal cerebral oxygen coupling strength is B, where B=0 when the result is normal cognition, and B=1 when the result is possible cognitive impairment; assume that the result of cognitive function assessment through blood pressure and cerebral oxygen coupling strength is C, where C=0 when the result is normal cognition, and C=1 when the result is possible cognitive impairment. The calculation method of the comprehensive assessment result P is: P=A+0.5 B+0.8 C When P≤1, the final result is judged as normal cognition; when 1<P<2.5, the final result is judged as mild cognitive impairment; when P≥2.5, the final result is judged as severe cognitive impairment.

[0052] According to another specific embodiment, the method for comprehensively judging cognitive function using the assessment results of the above three methods is: if the assessment results of more than two methods are consistent, the consistent result is taken as the final assessment result. According to a specific embodiment, if the assessment results based on the bilateral prefrontal cerebral oxygen coupling strength and the coupling strength between cerebral oxygen and blood pressure both indicate the presence of cognitive impairment, the degree of cognitive impairment is judged in combination with the assessment result of cerebral blood oxygen saturation; if the assessment result of cerebral blood oxygen saturation is severe cognitive impairment, it is judged as severe cognitive impairment, otherwise it is judged as mild cognitive impairment. If the assessment result of cerebral blood oxygen saturation is mild or severe cognitive impairment, and the result of any one of the other two methods indicates the presence of cognitive impairment, the assessment result of cerebral blood oxygen saturation is taken as the final assessment result. If the assessment result of cerebral blood oxygen saturation is mild or severe cognitive impairment, and the assessment results of the other two methods both indicate no cognitive impairment, the subject is not temporarily determined to have cognitive impairment, but is considered to have a relatively high risk of cognitive impairment, and continuous monitoring of result changes is required.

[0053] The present invention further provides another embodiment, which further performs cognitive function assessment based on the result of middle cerebral artery blood flow monitoring, specifically: using transcranial Doppler ultrasound to detect the middle cerebral artery blood flow of the subject in a resting state through the temporal windows on both sides of the head, with a detection depth of 50-60mm; acquiring the blood flow velocities of the bilateral middle cerebral arteries.

[0054] Calculate the mean value PI of the pulsatility index PI values of the bilateral middle cerebral artery blood flows mean , the calculation method is:

[0055] Where: V SL V SR V represents the peak systolic velocity of blood flow in the left and right middle arteries, respectively. DL V DR V represents the end-diastolic blood flow velocity in the left and right middle diastolic arteries, respectively. L V R These represent the average flow velocities of blood flow in the left and right middle arteries, respectively.

[0056] When the mean PI value is <1, the cognitive function is considered normal; when 1 ≤ mean PI value ≤ 1.2, the cognitive function may be mild; when the mean PI value is > 1.2, the cognitive function may be severe.

[0057] Calculate the frequency domain correlation between blood flow velocity in the dominant middle cerebral artery and blood oxygen saturation signal. The calculation method is as follows: assuming the blood flow velocity and blood oxygen saturation signal of the dominant middle cerebral artery are respectively... , Its power spectral density function was obtained through Fourier transform, and its power spectrum in the 0.02-0.07Hz frequency band was extracted. and They are respectively and The self-power spectrum, for and Given the cross-power spectrum, the frequency domain correlation value between the two signals is:

[0058] when A value ≥0.4 indicates normal cognitive function; when... A value <0.4 indicates a possible cognitive impairment.

