Abstract: There is provided a system for determining the state of dementia by using an image differentiation technique and a cognitive test score together with each other. A system includes: a first input module configured to acquire a first evaluation index based on data regarding the physical state of a brain of a subject; a second input module configured to acquire a second evaluation index based on data regarding the function of the brain of the subject; and an estimation module configured to estimate the state of dementia of the subject based on an evaluation value obtained by a first evaluation function having the first evaluation index and the second evaluation index as its variables.