Olfaction recognition method for early clinical screening of Alzheimer's disease

Abstract

The invention discloses an olfaction recognition method for early clinical screening of Alzheimer's disease. By finding that the olfactory ability of AD mice is poorer than that of normal mice, a theoretical basis is provided for early screening of Alzheimer's disease by early olfactory lesions. The olfaction recognition technology is used for AD early-stage screening, it is found that the olfaction recognition ability is reduced along with reduction of the cognitive ability in middle-aged and elderly people in China, it is indicated that SCD old people converted into AD risks can be recognized, and the function of screening middle-aged and elderly Alzheimer's disease risk patients is achieved. Therefore, the olfaction evaluation technology which has the characteristics of remarkable low cost benefit and complete non-invasive property and is extremely simple to operate is expected to become an extremely reliable tool for preliminary detection of the Alzheimer's disease in the future.

Description

Technical Field

[0001] This invention relates to the field of brain health assessment technology, and in particular to an Alzheimer's disease assessment system and method. Background Technology

[0002] Alzheimer's disease (AD) is a neurodegenerative disease caused by complex changes in the brain resulting from cellular damage. These changes cause a range of dementia symptoms, and the disease gradually worsens over time. Even newly diagnosed patients with mild to moderate AD have already suffered extensive irreversible damage to brain tissue, greatly limiting the effectiveness of clinical interventions. AD has a very insidious onset, with an incubation period that can be as long as 10 years or more. By the time a significant decline in cognitive ability is detected, the disease has already entered the middle to late stages. Considering that early detection and treatment can delay the onset of the disease by 5 years and reduce the incidence rate by nearly 50%, clinical research on AD has shifted its focus to early identification and prevention.

[0003] Numerous studies have shown that pathological changes in Alzheimer's disease (AD) occur far earlier than the onset of clinical symptoms; for example, Aβ deposition can begin 15-20 years before the clinical symptoms of AD appear. However, PET scans or cerebrospinal fluid biomarkers used to detect AD pathology are often excluded from routine medical examinations due to their invasiveness and high cost, causing people to miss the optimal time for diagnosis and treatment. Summary of the Invention

[0004] To overcome the shortcomings of existing methods, this invention provides an olfactory recognition method for preclinical screening of Alzheimer's disease.

[0005] The problem to be solved by the present invention is achieved through the following technical solution:

[0006] In this invention, eight female 3xTg mice (12 months old, n=8) and eight female C57BL / 6WT mice (12 months old, n=8) were first subjected to three olfactory tests to verify the difference in olfactory ability between AD mice and normal mice. The process includes the following steps: (1) Food burial test (2) Habituation and dehabituation test (3) Scent-Reward Association Memory Test

[0007] Then, the Chinese Smell Identification Test (CSIT) and the Montreal Cognitive Assessment (MoCA) were simultaneously applied to middle-aged and elderly populations in Chinese communities to analyze the correlation between CSIT-16 scores and MoCA scores. This included the following steps: (1) Recruiting subjects (2) Face-to-face interviews and cognitive function assessment (3) Olfactory function assessment

[0008] This invention primarily provides a theoretical basis for early screening of Alzheimer's disease through early olfactory lesions, utilizing olfactory recognition technology. This technology, used for pre-AD screening, can identify elderly individuals with subacute chronic dementia (SCD) at risk of developing AD, and has the function of screening middle-aged and elderly patients at risk of Alzheimer's disease.

[0009] Odor assessment technology, with its significant cost-effectiveness, completely non-invasive nature, and extremely simple operation, is expected to become a highly reliable tool for the initial detection of Alzheimer's disease in the future.

[0010] The experimental results showed significant differences in MOCA test sub-items, CSIT-OI scores, and CSIT-self scores among the four groups (p<0.0001). In the total sample, CSIT-OI scores were positively correlated with the total MoCA score and its sub-item scores (all P<0.0001). In the normal control (NC) group, CSIT-OI scores were positively correlated with delayed memory scores (P<0.05). In the mild cognitive impairment (MCI) group, CSIT-OI scores were not correlated with the total MoCA score and its sub-item scores (all P>0.05). In the moderate cognitive impairment group, the total MoCA score, naming, and language scores were positively correlated (P<0.05). In the severe cognitive impairment group, CSIT-OI scores were not correlated with the total MoCA score and its sub-item scores (all P>0.05). In the community population, olfactory recognition ability decreased with cognitive decline. Attached Figure Description

[0011] Figure 1 Technical roadmap for mouse olfactory testing

[0012] Figure 2 A technical roadmap for preclinical screening of Alzheimer's disease (AD) in middle-aged and elderly populations in Chinese communities.

[0013] Figure 3 Results of food burial tests in mice.

[0014] Figure 4 The results are from the habituation and dehabituation test in mice.