[0059] Cognitive function assessment can be performed solely according to the present method, or the results of the present assessment method can be integrated with the results of assessment using blood pressure and cerebral blood oxygen to perform cognitive function assessment. The specific integration method is as follows: assume that the result of cognitive function assessment by the mean value of blood oxygen saturation is A, where A=0 when the result is normal cognition, A=1 when the result is mild cognitive impairment, and A=2 when the result is severe cognitive impairment; assume that the result of cognitive function assessment by the cerebral blood oxygen coupling intensity of the left and right prefrontal lobes is B, where B=0 when the result is normal cognition, and B=1 when the result is possible cognitive impairment; assume that the result of cognitive function assessment by blood pressure and cerebral blood oxygen coupling intensity is C, where C=0 when the result is normal cognition, and C=1 when the result is possible cognitive impairment; assume that the result of cognitive function assessment by the mean value of the pulsatility index PI of the middle cerebral artery is D, where D=0 when the result is normal cognition, D=1 when the result is mild cognitive impairment, and D=2 when the result is severe cognitive impairment; assume that the result of cognitive function assessment by the frequency domain correlation value between the blood flow velocity of the dominant middle cerebral artery and the blood oxygen saturation signal is E, where E=0 when the result is normal cognition, and E=1 when the result is cognitive impairment. A comprehensive evaluation system model is established based on the above parameters, and the multiple linear regression analysis method is used to determine the weights W1, W2, W3, W4, and W5 of each parameter in the evaluation system, so as to obtain the calculation formula for the comprehensive assessment result P as: P=W1 A+W2 B+W3 C+W4 D+W5 E where W1, W2, W3, W4, and W5 are all values between 0 and 1, W1 and W4 are both greater than 0.5, and W2, W3, and W5 are all less than 0.5.

[0060] P is compared with thresholds P1 and P2, and the comprehensive assessment result is determined to be normal cognition, mild cognitive impairment, or severe cognitive impairment.

[0061] According to a specific embodiment: P=0.9 (A+D)+0.33 B+0.36 C+0.32 E When P ≤ 1, the final result is determined as normal cognition; when 1 < P ≤ 2, the final result is determined as mild cognitive impairment; when P > 2, the final result is determined as severe cognitive impairment.

[0062] Adding parameters related to middle cerebral artery blood flow provides a more comprehensive and accurate reflection of the subject's cognitive function. Validation showed that the comprehensive assessment using five parameters—mean cerebral oxygen saturation, bilateral oxygen coupling strength, oxygen-blood pressure coupling strength, middle cerebral artery pulsatility index, and the frequency domain coherence of blood flow velocity and oxygen saturation—significantly increased accuracy compared to assessments using only three parameters: mean cerebral oxygen saturation, bilateral oxygen coupling strength, and oxygen-blood pressure coupling strength.

[0063] like Figure 3 As shown, the present invention provides a cognitive function assessment system, including: an arterial blood pressure acquisition module 3A, a cerebral blood oxygen acquisition module 3B, a blood pressure-cerebral oxygen synchronization triggering module 3C, a cerebral arterial blood flow detection module 3D, an assessment calculation module 3E, and a result reporting module 3F.

[0064] According to one specific embodiment, the arterial blood pressure acquisition module 3A is a device for continuously measuring human arterial blood pressure data using photoplethysmography (PPG). It includes an infrared light source 3A1, a light signal detection probe 3A2, a probe holder 3A3, and a data processing and transmission module 3A4. The probe holder 3A3 is used to fix the blood pressure detection components (infrared light source 3A1 and light signal detection probe 3A2) to the body part to be measured, which can be the fingertip or the inside of the wrist. The data processing and transmission module 3A4 calculates the blood pressure data based on the signal detected by the light signal detection probe 3A2 and transmits it to the system's evaluation and calculation module 3E.

[0065] The cerebral blood oxygen acquisition module 3B utilizes near-infrared spectroscopy to acquire data on changes in hemoglobin concentration in the cerebral cortex. It includes at least two acquisition sensors 3B1, an optical fiber 3B2, and a data processing and transmission module 3B3. Each sensor 3B1 consists of a near-infrared light source 3B11 and two probes 3B12 and 3B13, with distances of 2 cm and 3 cm between the light source 3B11 and the probes 3B12 and 3B13, respectively. Each sensor 3B1 is connected to the data processing and transmission module 3B3 via the optical fiber 3B2. The data processing and transmission module 3B3 calculates the hemoglobin concentration change data and transmits it to the system's evaluation and calculation module 3E.

