Mild cognitive impairment

Mild cognitive impairment (MCI) describes a state where someone's cognition has declined more than expected for their age and education, but not severely enough to qualify as dementia. They can usually still manage their own affairs, just less easily than before.

MCI is not a single disease. It is a clinical category that captures the borderline space between healthy ageing and a dementia diagnosis.

How it's identified

A typical MCI workup includes:

• A subjective complaint, where the person, a family member, or a clinician notices the decline
• Objective cognitive testing showing impairment in one or more domains, often using the MoCA or MMSE
• Preserved daily function
• Absence of full dementia

Subtypes

MCI is often divided by which cognitive domain is affected:

• Amnestic MCI, where memory is predominantly impaired, is more likely to progress to Alzheimer's disease
• Non-amnestic MCI, affecting other domains like executive function, language, or visuospatial skills, can progress to vascular dementia, Lewy body dementia, or frontotemporal dementia
• Multiple-domain MCI affects more than one area

What happens next

Outcomes vary. Roughly:

• About 10 to 15 percent of people with MCI progress to dementia each year
• A meaningful subset remain stable or even revert to normal cognition over several years
• The trajectory depends on the underlying cause (vascular, neurodegenerative, depressive, metabolic, medication-related)

Why imaging matters

Structural MRI can flag specific patterns that increase the likelihood of progression. Disproportionate hippocampal atrophy, accelerated brain age, or significant white matter hyperintensity burden all carry prognostic weight.

Identifying MCI early matters because it is the window where lifestyle and treatment intervention is most likely to slow progression.