Cognitive function evaluation device and cognitive function evaluation system

Abstract

This cognitive function evaluation device comprises a brain signal detection unit, a response motion detection unit, and a computation unit. The brain signal detection unit detects a brain signal, generated for a stimulus, of a subject. A response motion detection unit detects a response motion, generated for the stimulus, of the subject and outputs a response signal. The computation unit detects, from the brain signal, an event-related potential and a motion preparation potential, calculates a response speed from the response signal, and evaluates a cognitive function on the basis of the event-related potential, the motion preparation potential, and the response signal.

Description

Cognitive function assessment device, cognitive function assessment system

[0001] The present invention relates to a technique for assessing cognitive function.

[0002] In Patent Document 1, dementia is identified using electroencephalogram waveforms in response to visual, auditory, and olfactory stimuli.

[0003] Japanese Patent Application Laid-Open No. 2019-13375

[0004] However, in the configuration disclosed in Patent Document 1, cognitive function is assessed only based on the event-related potential in response to a stimulus, and therefore, in the case of a subject whose other functions are declining, such as an elderly person, the decline in cognitive function cannot be accurately evaluated.

[0005] Therefore, an object of the present invention is to provide a technique for evaluating the cognitive function of a subject with higher accuracy.

[0006] The cognitive function assessment device of the present invention includes a brain signal detection unit, a response movement detection unit, and a calculation unit. The brain signal detection unit detects the brain signals of the subject generated in response to stimuli. The response movement detection unit detects the response movements of the subject generated in response to the stimuli and outputs a response signal. The calculation unit detects event-related potentials and readiness potentials from the brain signals, calculates a response speed from the response signal, and evaluates cognitive function based on the event-related potentials, readiness potentials, and response speed.

[0007] In this configuration, cognitive function is evaluated using the event-related potential to the stimulus, the motor readiness potential to the stimulus, and the response speed. This improves the accuracy of the evaluation of the subject's cognitive function, as the evaluation is performed using the cognitive function to the stimulus, the motor instruction function to the stimulus, and the motor function to the stimulus.

[0008] According to the present invention, the cognitive function of a subject can be evaluated with higher accuracy.

[0009] FIG. 1 is a functional block diagram of a cognitive function assessment system according to a first embodiment of the present invention. FIG. 2 is a functional block diagram showing the configuration of a brain signal detection unit. FIG. 3 is a diagram showing an overview of a state in which detection gear is attached to a cognitive function subject. FIG. 4 is a functional block diagram showing the configuration of a calculation unit. FIGS. 5A and 5B are diagrams showing a concept of cognitive function assessment. FIG. 6 is a flowchart showing an example of a cognitive function assessment method according to the first embodiment. FIG. 7 is a flowchart showing an example of cognitive function assessment. FIG. 8 is a flowchart showing an example of a method for classifying and assessing cognitive function decline. FIG. 9 is a functional block diagram of a cognitive function assessment system according to a second embodiment of the present invention. FIG. 10 is a flowchart showing an example of a cognitive function assessment method according to the second embodiment. FIG. 11 is a functional block diagram of a cognitive function assessment system according to a third embodiment of the present invention. FIG. 12 is a flowchart showing an example of a cognitive function assessment method according to the third embodiment. FIG. 13 is a flowchart showing an example of a cognitive function assessment method according to the fourth embodiment. FIG. 14 is a flowchart showing an example of a cognitive function assessment method according to the fourth embodiment. FIG. 15 is a flowchart showing an example of a cognitive function assessment method according to the fifth embodiment.

[0010] (First embodiment) A cognitive function assessment system according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a functional block diagram of the cognitive function assessment system according to the first embodiment of the present invention. Fig. 2 is a functional block diagram showing the configuration of a brain signal detection unit. Fig. 3 is a diagram showing an overview of the state in which detection gear is attached to a subject of cognitive function. Fig. 4 is a functional block diagram showing the configuration of a calculation unit.

[0011] 1 , the cognitive function assessment system 1 includes a cognitive function assessment device 10 and a stimulus presentation device 20. The cognitive function assessment device 10 includes a brain signal detection unit 11, a response movement detection unit 12, and a calculation unit 13.