[0066] Arterial blood pressure acquisition module 3A and cerebral blood oxygen acquisition module 3B are simultaneously connected to blood pressure-cerebral oxygen synchronization trigger module 3C. Blood pressure-cerebral oxygen synchronization trigger module 3C sends a start acquisition command to arterial blood pressure acquisition module 3A and cerebral blood oxygen acquisition module 3B simultaneously, realizing the synchronous acquisition of blood pressure data and cerebral blood oxygen data.

[0067] The cerebral artery blood flow detection module 3D includes an ultrasound probe 3D1 and a data processing and transmission module 3D2, which are used to detect cerebral artery blood flow-related parameters and transmit them to the system's evaluation and calculation module 3E.

[0068] The assessment calculation module 3E includes a data preprocessing module 3E1, a blood oxygen saturation calculation module 3E2, a coupling strength calculation module 3E3, a blood flow parameter calculation module 3E4, and an assessment result calculation module 3E5. Specifically, the data preprocessing module 3E1 preprocesses the acquired brain hemoglobin concentration signal; the blood oxygen saturation calculation module 3E2 calculates the average blood oxygen saturation during the acquisition period; the coupling strength calculation module 3E3 calculates the blood oxygen coupling strength in the left and right prefrontal lobes and the coupling strength between cerebral blood oxygen and blood pressure; the blood flow parameter calculation module 3E4 calculates the average pulsatility coefficient of both middle cerebral arteries and the frequency domain coherence value of the middle cerebral artery blood flow velocity with prefrontal lobe blood oxygen saturation; and the assessment result calculation module 3E5 calculates the final cognitive function assessment result based on the calculated blood oxygen saturation, the blood oxygen coupling strength in the left and right prefrontal lobes, the coupling strength value between cerebral blood oxygen and blood pressure, the average pulsatility coefficient of both middle cerebral arteries, and the frequency domain coherence value of the middle cerebral artery blood flow velocity with prefrontal lobe blood oxygen saturation. The preprocessing module 3D1 includes a preprocessing model for hemoglobin concentration change signals. The model processing includes: 1) removing noise channels from the acquired raw light intensity data. The criteria for removing channels are that the light intensity data is greater than 1000 or less than 0.5, or the mean / standard deviation is less than 2; 2) converting the light intensity data into a light density time series, using a fourth-order 0.01-0.2 Hz bandpass filter to filter out heartbeat, respiratory components, and low-frequency system noise, and removing motion artifacts; 3) converting the light density data into Δ[oxy-Hb] data, using principal component analysis to remove systemic physiological signals from the Δ[oxy-Hb] time series, and retaining the neurally induced hemodynamic response.

[0069] The Results Reporting Module 3F is used to provide assessment results and generate a report. The assessment report includes: the subject's name, gender, age, test time, the curve showing the change in the dominant prefrontal cortex's blood oxygen saturation value during the test period, the mean value of the dominant prefrontal cortex's blood oxygen saturation in this test, the historical test record curves of the effect connectivity strength between the left and right prefrontal lobes, the historical test record curves of the blood pressure-brain oxygen coupling strength, the average pulsatility coefficient of both middle cerebral arteries in this test, the frequency domain coherence value of the blood flow velocity of the dominant middle cerebral artery and the prefrontal cortex's blood oxygen saturation, and the final results of the cognitive function assessment.

[0070] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0071] This invention enables cognitive function assessment through the detection of physiological information such as blood pressure, cerebral oxygenation, and cerebral blood flow. The assessment method is simple and easy to operate, and the results are objective and quantifiable. It does not rely on professional personnel and can serve as an effective means for large-scale screening of cognitive impairment in communities and elderly care institutions. It is of great significance for the early detection and early intervention of cognitive impairment.

