Stratification method and stratification device

A stratification method comprising:

• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying, wherein
• the hippocampus volume of each of the plurality of subjects is a right hippocampus volume of each of the plurality of subjects,
• the clinical psychological test is a preclinical Alzheimer's cognitive composite test,
• in the classifying, for each of the plurality of subjects, the subject is classified into the first group if the score of the subject is less than a first threshold and the right hippocampus volume of the subject is less than a second threshold, and classified into the second group if the score of the subject is greater than the first threshold and the right hippocampus volume of the subject is greater than the second threshold,
• the first threshold is 0.111±1 SD,
• the second threshold is 3.651±1 SD [cm3],
• the 1 SD of the first threshold is 2.630, and
• the 1 SD of the second threshold is 0.653 [cm3].

A stratification method comprising:

• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying, wherein
• the hippocampus volume of each of the plurality of subjects is a right hippocampus volume of each of the plurality of subjects,
• the clinical psychological test includes an Alzheimer's disease assessment scale-cognitive subscale test and a preclinical Alzheimer's cognitive composite test,
• the obtaining includes further obtaining, for each of the plurality of subjects, information indicating whether the subject is an apolipoprotein Eε4 gene carrier,
• in the classifying, for each of the plurality of subjects, the subject is classified into the first group in any of the following cases:
• (1) if a first score obtained as a result of the Alzheimer's disease assessment scale-cognitive subscale test performed on the subject is less than a first threshold, the right hippocampus volume of the subject is greater than a second threshold, the information indicates the subject is an apolipoprotein Eε4 gene carrier, and a second score obtained as a result of the preclinical Alzheimer's cognitive composite test performed on the subject is less than a third threshold, the first score being the score;
• (2) if the first score of the subject is greater than the first threshold, the right hippocampus volume of the subject is greater than the second threshold, the information indicates the subject is an apolipoprotein Eε4 gene carrier, and the second score of the subject is less than the third threshold;
• (3) if the first score of the subject is greater than the first threshold and the right hippocampus volume of the subject is less than the second threshold;
• or
• (4) if the first score of the subject is less than the first threshold, the right hippocampus volume of the subject is less than the second threshold, the information indicates the subject is an apolipoprotein Eε4 gene carrier, and the second score of the subject is less than the third threshold, and
• classified into the second group in any of the following cases:
• (5) if the first score of the subject is less than the first threshold, the right hippocampus volume of the subject is greater than the second threshold, the information indicates the subject is an apolipoprotein Eε4 gene carrier, and the second score of the subject is greater than the third threshold;
• (6) if the first score of the subject is greater than the first threshold, the right hippocampus volume of the subject is greater than the second threshold, the information indicates the subject is an apolipoprotein Eε4 gene carrier, and the second score of the subject is greater than the third threshold;
• or
• (7) if the first score of the subject is less than the first threshold, the right hippocampus volume of the subject is greater than the second threshold, and the information indicates the subject is not an apolipoprotein Eε4 gene carrier,
• the first threshold is 20.0±1 SD,
• the second threshold is 3.651±1 SD [cm3],
• the third threshold is 0.111±1 SD,
• the 1 SD of the first threshold is 6.3,
• the 1 SD of the second threshold is 0.653 [cm3], and
• the 1 SD of the third threshold is 2.630.

A stratification method comprising:

• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying, wherein
• each of the plurality of subjects has a positive beta-amyloid brain PET scan,
• the hippocampus volume of each of the plurality of subjects is a left hippocampus volume of each of the plurality of subjects,
• the clinical psychological test is an Alzheimer's disease assessment scale-cognitive subscale test,
• in the classifying, for each of the plurality of subjects, the subject is classified into the first group if the score of the subject is greater than a first threshold and the left hippocampus volume of the subject is less than a second threshold, and classified into the second group if the score of the subject is less than the first threshold and the left hippocampus volume of the subject is greater than the second threshold,
• the first threshold is 14.0±1 SD,
• the second threshold is 3.459±1 SD [cm3],
• the 1 SD of the first threshold is 6.9, and
• the 1 SD of the second threshold is 0.5435 [cm3].

