REAl World Dementia OUTcomes: Observational Study

Dementia affects a growing number of people in the UK, with significant costs for individuals, families, and society. There is an urgent need for accurate diagnosis of dementia to allow early intervention and support when people can still make decisions about their care.

Current dementia diagnosis in memory clinics relies on clinical assessment, cognitive testing, and brain scans (MRI or CT). Only a small proportion of UK patients have access to more specific tests like PET brain scans or spinal fluid analysis, which are expensive and not widely available.

Recent developments have shown that blood tests can accurately detect the underlying brain changes of dementia, particularly Alzheimer's disease. In research studies, these blood-based biomarkers (ptau217, AB42/40 ratio, GFAP, NFL etc) have successfully identified people with Alzheimer's disease when compared to clinical diagnoses, gold standard brain scans, and post-mortem brain examination. These blood tests also show promise for predicting people with future dementia risk.

However, most research has been conducted in younger, less diverse populations than those seen in real-world memory services. Blood-based biomarkers are not yet used in routine NHS practice, and more work is needed to test how well they perform in representative UK populations. We also need to understand whether people want to know their blood test results, what information they want, and how this is best communicated.

The READ-OUT study will test blood-based biomarkers in people attending memory clinics across the UK (30 NHS sites), ensuring participants represent the full diversity of people with dementia or memory concerns (30% from underrepresented groups). Participants will provide a 40ml blood sample and complete questionnaires about quality of life, healthcare use, and attitudes toward blood testing for dementia. The accuracy of blood biomarkers will be compared against established diagnostic methods including expert clinical review, brain scans, spinal fluid tests, and long-term health record follow-up.

The study includes three optional sub-studies: test-retest reliability of blood biomarkers (10% of participants returning after 1-2 weeks), investigating disease progression over one year (20% of participants), and evaluating whether people can collect blood samples at home using finger-prick cards (75 participants).

The study will determine which blood biomarkers are most accurate for diagnosing different types of dementia, predict disease progression, and assess their cost-effectiveness in the healthcare system. Results will inform whether these tests should be integrated into NHS clinical pathways and will guide the design of READ-OUT Phase 2, a randomized trial testing whether providing blood biomarker results to patients and doctors improves clinical care and outcomes.

• Disease prediction utility of blood-based biomarkers in diverse cognitive disorders populations [Time frame: baseline and at 52 weeks]
• Optimal individual or sets of biomarkers for separate dementia aetiologies [Time frame: baseline, at 2 weeks and 52 weeks]
• Impact of sample processing delays on the accuracy of blood biomarkers [Time frame: Baseline study visit]
• The test-retest reliability of blood biomarkers [Time frame: Baseline study visit, 1-2 week visit]
• The utility of remote blood test kits [Time frame: Baseline study visit]
• Understanding participant preferences on disclosure of biomarker status in dementia diagnosis [Time frame: baseline and at 52 weeks]