Claims

1. A cognitive function assessment system based on blood pressure and cerebral oxygenation monitoring, comprising a data acquisition module, a calculation module, and an assessment result calculation module, characterized in that: The data acquisition module is used to simultaneously acquire cerebral oxygenation data and continuous arterial blood pressure data from both sides of the prefrontal cortex. The calculation module is used to calculate the average cerebral oxygen saturation, the coupling strength of cerebral oxygenation in both sides of the prefrontal cortex, and the coupling strength of cerebral oxygenation and blood pressure during the acquisition period. The assessment result calculation module is used to assess the subject's cognitive function based on the calculated average cerebral oxygen saturation, the coupling strength of cerebral oxygenation in both sides of the prefrontal cortex, and the coupling strength of cerebral oxygenation and blood pressure. The process of assessing cognitive function using the average cerebral oxygen saturation in the assessment result calculation module is as follows: when the average cerebral oxygen saturation of the dominant prefrontal cortex is >60%, it is judged as normal cognition; when 56% ≤ the average cerebral oxygen saturation of the dominant prefrontal cortex is ≤60%, it is judged as possibly mild cognitive impairment; when the average cerebral oxygen saturation of the dominant prefrontal cortex is <56%, it is judged as possibly severe cognitive impairment. The cognitive function assessment system, wherein the calculation module calculates the average cerebral oxygen saturation in the following manner: ， Among them, R mean R represents the average cerebral oxygen saturation, N is the number of sampling points within the measurement time period, f is the sampling rate, and R0 is the average value. i Let i be the blood oxygen saturation value at the i-th sampling point; The cognitive function assessment system, wherein the calculation module calculates the brain oxygenation coupling strength values ​​of the left and right prefrontal lobes as follows: Based on the changes in cerebral oxygenated hemoglobin concentration in the left and right prefrontal lobes during a 10-minute data collection period in a resting state, the effect connectivity strength of the left and right prefrontal lobes in the 0.05–0.15 Hz frequency band is calculated. Specifically, the brain oxygenation signals of the two channels in the left and right prefrontal lobes are labeled as i and j, respectively. First, the phase information of the cerebral oxygenated hemoglobin concentration change signal in the 0.05–0.15 Hz frequency band is extracted through wavelet transformation. Based on this, a coupled phase oscillation model of the cerebral oxygenated hemoglobin concentration change signal of the two channels is constructed. A likelihood function is constructed based on Bayesian inference. The coupling coefficient of the two-channel phase coupling model is inferred by calculating the stable point of the negative log-likelihood function through recursive operation. Then, the coupling strength from channel i to j is calculated. for: ， K =2 in, and These are the coupling coefficients of the phase coupling model for channels i and j, respectively; The cognitive function assessment system, wherein the calculation module calculates the coupling strength between cerebral oxygenation and blood pressure in the following manner: Based on the changes in cerebral oxygenated hemoglobin concentration and arterial blood pressure in the dominant prefrontal cortex during a 10-minute data collection period in the subject's resting state, the coupling strength between blood pressure in the 0.6-2 Hz frequency band and cerebral oxygenation in the dominant prefrontal cortex in the 0.02-0.07 Hz frequency band is calculated. Specifically, the arterial blood pressure signal and the cerebral oxygenation signal in the dominant prefrontal cortex are labeled as x and y, respectively. First, the phase information of the blood pressure signal in the 0.6-2 Hz frequency band and the cerebral oxygenated hemoglobin concentration change signal in the 0.02-0.07 Hz frequency band are extracted through wavelet transformation. Based on this, a coupled phase oscillation model is constructed. A likelihood function is constructed based on Bayesian inference. The coupling coefficient of the phase coupling model is inferred by calculating the stable point of the negative log-likelihood function through recursive operation. Then, the coupling strength from the x to the y channel is calculated. for: ， K =2 in, and These are the coupling coefficients of the phase coupling model for the x and y channels, respectively.

2. The cognitive function assessment system based on blood pressure and cerebral oxygenation monitoring according to claim 1, characterized in that: The data acquisition modules include: an arterial blood pressure acquisition module and a cerebral blood oxygen acquisition module.

3. The cognitive function assessment system based on blood pressure and cerebral oxygenation monitoring according to claim 1, characterized in that: The acquisition module is also used to detect blood flow in the middle cerebral arteries of the subject at rest using transcranial Doppler ultrasound through the temporal windows on both sides of the head, with a detection depth of 50-60mm; and to obtain the blood flow velocity of the middle cerebral arteries on both sides.

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