Alzheimer’s — hope and hype

The New York Times headline was compelling: “‘Amazing, Isn’t It?’ Long-Sought Blood Test for Alzheimer’s in Reach.”

The article reports on research from the Journal of the American Medical Association (JAMA) which was presented at the Alzheimer’s Association International Conference this week.

In three samples of people from Sweden, Colombia and the United States, a protein called tau — specifically, P-tau217 — detected in a blood test was used to distinguish Alzheimer’s disease from other forms of dementia.

Given that more than 560,000 Canadians have dementia — a number expected to reach 937,000 by 2035 — any news of tests that can distinguish between types of dementia and thus offer hope for more specific and effective treatment is welcome.

Alzheimer’s is often diagnosed through clinical assessments. With psychiatrists in short supply and long wait times the norm in Canada, some people are only diagnosed after the disease has progressed considerably. Any test that can diagnose Alzheimer’s sooner would present better options for treatment. There is no cure.

Carolyn Harley, a neuroscience researcher and professor emeritus at Memorial University, says the research “should improve the chances of effective interventions before too much has gone wrong, as well as making accurate differential diagnosis of (Alzheimer’s disease) or other dementia conditions possible, premortem.”

She has a personal as well as a professional interest, having lost her mother and grandmother to dementia.

Among the Colombian test subjects — which included many people with a rare familial form of early-onset Alzheimer’s disease — the blood test could pinpoint Alzheimer’s in young people, 20 years before symptoms were expected to appear.

This interests Matt Parsons, an assistant professor of neuroscience at MUN, who researches neurodegenerative diseases and has funding from the Alzheimer Society of Canada.

“This predictive potential of the test was an extremely exciting result for me to read; if we know who is destined to develop Alzheimer’s disease, then neuroprotective strategies can be initiated early,” he said.

“What makes this finding even more exciting is the fact that these P-tau217 levels can be detected in the blood. Prior to this study, other known markers with high diagnostic accuracy require MRI or PET imaging, or extraction of the patient’s cerebrospinal fluid.”

Dr. Kenneth Rockwood, who specializes in geriatric medicine and neurology and is the Kathryn Allen Weldon Professor of Alzheimer Research at Dalhousie University, says while the research is promising, it’s too soon to say whether it will lead to a predictive tool for widespread use.

“I’ve been looking at Alzheimer disease studies since the 1980s,” Rockwood told SaltWire Network. “What I have learned is to be very cautious about early results. … The primary outcome is a comparison with people who are known to have a neurodegenerative disease. How that will play out in ordinary people who are referred to a memory clinic is not clear…

“That is why we have to be careful, and view these results as interesting, even promising, but (not quite) the whole story.”

Sometimes, an abundance of hope can lead to hype. Nonetheless, this is research worth watching.