[0012] (Stimulus Presentation Device 20) The stimulus presentation device 20 presents a visual stimulus to the subject. For example, the stimulus presentation device 20 is a display device capable of displaying a predetermined image.

[0013] The stimulus presentation device 20 periodically displays a first image and a second image of different shapes (e.g., two types of circles of different sizes) as visual stimuli, with the first image and the second image being displayed at different frequencies.

[0014] For example, the first image is displayed frequently and the second image is displayed infrequently. More specifically, the first image is displayed every second, and the first image is replaced with the second image at a specific timing.

[0015] The stimulus presentation device 20 presents visual stimuli upon receiving, for example, an instruction to start presenting visual stimuli from the calculation unit 13 of the cognitive function assessment device 10. Note that the stimulus presentation device 20 does not necessarily receive the instruction to start presenting visual stimuli from the calculation unit 13. For example, a separate functional unit (not shown) may present visual stimuli in synchronization with each process or each sampling period of the calculation unit 13.

[0016] 2, the brain signal detection unit 11 includes a brain signal sensor 111 and a brain signal processing unit 112. The brain signal sensor 111 is realized by, for example, a sensor capable of acquiring known brain signals.

[0017] Brain signal sensor 111 is attached to the subject using, for example, detection gear 100 as shown in Fig. 3. Detection gear 100 includes headband 101, brain signal sensor 1111, and brain signal sensor 1112. Brain signal sensor 1111 and brain signal sensor 1112 correspond to brain signal sensor 111 in Fig. 2. Note that detection gear 100 may include any number of brain signal sensors.

[0018] The headband 101 is made of a strip-shaped base material. The headband 101 has, for example, elasticity. The headband 101 is worn on the head 800 of the subject 80. The brain signal sensor 1111 is provided on the inside of the headband 101 on the side of the occipital region 801. The brain signal sensor 1112 is provided on the inside of the headband 101 on the side of the forehead 802. The brain signal sensors 1111 and 1112 acquire brain signals from the subject 80 and output them to the brain signal processing unit 112.

[0019] Brain signal processing unit 112 is realized by, for example, an electronic circuit or an IC. Brain signal processing unit 112 performs filtering, amplification, and other processes on the brain signals acquired by brain signal sensor 111 (brain signal sensors 1111 and 1112). Brain signal processing unit 112 outputs the brain signals after predetermined processing to calculation unit 13. Note that detection gear 100 is not limited to that disclosed in FIG. 3 and may be incorporated into, for example, a head-mounted display (HMD) or a VR (Virtual Reality) device.

[0020] (Response movement detection unit 12) The response movement detection unit 12 is realized by, for example, a physical button, a touch panel, an operation input device (e.g., a mouse) equipped on the cognitive function assessment device 10, etc. In other words, the response movement detection unit 12 is realized by a member that can detect the movement made by the subject 80 when an event to be recognized occurs.

[0021] The response movement detection unit 12 detects the input timing (operation timing) of the response movement by the subject 80, and calculates a response signal. The response movement detection unit 12 outputs the response signal to the calculation unit 13.

[0022] 4, the calculation unit 13 includes a sampling period determination unit 131, an event-related potential detection unit 132, a readiness potential detection unit 133, a response speed detection unit 134, and an analysis unit 135. The calculation unit 13 is realized by an electronic circuit, an IC, an MPU, etc.

[0023] The sampling period determination unit 131 receives a stimulus trigger from the stimulus presentation device 20 or a response signal from the response movement detection unit 12. The stimulus trigger is a trigger that indicates the timing at which an image (video) of the response target is presented. The sampling period determination unit 131 determines a sampling period for detecting an event-related potential and a sampling period for detecting a readiness potential.

[0024] The sampling period determination section 131 specifies a sampling period for detecting an event-related potential to the event-related potential detection section 132. The sampling period determination section 131 specifies a sampling period for detecting a readiness potential to the readiness potential detection section 133.

[0025] A brain signal is input to the event-related potential detection unit 132. The event-related potential detection unit 132 detects an event-related potential (e.g., P300) related to the visual stimulus from the waveform of the brain signal during a sampling period for detecting the event-related potential of the visual stimulus. The event-related potential detection unit 132 outputs the detected event-related potential to the analysis unit 135.

