The Future of Blood Testing for Alzheimer’s Diagnosis
A simple blood test may one day be the first step in diagnosing Alzheimer’s Disease (AD). Currently, the gold-standard methods to confirm AD are with an invasive cerebrospinal fluid collection or an expensive PET Scan. In March 2020, Thijssen, et al., studied the effectiveness of a blood test in diagnosing and differentiating between AD and other dementias, including Frontotemporal dementia (FTD).
The reason this drew my attention is because current preliminary AD screening tests are not perfect and can have educational, language and cultural biases. It can also be difficult to differentiate FTD from AD because they have similar impairments such as, difficulty organizing and planning, short-term memory problems or difficulty acclimating to social situations.
In Thijssen’s research, one protein, pTau181, which has previously been suggested as a biomarker for AD, was 3.5 times elevated in AD participants versus the healthy control group; while those with FTD had normal levels. The authors also found elevated pTau181 could predict the rate of cognitive decline in AD and those with Mild Cognitive Impairment within their 2-year follow up.
A second protein, NfL (neurofilament light chain) was found to be elevated for people with FTD compared to other groups. This protein helps neurons with structural support, but leaks into spinal fluid and blood when the neuron is damaged. Amyloid was the third protein tested and is the basis for PET scan screening; however, amyloid plasma levels were not found to be as accurate for indicating dementia as pTau181.
A similar trial by Janelidze, et al., (2020) was conducted on 589 individuals in Sweden. Their results also found pTau181 to be significantly elevated in the blood of people with AD compared to their control groups. Also of note, these elevated levels could be detected even during early stages of AD.
FTD consists of a spectrum of dementias and is one of the more common causes of early-onset dementia. The average age for FTD occurs at 58 years, but can occur between the ages of 20 and 80. The symptoms of AD typically begin mid-60s and early-onset AD can begin at age 30. The prevalence of early onset dementia is rare, but a misdiagnosis can result in mistaken referrals to psychiatric services and delayed access to dementia treatments.
What does all of this really mean? When I first began my formal education on dementia, AD diagnosis via cerebrospinal fluid or PET scans did not exist; it was only possible to confirm post-mortem. Advancements in biomarkers, such as pTau181 and NfL, give us the possibility of an easy, inexpensive blood test for diagnosing specific types of dementia. This means there is more hope: an earlier, accurate diagnosis means the possibility of improved clinical trials, enhanced treatment protocols and positive outcomes. The future is still bright!
Dr. Romi Fung, ND, M.Sc and Alaina King, M.Sc
Dr. Romi Fung, ND, M.Sc is a Naturopathic Physician practicing in Richmond, BC with clinical interests in working with patients living with dementia. Dr. Romi has completed additional training in the Bredesen Protocol for treating cognitive impairment, as well as graduate studies in Aging and Health. He is currently pursuing a Ph.D in Aging and Health from Queen's University and is an Adjunct Clinic Faculty at the Canadian College of Naturopathic Medicine - Boucher Campus.
Alaina has a MSc in Aging & Health and is the owner of Grey Matters Tx. A registered professional Recreation Therapist and Certified Dementia Practitioner, Alaina has been working with older adults with dementia since 1998. In addition to Recreation Therapy, Alaina has worked in Community Patient Care Coordination and as a Staff Educator and Health & Safety Auditor in Long Term Care.
Medical Disclaimer: This content is not intended to be a substitute for professional medical advice, diagnosis or treatment. Never disregard professional medical advice, or delay in seeking it, because of something you have read on this post.
Janelidze, S., Mattsson, N., Palmqvist, S., et al. (2020). Plasma P-tau181 in Alzheimer’s Disease: Relationship to Other Biomarkers, Differential Diagnosis, Neuropathology and Longitudinal Progression to Alzheimer’s Dementia. Natural Medicine, 26(3), 379-386.
Thijssen, E.H., La Joie, R., Wolf, A. et al. (2020). Diagnostic value of plasma phosphorylated tau181 in Alzheimer’s disease and frontotemporal lobar degeneration. Natural Medicine, 26(3), 387–397.