A stratification method comprising:

• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying, wherein
• each of the plurality of subjects has a positive beta-amyloid brain PET scan,
• the hippocampus volume of each of the plurality of subjects is a left hippocampus volume of each of the plurality of subjects,
• the clinical psychological test is an Alzheimer's disease assessment scale-cognitive subscale test,
• in the classifying, for each of the plurality of subjects, the subject is classified into the first group if the score of the subject is greater than a first threshold and the left hippocampus volume of the subject is less than a second threshold, and classified into the second group if the score of the subject is less than the first threshold and the left hippocampus volume of the subject is greater than the second threshold,
• the first threshold is 12.0, and
• the second threshold is 3.737 [cm3].

A stratification method comprising:

• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying, wherein
• each of the plurality of subjects has a positive beta-amyloid brain PET scan,
• the hippocampus volume of each of the plurality of subjects is a left hippocampus volume of each of the plurality of subjects,
• the clinical psychological test is an Alzheimer's disease assessment scale-cognitive subscale test,
• in the classifying, for each of the plurality of subjects, the subject is classified into the first group if the score of the subject is greater than a first threshold and the left hippocampus volume of the subject is less than a second threshold, and classified into the second group if the score of the subject is less than the first threshold and the left hippocampus volume of the subject is greater than the second threshold,
• the first threshold is 21.0, and
• the second threshold is 3.080 [cm3].

A stratification method comprising:

• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying, wherein
• each of the plurality of subjects has a positive beta-amyloid brain PET scan,
• the hippocampus volume of each of the plurality of subjects is a left hippocampus volume of each of the plurality of subjects,
• the clinical psychological test is an Alzheimer's disease assessment scale-cognitive subscale test,
• in the classifying, for each of the plurality of subjects, the subject is classified into the first group if the score of the subject is greater than a first threshold and the left hippocampus volume of the subject is less than a second threshold, and classified into the second group if the score of the subject is less than the first threshold and the left hippocampus volume of the subject is greater than the second threshold,
• the first threshold is 24.0, and
• the second threshold is 2.751 [cm3].

A stratification method comprising:

• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying, wherein
• each of the plurality of subjects has a positive beta-amyloid brain PET scan,
• the hippocampus volume of each of the plurality of subjects is a left hippocampus volume of each of the plurality of subjects,
• the clinical psychological test is an Alzheimer's disease assessment scale-cognitive subscale test, and
• in the classifying, for each of the plurality of subjects, a volume score value indicating a ratio between the left hippocampus volume of the subject and the score of the subject is calculated, and each of the plurality of subjects is classified into one of the plurality of groups based on the calculated volume score value.

A stratification method comprising:

• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying, wherein
• the hippocampus volume of each of the plurality of subjects is a left hippocampus volume of each of the plurality of subjects,
• the clinical psychological test is an Alzheimer's disease assessment scale-cognitive subscale test, and
• in the classifying, for each of the plurality of subjects, a volume score value indicating a ratio between the left hippocampus volume of the subject and the score of the subject is calculated, and each of the plurality of subjects is classified into one of the plurality of groups based on the calculated volume score value.

A stratification device comprising:

• a processor;
• and
• memory storing a program, wherein
• when executed by the processor, the program causes the processor to perform:
• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying,
• the hippocampus volume of each of the plurality of subjects is a right hippocampus volume of each of the plurality of subjects,
• the clinical psychological test is an Alzheimer's disease assessment scale-cognitive subscale test,
• the classifying includes, for each of the plurality of subjects, classifying the subject into the first group if the score of the subject is greater than a first threshold and the right hippocampus volume of the subject is less than a second threshold, and classifying the subject into the second group if the score of the subject is less than the first threshold and the right hippocampus volume of the subject is greater than the second threshold,
• the first threshold is 20.0±1 SD,
• the second threshold is 3.651±1 SD [cm3],
• the 1 SD of the first threshold is 6.3, and
• the 1 SD of the second threshold is 0.653 [cm3].