[0026] A brain signal is input to the beep potential detection unit 133. The beep potential detection unit 133 detects a beep potential from the waveform of the brain signal during a sampling period for detecting the beep potential. The beep potential detection unit 133 outputs the beep potential to the analysis unit 135.

[0027] A stimulus trigger and a response signal are input to the response speed detection unit 134. The response speed detection unit 134 detects the response speed using the time difference between the timing of the stimulus trigger and the timing of the response signal. The response speed detection unit 134 outputs the response speed to the analysis unit 135. Note that the response speed detection unit 134 may detect the response signal using the time difference between the timing of a readiness potential and the timing of the response signal instead of the stimulus trigger.

[0028] The analysis unit 135 evaluates cognitive function using the event-related potential, the readiness potential, and the response speed. More specifically, the analysis unit 135 evaluates cognitive function using, for example, the following method. Figures 5(A) and 5(B) are diagrams showing the concept of evaluating cognitive function.

[0029] The analysis unit 135 calculates an index INDv related to the recognition of visual stimuli using the event-related potential. The index INDv is calculated using the waveform, amplitude, etc. of the event-related potential. For example, the index INDv is an index indicating that the lower the index value, the lower the cognitive function in response to visual stimuli.

[0030] The analysis unit 135 calculates an index INDm related to motor preparation for a stimulus using the readiness potential. The index INDm is calculated using the waveform, amplitude, occurrence timing, etc. of the readiness potential. For example, the index INDm is an index indicating that the lower the index value, the lower the motor preparation ability for a stimulus.

[0031] The analysis unit 135 calculates an index INDr relating to motor function in response to a stimulus using the response speed. The index INDr is calculated using the response speed. For example, the lower the index value of the index INDr, the lower the motor ability in response to a stimulus.

[0032] The analysis unit 135 evaluates the cognitive function using the index INDv, the index INDm, and the index INDr.

[0033] For example, the analysis unit 135 compares the indices INDv, INDm, and INDr of the subject 80 with the indices of the cognitive assessment criteria. The analysis unit 135 uses the comparison results to evaluate the cognitive function.

[0034] For example, in the case of FIG. 5A , the index INDv of the subject 80 is higher than the index INDv of the cognitive evaluation standard. The index INDm of the subject 80 is similar to the index INDm of the cognitive evaluation standard. The index INDr of the subject 80 is lower than the index INDr of the cognitive evaluation standard. In such cases, the analysis unit 135 evaluates that the cognitive function in response to the stimulus is normal, but the motor system ability in response to the stimulus is low. As a result, for example, the analysis unit 135 evaluates that there is no problem with the cognitive function, but the motor system ability is lower than the average level.

[0035] On the other hand, when the analysis unit 135 detects that the index INDr is lower than the cognitive assessment standard, the analysis unit 135 evaluates that the cognitive function is low. As a result, for example, the analysis unit 135 evaluates that there is a risk of dementia.

[0036] Furthermore, for example, the analysis unit 135 compares each of the current indexes of the subject 80 with each of the past indexes for the index INDv, the index INDm, and the index INDr. The analysis unit 135 uses the comparison results to evaluate the decline in cognitive function. That is, the analysis unit 135 evaluates the decline in cognitive function based on changes in the indexes at different times (in other words, changes in cognitive function).

[0037] For example, in the case of FIG. 5B , the subject 80's current index INDv is lower than the previous index INDv. The subject 80's current index INDm is similar to the previous index INDm. The subject 80's current index INDr is lower than the previous index INDr of the cognitive evaluation standard. In such cases, the analysis unit 135 evaluates that the cognitive function and motor ability have declined.

[0038] On the other hand, if the analysis unit 135 detects that the current index INDv is equal to or higher than the previous index INDv, it evaluates that the cognitive function has not declined. If the current index INDm and the current index INDr are lower than these previous indexes, the analysis unit 135 evaluates that the cognitive function has not declined but that the motor ability has declined.

[0039] In this way, the cognitive function assessment system 1 and the cognitive function assessment device 10 can assess cognitive function using multiple indices, including the motor system's response to visual stimuli, allowing the cognitive function assessment system 1 and the cognitive function assessment device 10 to more accurately assess the subject's cognitive function, taking into account the ability of the subject's motor system.

