The International Classification of Diseases, 10th Revision (ICD-10) is a system that healthcare professionals use to classify and store information on diseases and other health problems.
The ICD-10 criteria for MID is: "F01.1 Gradual in onset, following a number of transient ischemic episodes, which produce an accumulation of infarcts in the cerebral parenchyma. Predominantly cortical dementia."
In other words, healthcare professionals classify MID as a gradual progression of dementia with several strokes in the cerebral cortex, which is the "thinking" area of the brain.