In plain English
Dementia diagnoses are now written using ICD-11, the World Health Organization's 2022 classification, alongside familiar names such as Alzheimer's or Vascular Dementia. This page translates the codes and severity terms into plain English, so the letter from the memory clinic makes sense at first reading.
Why the letter uses codes
From January 2022 the UK has been adopting ICD-11, the eleventh revision of the World Health Organization's International Classification of Diseases. Memory clinics, including The Dementia Service and many NHS services, now record the precise diagnostic category and a severity descriptor. The benefit to you is precision: a 6D80.2 Mixed Alzheimer's and Vascular Dementia diagnosis is meaningfully different from a 6D81 pure Vascular Dementia, and the implications for treatment and follow-up are different.
The diagnosis usually appears at the start of the Impression section of your letter. It may look like:
"ICD-11 6D80.2 – Alzheimer's Disease Dementia, Mixed Type, with Cerebrovascular Disease, mild in degree."
That single line tells the next clinician who reads the letter: the underlying disease, the presence of vascular contribution, and the current severity.
The common ICD-11 dementia categories, in plain English
6D80 — Alzheimer's Disease dementia
This is the most common dementia. It typically begins with insidious short-term memory loss and word-finding difficulty, with later involvement of executive function, language and visuospatial skill. Two sub-codes refine the onset:
- 6D80.0 Early-onset, when symptoms begin before age 65. Genetic factors contribute in a minority of these cases.
- 6D80.1 Late-onset, when symptoms begin from age 65 onward. This is by far the most common form.
6D80.2 — Mixed Alzheimer's with Cerebrovascular Disease
Around a third of older adults with dementia have both Alzheimer's Pathology and Small Vessel Disease, infarcts or other cerebrovascular contribution on imaging. The label 6D80.2 captures this. The practical implication is that both anti-dementia medication (if tolerated) and aggressive vascular risk reduction are relevant.
6D81 — Vascular Dementia
Where the cognitive picture is driven mainly by Cerebrovascular Disease, sometimes with a stroke at onset. The cognitive profile tends to emphasise slowed thinking, attention and executive function. Treatment focuses on the underlying vascular risk factors.
6D82 — Dementia with Lewy Bodies
Less common but important. Suggestive features include fluctuating cognition, visual hallucinations, REM Sleep Behaviour Disorder, and parkinsonian signs. Some medicines used for behavioural symptoms in Alzheimer's are unsafe in Lewy Body Dementia, so getting this label right matters.
6D83 — Frontotemporal Dementia (FTD)
An umbrella term covering several variants: Behavioural Variant FTD (changes in personality, judgment and social conduct), and three forms of Primary Progressive Aphasia (non-fluent, semantic, logopenic). Memory is often relatively preserved in early FTD.
6D71 — Mild Neurocognitive Disorder (MCI)
You may also see "Mild Cognitive Impairment" or MCI. The 6D71 label means there is a measurable cognitive change that does not significantly interfere with everyday independence. Around a quarter of people with MCI progress to dementia within five years, so close monitoring is recommended.
"No diagnosis of dementia"
If the assessment finds no neurodegenerative condition, the letter will say so. The clinician will then explore other reasons for the symptoms: mood disorders, Sleep Apnoea, hearing loss, vascular risk, medication side effects, vitamin deficiencies, or simply normal age-related change.
What "mild", "moderate" and "severe" mean
Severity is decided by how much the cognitive impairment interferes with day-to-day life, not by the imaging or by the cognitive score in isolation.
- Mild dementia. Everyday tasks like dressing, eating and toileting are independent. There may be some difficulty with complex tasks such as managing finances or unfamiliar travel. Many people in this stage continue to live alone with light family support.
- Moderate dementia. Help is needed with several everyday activities, often including reminders for medication, support with shopping and cooking, and supervision around the home for safety.
- Severe dementia. Substantial support is needed for most daily activities, including personal care, eating and continence.
Severity descriptions can change over time, both in response to treatment and as the underlying condition progresses.
How the diagnosis is reached
UK memory clinics follow NICE NG97. A robust diagnostic process includes a careful history (including from a family member), a structured cognitive test such as the ACE-III, blood tests to rule out reversible causes, an ECG before considering anti-dementia medication, and structural neuroimaging (MRI preferred, or CT). Where uncertainty remains, advanced imaging such as FDG-PET or 123I-FP-CIT SPECT may be requested.
Imaging is supportive but not definitive. NICE NG97 1.2.17 states explicitly that Alzheimer's should not be ruled out on imaging alone. Equally, imaging burden does not by itself upgrade an MCI diagnosis to dementia; the threshold is functional, not radiological.
What if you disagree with the diagnosis?
It is reasonable, and not uncommon, to want a second opinion. Options include returning to your GP to request review, asking for a referral to a regional cognitive disorders clinic, or seeking a private assessment. The Dementia Service can review the existing letter and, where indicated, perform a fresh assessment with the most up-to-date investigations.
How the diagnosis affects insurance, work and driving
A dementia diagnosis must be declared to the DVLA. It also typically needs to be declared to motor and life insurers, and may affect travel insurance. It does not automatically mean stopping work; the Equality Act 2010 protects against discrimination and requires reasonable adjustments. We cover these in our practical matters section.
When and how to break the news
Telling family, friends and an employer takes time and thought. There is no single right way. Some people prefer to share early and openly, others wait until they have processed the news themselves. A short written summary, drawn from the assessment letter, often helps. Many people also share access to the letter with their GP, with a single trusted family member, and with one close friend, before widening the circle.
Frequently asked questions
Are the ICD-11 codes used by both private and NHS clinics?
Yes. UK NHS memory services and private clinics both use ICD-11. The codes are universal, which makes referrals and second opinions simpler.
Why does my letter mention both Alzheimer's and vascular?
Mixed Alzheimer's and Vascular Dementia (ICD-11 6D80.2) is the most common pattern in older adults and reflects the way both diseases tend to co-occur. The implications for treatment are the same as for Alzheimer's, with added emphasis on vascular risk reduction.
If imaging is normal, can I still have dementia?
Yes. NICE NG97 explicitly says Alzheimer's should not be ruled out on imaging alone. Some dementias, including Lewy body and early frontotemporal forms, can show only subtle structural changes.
What does 'mild' actually mean in practice?
Mild dementia means cognitive impairment is present but everyday independence is preserved. Many people in this stage continue to live alone, drive (with DVLA agreement), and manage their finances and medications, often with light family support.
How often will the diagnosis be reviewed?
Most UK clinics review at 6 to 12 months, then annually, with earlier review if symptoms change. The diagnosis can be refined or restaged as the condition evolves.
References
- World Health Organization. ICD-11 Chapter 06: Mental, behavioural and neurodevelopmental disorders, Neurocognitive disorders. 2026 release.
- National Institute for Health and Care Excellence. NICE guideline NG97: Dementia, assessment, management and support. London; 2018.
- McKeith IG, Boeve BF, Dickson DW, et al. Diagnosis and management of Dementia with Lewy Bodies. Neurology 2017;89(1):88-100.
- Rascovsky K et al. Sensitivity of revised diagnostic criteria for Behavioural Variant FTD. Brain 2011;134(Pt 9):2456-2477.