[0040] The cognitive function assessment device 10 may estimate the MMSE score using the combination of the event-related potential, the readiness potential, and the response speed, or the combination of the indexes INDv, INDm, and INDr. For example, the cognitive function assessment device 10 learns the combination of the event-related potential, the readiness potential, and the response speed, or the combination of the indexes INDv, INDm, and INDr, as features, and associates them with the MMSE score. The cognitive function assessment device 10 estimates the MMSE score by substituting the current combination of the event-related potential, the readiness potential, and the response speed, or the combination of the indexes INDv, INDm, and INDr, into the estimation formula obtained by this learning.

[0041] Although not shown in the figures, the cognitive function assessment device 10 is also equipped with a display device, which can display the assessment results.

[0042] (Method for assessing cognitive function) Fig. 6 is a flowchart showing an example of the method for assessing cognitive function according to the first embodiment. Note that, with regard to each process in Fig. 6, the description of the same parts as those in the description of the configuration described above will be omitted.

[0043] The stimulus presentation device 20 presents a visual stimulus (S11). The calculation unit 13 of the cognitive function assessment device 10 detects a visual event-related potential (S12). The calculation unit 13 of the cognitive function assessment device 10 detects a readiness potential (S13). The calculation unit 13 of the cognitive function assessment device 10 detects a response speed (S14).

[0044] The calculation unit 13 of the cognitive function assessment device 10 evaluates cognitive function using the visual event-related potential, the motor readiness potential, and the response speed (S15). Specifically, the calculation unit 13 executes the processes shown in Figs. 7 and 8, for example. Fig. 7 is a flowchart showing an example of cognitive function assessment. Fig. 8 is a flowchart showing an example of a method for classifying and assessing cognitive decline.

[0045] The calculation unit 13 calculates an index INDv related to visual stimulation using the event-related potential (S51). The calculation unit 13 calculates an index INDm related to motor commands using the readiness potential (S52). The calculation unit 13 calculates an index INDr related to motor function using the response speed. Note that the order of calculation of the index INDv, index INDm, and index INDr is not limited to this, and they may be calculated in parallel.

[0046] The calculation unit 13 classifies and evaluates the deteriorated function using the index INDv, the index INDm, and the index INDr (S54). More specifically, the calculation unit 13 performs, for example, the process shown in FIG.

[0047] If the index INDv related to visual stimulation is abnormal (S541: YES), the calculation unit 13 classifies the state as a state of decreased cognitive function or a state of low cognitive function (S542). The index INDv is abnormal when, for example, the index INDv is lower than a reference value indicating low cognitive function.

[0048] If the index INDv is normal (S541: NO), the calculation unit 13 classifies the cognitive function as being in a normal state (S543). A normal index INDv means, for example, that the index INDv is higher than a reference value indicating low cognitive function. Note that, as with the index INDv, a preset reference value is used for specific classification of the following indexes INDm and INDr. Therefore, a description of the classification method using the reference value for the following indexes INDm and INDr will be omitted.

[0049] If the index INDm related to exercise preparation is abnormal (S544: YES), the calculation unit 13 classifies the state as a state in which the exercise instruction function is impaired or the exercise instruction function is low (S545). In other words, the calculation unit 13 classifies the state as a state in which the cognitive function is normal but the exercise instruction function is low.

[0050] If the index INDm is normal (S544: NO), the calculation unit 13 classifies the exercise instruction function as being in a normal state (S546).

[0051] If the motor function index INDr is abnormal (S547: YES), the calculation unit 13 classifies the subject as having a state of decreased motor function or a state of low motor function (S548). That is, the calculation unit 13 classifies the subject as having normal cognitive function and motor control function (i.e., brain function) but low motor function.

[0052] If the motor function index INDr is normal (S547: NO), the calculation unit 13 classifies the motor function as being in a normal state (S549). That is, the calculation unit 13 classifies the cognitive function, motor instruction function, and motor function as being free of problems.

[0053] In this way, the cognitive function assessment device 10 can classify and assess cognitive function by combining indices using event-related potentials with indices related to movement, thereby enabling the cognitive function assessment device 10 to assess cognitive function with greater accuracy.

[0054] Second Embodiment A cognitive function assessment system according to a second embodiment of the present invention will be described with reference to the drawings. While the cognitive function assessment system 1 according to the first embodiment uses visual stimuli, the cognitive function assessment system 1A according to the second embodiment differs in that it uses auditory stimuli. Other basic configurations and processes of the cognitive function assessment system 1A are the same as those of the cognitive function assessment system 1, and descriptions of similar parts will be omitted.