A stratification device comprising:

• a processor;
• and
• memory storing a program, wherein
• when executed by the processor, the program causes the processor to perform:
• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying,
• the clinical psychological test is a preclinical Alzheimer's cognitive composite test,
• the classifying included, for each of the plurality of subjects, classifying the subject into the first group if the score of the subject is less than a first threshold and a right hippocampus volume of the subject is less than a second threshold, and classifying the subject into the second group if the score of the subject is greater than the first threshold and the right hippocampus volume of the subject is greater than the second threshold,
• the first threshold is 0.111±1 SD,
• the second threshold is 3.651±1 SD [cm3],
• the 1 SD of the first threshold is 2.630, and
• the 1 SD of the second threshold is 0.653 [cm3].

A stratification device comprising:

• a processor;
• and
• memory storing a program, wherein
• when executed by the processor, the program causes the processor to perform:
• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying,
• the hippocampus volume of each of the plurality of subjects is a right hippocampus volume of each of the plurality of subjects,
• the clinical psychological test includes an Alzheimer's disease assessment scale-cognitive subscale test and a preclinical Alzheimer's cognitive composite test,
• the obtaining includes obtaining, for each of the plurality of subjects, information indicating whether the subject is an apolipoprotein Eε4 gene carrier, and
• the classifying includes, for each of the plurality of subjects, classifying the subject into the first group in any of the following cases:
• (1) if a first score obtained as a result of the Alzheimer's disease assessment scale-cognitive subscale test performed on the subject is less than a first threshold, the right hippocampus volume of the subject is greater than a second threshold, the information indicates the subject is an apolipoprotein Eε4 gene carrier, and a second score obtained as a result of the preclinical Alzheimer's cognitive composite test performed on the subject is less than a third threshold, the first score being the score;
• (2) if the first score of the subject is greater than the first threshold, the right hippocampus volume of the subject is greater than the second threshold, the information indicates the subject is an apolipoprotein Eε4 gene carrier, and the second score of the subject is less than the third threshold;
• (3) if the first score of the subject is greater than the first threshold and the right hippocampus volume of the subject is less than the second threshold;
• or
• (4) if the first score of the subject is less than the first threshold, the right hippocampus volume of the subject is less than the second threshold, the information indicates the subject is an apolipoprotein Eε4 gene carrier, and the second score of the subject is less than the third threshold, and
• classifying the subject into the second group in any of the following cases:
• (5) if the first score of the subject is less than the first threshold, the right hippocampus volume of the subject is greater than the second threshold, the information indicates the subject is an apolipoprotein Eε4 gene carrier, and the second score of the subject is greater than the third threshold;
• (6) if the first score of the subject is greater than the first threshold, the right hippocampus volume of the subject is greater than the second threshold, the information indicates the subject is an apolipoprotein Eε4 gene carrier, and the second score of the subject is greater than the third threshold;
• or
• (7) if the first score of the subject is less than the first threshold, the right hippocampus volume of the subject is greater than the second threshold, and the information indicates the subject is not an apolipoprotein Eε4 gene carrier,
• the first threshold is 20.0±1 SD,
• the second threshold is 3.651±1 SD [cm3],
• the third threshold is 0.111±1 SD,
• the 1 SD of the first threshold is 6.3, and
• the 1 SD of the second threshold is 0.653 [cm3], and
• the 1 SD of the third threshold is 2.630.

A stratification device comprising:

• a processor;
• and
• memory storing a program, wherein
• when executed by the processor, the program causes the processor to perform:
• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying,
• each of the plurality of subjects has a positive beta-amyloid brain PET scan,
• the hippocampus volume of each of the plurality of subjects is a left hippocampus volume of each of the plurality of subjects,
• the clinical psychological test is an Alzheimer's disease assessment scale-cognitive subscale test,
• the classifying includes, for each of the plurality of subjects, classifying the subject into the first group if the score of the subject is greater than a first threshold and the left hippocampus volume of the subject is less than a second threshold, and classifying the subject into the second group if the score of the subject is less than the first threshold and the left hippocampus volume of the subject is greater than the second threshold,
• the first threshold is 14.0±1 SD,
• the second threshold is 3.459±1 SD [cm3],
• the 1 SD of the first threshold is 6.9, and
• the 1 SD of the second threshold is 0.5435 [cm3].