[0015] Figure 5 Results of an odor-reward association memory test for mice.

[0016] Table 1 shows the cognitive and olfactory function scores of middle-aged and elderly people in Chinese communities.

[0017] Table 2 shows the correlation analysis between CSIT scores and MoCA scores. Detailed Implementation

[0018] Example 1 (Technical solution see...) Figure 1 )

[0019] Materials and Methods

[0020] animal

[0021] Eight female 3xTg mice (12 months old, n=8) and eight female C57BL / 6WT mice (12 months old, n=8) participated in this study. The animals were housed in cages (30 cm × 20 cm × 15 cm; 3-4 mice per cage) under a 12-hour light cycle at 22°C. The cages contained bedding and a small polyethylene tube covered by a metal cage. The mice were allowed free access to food and tap water.

[0022] olfactory test

[0023] Food burial test

[0024] Before the experiment, food pellets were used instead of regular feed pellets to familiarize the mice with the taste of the food. Two days prior to the test, the mice were fed a restricted diet but allowed free access to water. The mice were fasted for 14 hours (lights were turned off starting at 8 PM), and the test was conducted under dim white light from 10:00 AM to 11:00 AM. The mice were placed in transparent test cages (42 cm × 25 cm × 25 cm), with food pellets buried 0.5 cm below the surface of the sawdust bedding. The mice were placed facing the cage wall. The location of the food pellets was randomly changed daily. The latency period was recorded from the moment the mice were placed in the cage until they grasped the food pellets with their forepaws or teeth. Recording was stopped after 5 minutes, which was set as the longest latency period. As a control, a visible pellet test was conducted with food pellets placed on the bedding surface, and the mice were allowed to consume the food pellets after the test.

[0025] Habituation and dehabituation test

[0026] Three days prior to the experiment, mice were acclimatized to the experimental conditions. These mice were then exposed to two different odors to test their olfactory discrimination ability. First, cotton swabs soaked in mineral oil were presented to the mice four times consecutively, each time for 1 minute, with a 1-minute interval. Then, propyl butyrate and isoamyl acetate were diluted to 1×10⁻³ with mineral oil and applied to cotton swabs. Each odor was presented to the mice four times, each time for 1 minute, with a 1-minute interval. The exploration time of the mice was recorded for each instance.

[0027] Scent-Reward Association Memory Test

[0028] For the first three days of training, the mice's food was restricted to reduce their body weight to 85-90% of their free-feeding body weight. To acclimate the mice to sugar rewards, a few small sugar cubes were placed in each mouse's home cage the day before training. Then, a four-day training period was completed. Mice were exposed to two odor cans diluted to 10⁻³ (dipentene, geraniol), one with sugar (S+) and the other without sugar (S-). On each training day, mice completed two S+ (sugar) odor tests and two S- (sugar-free) odor tests. The order of the S+ and S- tests varied by day and followed a pseudo-random order. For each training test (10 minutes), mice were allowed to explore the training cage and dig in the odor cans to obtain the sugar reward. In the memory test, S+ and S- odor cans containing the odorant but without sugar were used, with the two cans placed on opposite sides of the chamber. Mice were placed in the central chamber, and the time spent digging in the S+ and S- odor cans with paws or noses within 3 minutes was recorded. The memory of sugar-odor associations is calculated as the percentage of time spent mining S+ odors [(S+) / (S+)+(S-)]*100].

[0029] The test results are shown in the appendix. Figure 3 , 4 5:

[0030] like Figure 3 As shown, compared with 12m C57 mice, 12m 3xTg mice had a longer latency period in finding buried food, indicating that AD mice had a poorer odor detection ability; Figure 4 As shown, compared with 12m C57 mice, 12m 3xTg mice took longer to explore new odors and less time to explore them after becoming familiar with them, indicating that AD mice have poorer odor discrimination ability; Figure 5 As shown, there was no significant difference in the percentage of time spent by 2mC57 mice and 112m 3xTg mice in discovering S+ odors, indicating that there is little difference in odor memory ability between AD mice and normal mice after long-term memory training.

[0031] Example 2 (see technical solution) Figure 2 )

[0032] Subjects

[0033] Inclusion criteria included: 1) Age 50 years or older; 2) Willingness to join the study or consent from their guardian, and signing of the relevant informed consent form. Exclusion criteria included: 1) History of non-Alzheimer's dementia with a clear etiology; 2) History of severe anxiety disorder, depression, schizophrenia, or other mental illnesses with significant mental abnormalities; 3) History of systemic diseases that severely affect one's ability to live independently; 4) Long-term use of psychotropic medications; 5) History of head trauma with sequelae; 6) Refusal or inability to cooperate with cognitive function examinations; 7) Incomplete clinical data collection; 8) Presence of nasal polyps, deviated nasal septum, nasal tumors, or nasal trauma.