[0055] (Configuration and processing of cognitive function assessment system 1A) Fig. 9 is a functional block diagram of a cognitive function assessment system according to a second embodiment of the present invention. The cognitive function assessment system 1A according to the second embodiment includes a cognitive function assessment device 10A and a stimulus presentation device 20A.

[0056] The stimulus presentation device 20A presents an auditory stimulus. For example, the stimulus presentation device 20A is a speaker or the like that can emit a predetermined sound.

[0057] The stimulus presentation device 20A emits, as auditory stimuli, a first sound and a second sound having different frequencies at a predetermined cycle, where the emission frequency of the first sound is different from the emission frequency of the second sound.

[0058] For example, the first sound is emitted frequently and the second sound is emitted infrequently. More specifically, the first sound is emitted every second in a steady state, and the first sound is replaced with the second sound at a specific timing.

[0059] The stimulus presentation device 20A presents an auditory stimulus upon receiving, for example, an instruction to start presenting an auditory stimulus from the calculation unit 13A of the cognitive function assessment device 10A.

[0060] The calculation unit 13A of the cognitive function assessment device 10A differs from the calculation unit 13 according to the first embodiment in that an event-related potential in response to an auditory stimulus is used as the event-related potential. The other configurations and processes of the calculation unit 13A are the same as those of the calculation unit 13, and descriptions thereof will be omitted except for points requiring additional explanation.

[0061] The event-related potential detection unit 132 (see FIGS. 8 and 4) of the calculation unit 13A detects an event-related potential (e.g., MMN) related to the auditory stimulus from the waveform of the brain signal during a sampling period for detecting the event-related potential of the auditory stimulus. The event-related potential detection unit 132 outputs the detected event-related potential to the analysis unit 135.

[0062] The analysis unit 135 calculates an index INDh related to auditory stimulation using the event-related potential of the auditory stimulation. The analysis unit 135 evaluates cognitive function using the index INDh related to auditory stimulation, the index INDm related to motor instructions, and the index INDr related to motor function.

[0063] (Cognitive Function Assessment Method) FIG. 10 is a flowchart showing an example of a cognitive function assessment method according to the second embodiment.

[0064] The stimulus presentation device 20A presents an auditory stimulus (S21). The calculation unit 13A of the cognitive function assessment device 10A detects an auditory event-related potential (S22). The calculation unit 13A detects a readiness potential (S23). The calculation unit 13A detects a response speed (S24). The calculation unit 13A evaluates cognitive function using the auditory event-related potential (index INDh), the readiness potential (index INDm), and the response speed (index INDr) (S25).

[0065] In this way, the cognitive function assessment system 1A according to the second embodiment assesses cognitive function using auditory stimulation. In this case, the cognitive function assessment system 1A can assess cognitive function with higher accuracy, similar to the cognitive function assessment system 1.

[0066] (Third Embodiment) A cognitive function assessment system according to a third embodiment of the present invention will be described with reference to the drawings. While the cognitive function assessment system 1 according to the first embodiment uses visual stimuli and the cognitive function assessment system 1A according to the second embodiment uses auditory stimuli, the cognitive function assessment system 1B according to the third embodiment differs in that it selectively uses visual and auditory stimuli. The other basic configurations and processes of the cognitive function assessment system 1B are the same as those of the cognitive function assessment systems 1 and 1A, and descriptions of similar parts will be omitted.

[0067] 11 is a functional block diagram of a cognitive function assessment system according to a third embodiment of the present invention. The cognitive function assessment system 1B according to the third embodiment includes a cognitive function assessment device 10B and a stimulus presentation device 20B.

[0068] The stimulus presentation device 20B selectively presents an auditory stimulus and a visual stimulus.

[0069] The calculation unit 13B of the cognitive function assessment device 10B performs a comprehensive assessment using assessment results (assessment results of auditory cognitive function) that include event-related potentials of auditory stimuli (auditory event-related potentials) and assessment results (assessment results of visual cognitive function) that include event-related potentials of visual stimuli (visual event-related potentials).