A stratification device comprising:

• a processor;
• and
• memory storing a program, wherein
• when executed by the processor, the program causes the processor to perform:
• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying,
• each of the plurality of subjects has a positive beta-amyloid brain PET scan,
• the hippocampus volume of each of the plurality of subjects is a left hippocampus volume of each of the plurality of subjects,
• the clinical psychological test is an Alzheimer's disease assessment scale-cognitive subscale test,
• the classifying includes, for each of the plurality of subjects, classifying the subject into the first group if the score of the subject is greater than a first threshold and the left hippocampus volume of the subject is less than a second threshold, and classifying the subject into the second group if the score of the subject is less than the first threshold and the left hippocampus volume of the subject is greater than the second threshold,
• the first threshold is 12.0, and
• the second threshold is 3.737 [cm3].

A stratification device comprising:

• a processor;
• and
• memory storing a program, wherein
• when executed by the processor, the program causes the processor to perform:
• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying,
• each of the plurality of subjects has a positive beta-amyloid brain PET scan,
• the hippocampus volume of each of the plurality of subjects is a left hippocampus volume of each of the plurality of subjects,
• the clinical psychological test is an Alzheimer's disease assessment scale-cognitive subscale test,
• the classifying includes, for each of the plurality of subjects, classifying the subject into the first group if the score of the subject is greater than a first threshold and the left hippocampus volume of the subject is less than a second threshold, and classifying the subject into the second group if the score of the subject is less than the first threshold and the left hippocampus volume of the subject is greater than the second threshold,
• the first threshold is 21.0, and
• the second threshold is 3.080 [cm3].

A stratification device comprising:

• a processor;
• and
• memory storing a program, wherein
• when executed by the processor, the program causes the processor to perform:
• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying,
• each of the plurality of subjects has a positive beta-amyloid brain PET scan,
• the hippocampus volume of each of the plurality of subjects is a left hippocampus volume of each of the plurality of subjects,
• the clinical psychological test is an Alzheimer's disease assessment scale-cognitive subscale test,
• the classifying includes, for each of the plurality of subjects, classifying the subject into the first group if the score of the subject is greater than a first threshold and the left hippocampus volume of the subject is less than a second threshold, and classifying the subject into the second group if the score of the subject is less than the first threshold and the left hippocampus volume of the subject is greater than the second threshold,
• the first threshold is 24.0, and
• the second threshold is 2.751 [cm3].

A stratification device comprising:

• a processor;
• and
• memory storing a program, wherein
• when executed by the processor, the program causes the processor to perform:
• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying,
• each of the plurality of subjects has a positive beta-amyloid brain PET scan,
• the hippocampus volume of each of the plurality of subjects is a left hippocampus volume of each of the plurality of subjects,
• the clinical psychological test is an Alzheimer's disease assessment scale-cognitive subscale test, and
• the classifying includes, for each of the plurality of subjects, calculating a volume score value indicating a ratio between the left hippocampus volume of the subject and the score of the subject, and classifying each of the plurality of subjects into one of the plurality of groups based on the calculated volume score value.

A stratification device comprising:

• a processor;
• and
• memory storing a program, wherein
• when executed by the processor, the program causes the processor to perform:
• obtaining, for each of a plurality of subjects with mild cognitive impairment, a score of a result of a clinical psychological test performed on the subject and a hippocampus volume of the subject, the hippocampus volume of the subject being obtained by performing a Magnetic Resonance Imaging (MRI) test on the subject to obtain to an MRI image of the subject, and measuring the hippocampus volume of the subject using the MRI image of the subject;
• classifying each of the plurality of subjects into one of a plurality of groups based on the score of the subject and the hippocampus volume of the subject, the plurality of groups including at least a first group at a relatively high risk of future progression to Alzheimer's disease and a second group at a relatively low risk of future progression to Alzheimer's disease;
• and
• outputting a classification result of the classifying,
• the hippocampus volume of each of the plurality of subjects is a left hippocampus volume of each of the plurality of subjects,
• the clinical psychological test is an Alzheimer's disease assessment scale-cognitive subscale test, and
• the classifying includes, for each of the plurality of subjects, calculating a volume score value indicating a ratio between the left hippocampus volume of the subject and the score of the subject, and classifying each of the plurality of subjects into one of the plurality of groups based on the calculated volume score value.