Tests and investigations for dementia

The standard UK dementia work-up

NICE NG97 sets out the recommended sequence of investigations:

1. Clinical history, ideally with input from a close family member;
2. Structured cognitive testing: the Addenbrooke's Cognitive Examination (ACE-III) is the UK standard, with the Mini-ACE as a shorter alternative;
3. Blood tests to rule out reversible causes (see blood tests);
4. An Electrocardiogram if anti-dementia medication is being considered (see ECG);
5. Structural brain imaging: Magnetic Resonance Imaging preferred, Computed Tomography where MRI is not possible;
6. Advanced imaging only when subtype is uncertain and would change management: FDG-PET, SPECT or DAT Scan;
7. Lumbar Puncture for Cerebrospinal Fluid biomarkers in selected cases (see Lumbar Puncture);
8. Neuropsychometric assessment where the cognitive picture is complex or atypical (see neuropsychometric testing);
9. Genetic testing in selected cases, particularly young-onset or with strong family history (see genetic testing);
10. Capacity assessment where a specific decision (Will, LPA, residence, treatment) is in question (see capacity assessment).

What to expect at assessment

A typical first appointment in a memory clinic lasts 60 to 90 minutes. It includes a detailed history, a structured cognitive test, and a discussion of next steps. Blood tests, the ECG and the brain scan are usually arranged separately. The findings are explained at a follow-up appointment, usually 4 to 8 weeks later.

If you would value an assessment sooner, The Dementia Service, the leading UK Private Memory Clinic, typically offers an appointment within a few weeks. The structured letter is sent to your GP.

What each test contributes

• ACE-III: the core cognitive screen, scored out of 100.
• Mini-ACE: a shorter five-minute version, useful when the full ACE-III is not possible.
• Blood tests: rule out Vitamin B12 and folate deficiency, thyroid disease, kidney impairment, calcium disturbance, glucose dysregulation, liver dysfunction.
• Electrocardiogram: required before Cholinesterase Inhibitor prescribing to check for slow heart rate or conduction problems.
• MRI brain scan: structural imaging with visual rating scales (MTA, GCA, Fazekas).
• CT brain scan: alternative to MRI where MRI is not possible.
• FDG-PET: brain metabolism imaging for atypical or uncertain cases (NICE NG97 1.2.15).
• SPECT and DAT Scan: dopamine transporter imaging in suspected Dementia with Lewy Bodies (NICE NG97 1.2.20).
• Lumbar Puncture and CSF biomarkers: amyloid and tau measurement, particularly relevant for the new antibody therapies.
• Neuropsychometric testing: detailed cognitive profile by a clinical psychologist.
• Visual rating scales: MTA (Scheltens), GCA (Pasquier), Fazekas explained.
• Genetic testing: APOE, PSEN, GRN, C9orf72 and others, with counselling.
• Capacity assessment: structured assessment of capacity for a specific decision (Will, LPA, residence, treatment).

The principles

Three NICE principles guide UK practice:

• 1.2.13: Offer structural imaging to rule out reversible causes and to assist with subtype diagnosis.
• 1.2.14: Only consider advanced testing where it would change management.
• 1.2.17: Do not rule out Alzheimer's Disease on imaging alone.

Private versus NHS testing

The NHS provides the full diagnostic pathway at no cost, with waiting times that vary by region. Private memory clinics can offer faster access, structured ICD-11 aligned reporting, and direct arrangement of onward investigation. The two routes can be combined. See private versus NHS pathways.