[0070] For the overall evaluation, for example, the calculation unit 13B compares the evaluation results of the auditory cognitive function and the visual cognitive function, and determines the result of the lower cognitive function as the overall evaluation. Alternatively, the calculation unit 13B may score the evaluation results of the auditory cognitive function and the visual cognitive function, and determine the overall evaluation by averaging these scores. Alternatively, the calculation unit 13B may weight either the evaluation results of the auditory cognitive function or the evaluation results of the visual cognitive function, and assign a higher weight to either evaluation result to determine the overall evaluation.

[0071] In this way, the cognitive function assessment system 1B performs a comprehensive assessment using a plurality of types of assessment results using different event-related potentials, which allows the cognitive function assessment device 10B to assess cognitive function with even greater accuracy.

[0072] (Cognitive Function Assessment Method) FIG. 12 is a flowchart showing an example of a cognitive function assessment method according to the third embodiment.

[0073] The cognitive function assessment device 10B evaluates auditory cognitive function (S20: see FIG. 10). The cognitive function assessment device 10B evaluates visual cognitive function (S10: see FIG. 6). The cognitive function assessment device 10B performs a comprehensive evaluation using the assessment results of auditory cognitive function and visual cognitive function (S30).

[0074] (Fourth embodiment) A cognitive function assessment system according to a fourth embodiment of the present invention will be described with reference to the drawings. The cognitive function assessment system according to the fourth embodiment has a configuration similar to that of the cognitive function assessment system 1B according to the third embodiment, but has a different assessment method. Therefore, the following description will focus on the differences between the cognitive function assessment system according to the fourth embodiment and the cognitive function assessment system according to the third embodiment, and will omit a description of the other differences.

[0075] 13 and 14 are flowcharts showing an example of the cognitive function evaluation method according to the fourth embodiment.

[0076] In the case of Figure 13, the cognitive function assessment system performs a hearing loss assessment test (S41). Specifically, the stimulus presentation device emits a sound for detecting hearing loss. The sound for detecting hearing loss may be the same as or different from the sound for presenting the auditory stimulus. The cognitive function assessment device detects the response of the subject 80 to the sound for detecting hearing loss. This response can be detected using a method similar to that used to detect responses to auditory stimuli.

[0077] When the cognitive function assessment system determines that the subject 80 does not have hearing loss (S42: NO), it evaluates the auditory cognitive function (S20). Specifically, the cognitive function assessment device instructs the stimulus presentation device to present an auditory stimulus, and the stimulus presentation device presents the auditory stimulus. The cognitive function assessment device evaluates the cognitive function using the auditory stimulus.

[0078] When the cognitive function assessment system determines that the subject 80 has hearing loss (S42: YES), it evaluates the visual cognitive function (S10). Specifically, the cognitive function assessment device instructs the stimulus presentation device to switch from auditory stimuli to visual stimuli and present the visual stimuli, and the stimulus presentation device presents the visual stimuli. The cognitive function assessment device evaluates the cognitive function using the visual stimuli.

[0079] In addition, determining whether or not a person has hearing loss can be achieved, for example, by repeating the emission of a sound for detecting hearing loss and the detection of sound recognition or response input using brain signals a predetermined number of times, and detecting that the sound cannot be recognized a predetermined number of times, or that the response input cannot be detected a predetermined number of times.

[0080] In the case of Fig. 14, the cognitive function assessment system performs the process up to the determination of hearing loss, and in the case of hearing loss, the process is the same as in Fig. 13. In the case of Fig. 14, the cognitive function assessment system performs the following process if the case is not hearing loss.

[0081] The cognitive function assessment system evaluates auditory cognitive function and visual cognitive function (S20, S10). The cognitive function assessment system performs a comprehensive assessment using the evaluation of auditory cognitive function and the evaluation of visual cognitive function (S30).

[0082] In this way, the cognitive function assessment system can evaluate cognitive function with greater accuracy by taking into account the physical condition of the subject.

[0083] Fifth Embodiment A cognitive function assessment system according to a fifth embodiment of the present invention will be described with reference to the drawings. The cognitive function assessment system according to the fifth embodiment differs from the cognitive function assessment system according to the fourth embodiment, which performs the processing shown in FIG. 14 , in that an initial test is added and the results of the initial test are reflected in the overall assessment. The processing of the cognitive function assessment system according to the fifth embodiment is the same as that of the cognitive function assessment system according to the fourth embodiment, and a description of similar parts will be omitted.

