Mild Cognitive Impairment (MCI)

What MCI is, and what it is not

Mild Cognitive Impairment (MCI), also written in ICD-11 as Mild Neurocognitive Disorder (6D71), is a syndrome in which:

• There is a noticeable change from your usual level of cognitive functioning;
• The change is confirmed by objective testing such as the ACE-III;
• The change is greater than expected for your age and education; and
• You remain able to perform your usual everyday activities independently.

That last point is the defining feature. The boundary between MCI and dementia in ICD-11 is functional, not radiological. If you still manage your finances, your medications, shopping, cooking, washing, dressing and continence without significant help, you do not meet the threshold for dementia even if your scan shows changes.

What MCI feels like

The most common pattern is amnestic MCI, where short-term memory is the main difficulty. People describe:

• Forgetting names and recent conversations more often than peers;
• Misplacing items and having to retrace steps;
• Needing to write things down where previously you would have remembered;
• Some word-finding pauses, particularly under stress or fatigue.

Less common patterns include MCI predominantly affecting attention, language, or visuospatial skill. These can point towards specific underlying processes and influence the long-term picture.

What causes MCI

MCI is a syndrome, not a single disease. The most common causes are:

• Early Alzheimer's Disease. Around half of amnestic MCI cases turn out to be early Alzheimer's, and the term "prodromal Alzheimer's" is sometimes used.
• Vascular Cognitive Impairment. Small Vessel Disease and previous strokes can produce MCI before any dementia threshold is reached.
• Mood, sleep and medication. Depression, anxiety, Sleep Apnoea, anticholinergic and sedative medicines, alcohol and recent illness all measurably reduce cognitive performance.
• Endocrine and nutritional factors. Thyroid disease, vitamin B12 deficiency, vitamin D insufficiency, folate deficiency and uncontrolled diabetes.
• Other neurodegenerative or neurological conditions including Lewy Body Disease, Parkinson's Disease, Frontotemporal Degeneration, hydrocephalus, head injury and rare neurological diseases.

What the prognosis looks like

Across population-based studies, roughly 17% to 25% of people with MCI progress to dementia within five years, with higher conversion in amnestic MCI and lower conversion when a reversible cause is identified and treated. Importantly, around a third of people with MCI remain stable, and a meaningful minority improve, particularly when an underlying mood, sleep or medication issue is addressed.

What helps

The evidence base for action in MCI is now substantial:

• Vascular risk reduction. Blood pressure control, lipid management, glycaemic control, smoking cessation and reduced alcohol all measurably reduce dementia risk. See our vascular risk page.
• Physical activity. 150 minutes of moderate-intensity activity each week, combined with two short resistance sessions, is associated with slower cognitive decline. See exercise.
• Diet. Mediterranean and MIND-style diets have the strongest associations with brain health. See diet and nutrition.
• Sleep. Treating Sleep Apnoea, where present, and addressing chronic insomnia, both improve cognition.
• Mental and social activity. Cognitive stimulation, learning new skills, social contact and meaningful activity each contribute.
• Hearing. If you have hearing loss, wearing hearing aids is associated with a meaningful reduction in dementia risk.
• Medication review. A GP-led review to reduce anticholinergic burden where possible.

Medication for MCI

Cholinesterase inhibitors such as Donepezil are not recommended for MCI; they are licensed for mild to moderate Alzheimer's Disease under NICE TA217. The newer antibody therapies Lecanemab and Donanemab are currently not recommended by NICE for routine NHS use. Future guidance may change this, which is one reason why structured follow-up of MCI matters.

That said, treating any underlying mood disorder, Sleep Apnoea or vitamin deficiency is part of standard MCI management, and may make a meaningful difference to cognitive performance.

Follow-up and monitoring

Most clinicians recommend a repeat assessment in 6 to 12 months, sooner if symptoms change. The next assessment compares ACE-III scores, functional status (a careful interview about activities of daily living) and, where indicated, repeat imaging. Stable scores over time are reassuring; declining scores prompt review of the diagnosis and consideration of progression.

It is helpful to keep your own notes between appointments: examples of memory or word-finding difficulty, sleep, mood, and any new physical symptoms.

If imaging looks heavy but you function well

It is common to see an MRI that shows medial temporal atrophy (an MTA grade of 1 to 2) or some Small Vessel Disease in a person who functionally is independent. ICD-11 is clear that the imaging burden does not determine the diagnostic threshold. The label remains Mild Neurocognitive Disorder while activities of daily living are preserved. The imaging finding is, however, useful for monitoring: it gives a baseline against which a future scan can be compared.

Where The Dementia Service fits in

If you are looking for prompt assessment, structured cognitive testing and a clear plan, The Dementia Service sees most adults within a few weeks. The clinic offers virtual consultations, structured letters that align with ICD-11 and NICE NG97, and supports onward investigation when needed. Working alongside your GP and any NHS pathway, this can shorten the time to a confident formulation and a plan.