[0034] Face-to-face interviews and cognitive function assessment

[0035] Testers conducted interviews with participants to obtain general information, personal history, past medical history, and family medical history. Participants underwent the Montreal Cognitive Assessment (MoCA, Chinese Version) to assess their performance in seven cognitive domains: visuospatial and executive function, naming ability, attention, verbal repetition and fluency, abstract descriptive summarization ability, delayed memory, and orientation.

[0036] Olfactory function assessment

[0037] Olfactory perception was assessed using the Chinese Odor Identification Test-16 (CSIT-16). Sixteen olfactory identification test sticks (including orange, almond milk, garlic, chocolate, coffee, floral water, sesame oil, fried fish, banana, rose, fennel, apple, dried longan lemon, pineapple, and soy sauce) were used in conjunction with accompanying software to test the subjects' olfactory function. Each olfactory stick presented one odor, and the odors from different sticks were not repeated. In each test, one odor from one stick was presented, and the subject was asked to select the name of the odor from four options.

[0038] The test results are shown in Appendix 1 and 2:

[0039] As shown in Table 1, there were significant differences in MOCA test sub-items, CSIT-OI scores, and CSIT-self scores among the four groups (p < 0.0001). As shown in Table 2, in the total sample, CSIT-OI scores were positively correlated with the total MoCA score and its sub-item scores (all P < 0.0001). In the normal control (NC) group, CSIT-OI scores were positively correlated with delayed memory scores (P < 0.05). In the mild cognitive impairment (MCI) group, CSIT-OI scores were not correlated with the total MoCA score and its sub-item scores (all P > 0.05). In the moderate cognitive impairment group, the total MoCA score, naming, and language scores were positively correlated (P < 0.05). In the severe cognitive impairment group, CSIT-OI scores were not correlated with the total MoCA score and its sub-item scores (all P > 0.05). This indicates that in the community population, olfactory recognition ability declines with cognitive decline. Table 1 Table 2

[0040] The above embodiments merely illustrate the implementation of the present invention, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the present invention. Any technical solutions obtained by adopting equivalent substitutions or equivalent transformations should fall within the protection scope of the present invention.

Claims

1. An olfactory recognition method for preclinical screening of Alzheimer's disease, characterized in that, in animal experiments, Includes the following steps: (1) Select experimental animals: female 3xTg mice (12M, n=8) and female C57BL / 6WT mice (12M, n=8); (2) The latency period for mice to find buried food was obtained through the food burial test; (3) The time it takes for mice to explore new odors is obtained through habituation and dehabituation tests; (4) Obtain the percentage of time mice spent exploring S+ odors using the odor-reward association memory test; (5) Statistical analysis of the olfactory test results of the two groups of mice, and analysis of the mice’s ability to explore, distinguish and remember odors.

2. The method according to claim 1, wherein, In step (5), compared with 12m C57 mice, 12m 3xTg mice had a longer latency period in finding buried food, indicating that AD mice had a poorer odor detection ability; compared with 12m C57 mice, 12m 3xTg mice took longer to explore new odors and less time to explore after becoming familiar with the odor, indicating that AD mice had a poorer odor discrimination ability; there was no significant difference in the percentage of time spent by 12m C57 mice and 12m 3xTg mice in digging for S+ odors, indicating that AD mice and normal mice had little difference in odor memory ability after long-term memory training.

3. An olfactory recognition method for preclinical screening of Alzheimer's disease, in the field of epidemiology, characterized in that, Includes the following steps: (1) Subjects were selected based on inclusion criteria; (2) The subjects were grouped according to the Montreal Cognitive Assessment (MoCA) scoring criteria. (3) The olfactory function was assessed using the Chinese Smell Identification Test-16 (CSIT-16); (4) Analyze the correlation between CSIT-16 score and MoCA score through data statistics.

4. The method according to claim 3, wherein, There were significant differences in MOCA test sub-items, CSIT-OI scores, and CSIT-self scores among the four groups (p < 0.0001); In the total sample, the CSIT-OI score was positively correlated with the MoCA total score and its sub-item scores (all P < 0.0001). In the normal control group, the CSIT-OI score was positively correlated with delayed memory score (P < 0.05). In the mild cognitive impairment (MCI) group, the CSIT-OI score was not correlated with the MoCA total score and its sub-item scores (all P > 0.05). In the moderate cognitive impairment group, the MoCA total score, naming, and language scores were positively correlated (P < 0.05). In the severe cognitive impairment group, the CSIT-OI score was not correlated with the MoCA total score and its sub-item scores (all P > 0.05). This indicates that in the community population, olfactory recognition ability declines with cognitive decline, and CSIT-16 can be applied in preclinical screening for Alzheimer's disease.

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