[0084] FIG. 15 is a flowchart showing an example of a cognitive function evaluation method according to the fifth embodiment.

[0085] The cognitive function assessment system performs an initial test (S51). The initial test is, for example, at least one of a test to detect the wearing state and a test to measure the concentration level of the subject 80.

[0086] In a test to detect the wearing state of the detection gear 100, the cognitive function assessment system, for example, measures the amplitude of a brain signal to detect the wearing state. For example, if the amplitude is less than a predetermined threshold, it determines that the wearing state is improper, and if the amplitude is equal to or greater than the predetermined threshold, it determines that the wearing state is normal. If the wearing state is improper, the cognitive function assessment system may notify the subject 80, the evaluator, or the like that the wearing state is improper. This can provide support, for example, to correct the wearing state to a normal state.

[0087] In a test to measure concentration, the cognitive function assessment system, for example, performs frequency analysis of brain signals and determines the state of alpha waves. The cognitive function assessment system determines the state of the subject 80, such as whether the subject is unable to concentrate, based on the state of alpha waves (brain signals of a specific frequency). For example, the cognitive function assessment system determines that the subject 80 is normal if the alpha waves are within the normal range, and estimates that the subject 80 is abnormal if the alpha waves are outside the normal range. Abnormal here means, for example, the possibility of a decline in cognitive function.

[0088] If the condition and wearing state of the subject 80 are normal (S52: YES), the cognitive function assessment system proceeds to the hearing loss assessment test (S41).

[0089] If the condition of the subject 80 is abnormal (S52: NO), the cognitive function assessment system reflects this determination result in the overall assessment (S30A). Note that if the condition of the subject 80 is abnormal, the cognitive function assessment system may not evaluate the cognitive function (cannot evaluate).

[0090] In this way, the cognitive function evaluation system can evaluate cognitive function with greater accuracy by taking into account the wearing state of the detection gear 100 and the physical and mental states of the subject.

[0091] <1> A cognitive function assessment device comprising: a brain signal detection unit that detects brain signals of a subject generated in response to a stimulus; a response movement detection unit that detects response movements of the subject generated in response to the stimulus and outputs a response signal; and a calculation unit that detects an event-related potential and a readiness potential from the brain signals, calculates a response speed from the response signal, and evaluates cognitive function based on the event-related potential, the readiness potential, and the response speed.

[0092] <2> The cognitive function assessment device of <1>, wherein the calculation unit calculates a first index related to stimulus recognition using the event-related potential, calculates a second index related to motor commands using the motor readiness potential, and calculates a third index related to motor function using the response speed, and evaluates the cognitive function using the first index, the second index, and the third index.

[0093] <3> The cognitive function assessment device according to <1> or <2>, wherein the calculation unit assesses the cognitive function at a plurality of different times, and assesses a decline in the cognitive function based on a change in the cognitive function at the plurality of times.

[0094] <4> The cognitive function assessment device according to any one of <1> to <3>, wherein the calculation unit estimates an MMSE score using the assessment result of the cognitive function.

[0095] <5> A cognitive function assessment system comprising: the cognitive function assessment device according to any one of <1> to <4>; and a stimulus presentation device that presents the stimulus to the subject.

[0096] <6> The cognitive function assessment system according to <5>, wherein the stimulus presentation device presents a visual stimulus, and the calculation unit detects, as the event-related potential, an event-related potential caused by the visual stimulus.

[0097] <7> The cognitive function assessment system according to <5>, wherein the stimulus presentation device presents an auditory stimulus, and the calculation unit detects, as the event-related potential, an event-related potential caused by the auditory stimulus.

[0098] <8> The cognitive function evaluation system of <5>, wherein the stimulus presentation device selectively presents a visual stimulus and an auditory stimulus, the calculation unit detects at least one of an event-related potential due to the visual stimulus and an event-related potential due to the auditory stimulus as the event-related potential, and the cognitive function is evaluated using the event-related potential due to the visual stimulus or the event-related potential due to the auditory stimulus.

