Diagnosing Alzheimer's disease: are we any nearer to useful biomarker-based, non-invasive tests?

Background: Alzheimer's disease (AD) accounts for 60-80% of cases of dementia and causes significant morbidity in patients and carers, and expense for health and social services. There is a need for a validated, non-invasive and cheap test to diagnose early AD, as diagnosis may enable prompt treatment and service planning. Aim: To identify emerging biomarker-based tests for the early diagnosis of AD which could be available for use in primary or generalist care in the near future.Design: Horizon scanning review.Methods: We searched online sources to identify emerging non-invasive, biomarker-based tests. Tests were included if they used blood, saliva or urine; and there was evidence of use in trials in patients with AD. For tests licensed for use in clinical or research settings we requested information from the developer on the intended place of use and plans for availability in Europe.Results: We identified 6 biomarker-based tests of which 5 are available for research or clinical use. The closest to market were AclarusDX(TM) (ExonHit Therapeutics) a gene signature test, and INNO-BIA plasma Abeta forms assay (Innogenetics N.V.) which may be CE marked for clinical use in 2015. We found no evidence of clinical utility or cost.Conclusion: Although biomarker-based tests are nearing clinical availability and may have a future role to help target AD-specific treatment and guide prognosis, they are not yet ready for trials of clinical utility in primary care