[0099] <9> The cognitive function assessment system of <8>, wherein the stimulus presentation device presents a sound for detecting hearing loss before presenting the auditory stimulus, the calculation unit detects hearing loss using at least the brain signal, and upon detecting the hearing loss, instructs the stimulus presentation device to present the visual stimulus, the stimulus presentation device presents the visual stimulus, and the calculation unit evaluates the cognitive function using an event-related potential due to the visual stimulus.

[0100] <10> The cognitive function assessment system according to any one of <5> to <9>, wherein the calculation unit estimates a possibility of cognitive function decline using a brain signal of a specific frequency in the brain signal before a stimulus is presented, and evaluates the cognitive function using the result of the estimation.

[0101] DESCRIPTION OF SYMBOLS 1, 1A, 1B: Cognitive function assessment system 10, 10A, 10B: Cognitive function assessment device 11: Brain signal detection unit 12: Response movement detection unit 13, 13A, 13B: Calculation unit 20, 20A, 20B: Stimulus presentation device 80: Subject 100: Detection gear 101: Headband 111, 1111, 1112: Brain signal sensor 112: Brain signal processing unit 131: Sampling period determination unit 132: Event-related potential detection unit 133: Behavior readiness potential detection unit 134: Response speed detection unit 135: Analysis unit 800: Head 801: Occipital region 802: Forehead

Claims

1. a brain signal detection unit that detects a brain signal of a subject generated in response to a stimulus; a response movement detection unit that detects a response movement of the subject occurring in response to the stimulus and outputs a response signal; a calculation unit that detects an event-related potential from the brain signal, calculates a response speed from a time from the input of the stimulus to the input of the response signal, and evaluates a cognitive function based on the event-related potential and the response speed; Equipped with The calculation unit is Calculating an index related to stimulus recognition using the event-related potential; Calculating an index related to motor function using the response speed; If the index regarding the stimulus recognition is abnormal, evaluate the decline in cognitive function; If the index regarding the stimulus recognition is normal and the index regarding the motor function is abnormal, the cognitive function is evaluated as being normal but the motor function is evaluated as being in a low state. Cognitive function assessment device.

2. The calculation unit, Further detecting a readiness potential from the brain signal; Calculating an index related to a motor instruction function using the motor preparation potential; If the index regarding the stimulus cognition is normal and the index regarding the motor instruction function is abnormal, the cognitive function is evaluated as being normal but the motor instruction function is low. The cognitive function evaluation device according to claim 1 .

3. The calculation unit is assessing said cognitive function at different times; and evaluating the decline in cognitive function based on changes in the cognitive function at the multiple times. The cognitive function evaluation device according to claim 1 or 2.

4. The calculation unit is The cognitive function assessment results are used to estimate an MMSE score. The cognitive function evaluation device according to claim 1 or 2.

5. The cognitive function evaluation device according to claim 1 or 2, a stimulus presentation device that presents the stimulus to the subject; Equipped with Cognitive function assessment system.

6. The stimulus presentation device presents a visual stimulus; The calculation unit is an event-related potential caused by the visual stimulus is detected as the event-related potential; The cognitive function evaluation system according to claim 5 .

7. The stimulus presentation device presents an auditory stimulus; The calculation unit is As the event-related potential, an event-related potential due to the auditory stimulus is detected. The cognitive function evaluation system according to claim 5 .

8. The stimulus presentation device selectively presents a visual stimulus and an auditory stimulus; The calculation unit is Detecting at least one of an event-related potential due to the visual stimulus and an event-related potential due to the auditory stimulus as the event-related potential; The cognitive function is evaluated using the event-related potential due to the visual stimulus or the event-related potential due to the auditory stimulus. The cognitive function evaluation system according to claim 5 .

9. The stimulus presentation device presents a sound for detecting hearing loss before presenting the auditory stimulus; The calculation unit is Detecting hearing loss using at least the brain signals; When the hearing loss is detected, instructing the stimulus presentation device to present the visual stimulus; The stimulus presentation device presents the visual stimulus; The computing unit evaluates the cognitive function by using an event-related potential due to the visual stimulus. The cognitive function evaluation system according to claim 8 .

10. The calculation unit is estimating a possibility of cognitive decline using a brain signal of a specific frequency in the brain signal before the stimulus is presented; The cognitive function is evaluated using the result of the estimation. The cognitive function evaluation system according to claim 5 .