Are blood tests for Alzheimer’s a “misguided waste of money”?
By Patrick Holford
You may have heard of a search for new tests to find those most likely to get Alzheimer’s disease. But is this misdirected?
Perhaps so, according to the Alzheimer’s Prevention Expert Group (APEG) - a collaboration of top UK, American and Chinese academics who consider this to be “..a misguided waste of money”.
Controversially, their stance challenges the major thrust of charities such as Alzheimer’s Research (ARUK), which strongly supports the search for a reliable test for the disease.
APEG explains that there is already a widely used way to spot failing memory and thinking skills - hallmarks of dementia and Alzheimer’s. These include a neuropsychological test battery (NTB) and a Cognitive Function Test (CFT). Both are routinely used in memory clinics to diagnose mild cognitive impairment and support the diagnosis of dementia.
Over the last decade, World Council for Health partner, the charity foodforthebrain.org has used the CFT to find people at risk and advise them on how to reduce their risk with simple dietary and lifestyle changes. They have already tested nearly half a million people to date!
Cognitive function declines steadily from the age of 18. This means that it is possible to spot individuals whose cognitive function is dropping off faster than the average, giving time to encourage preventative actions with personalised advice on their diet and lifestyle changes.
Alzheimer’s, which makes up two-thirds of dementia cases, involves the shrinking of certain areas of the brain as neurons die off. It can be detected with a specialised brain scan several years before a diagnosis. These ‘PET’ scans can be used to diagnose Alzheimer’s and/or vascular dementia. The trouble is that such scans are expensive and not likely performed early enough to discover those ‘at risk’.
As well as shrinkage, another marker for Alzheimer’s is a toxic protein called p-tau. This creates clumps of tangled nerves in the brain. These can be found in the fluid that bathes the brain but again there is a problem. Detecting it can be done with a lumbar puncture, but this is a risky and expensive process and certainly not suitable to test tens of thousands of people.
At first sight, if a blood test could identify those heading towards Alzheimer’s earlier this could be a cheaper and less invasive alternative to such scans. However, the search is likely driven by a quite different ulterior motive - to create and sell drugs – much like cholesterol and statins. What’s more it’s unlikely to be an improvement!
A recent New York Times article pointed out that, such a test would result in people being diagnosed with ‘pre’ Alzheimer’s, even if they have no obvious symptoms. That’s because having the marker would be considered enough to justify a diagnosis of the disease or, at least, the prescription of a drug.
This is what happens with amyloid protein. Amyloid forms plaque in the brains of those with Alzheimer’. The latest drugs, such as lecanemab and aducanumab, remove this. But not all those with Alzheimer’s have plaque, and people can develop dementia without plaque. What’s more none of these drugs have a clinically significant effect, and they come with the risk of severe adverse effects, including death from brain bleeding and swelling, especially in those with history of stroke.
Perhaps the most convincing reason why the new blood marker hunt is “misguided” is that there is something very cheap and very safe that can prevent the accumulation of p-tau tangles in the brain - B vitamins.
If you are not taking in enough B6, folate or B12, which becomes harder to absorb as you get older, blood levels of a toxic amino acid called homocysteine rise. This increases the level of p-tau and inhibits the brain from clearing it. According to pharmacology professor David Smith, a member of APEG: “Homocysteine is not a diagnostic marker for dementia but it is a modifiable risk factor. Raised levels of homocysteine account for some 20% of dementia cases and homocysteine testing is relatively inexpensive and available.”
Smith, who was second in charge at Oxford University’s School of Medical Sciences, ran the VITACOG trial which found that high doses of B vitamins given to people with Mild Cognitive Impairment (MCI) and high homocysteine, not only slowed the rate of brain cell death by up to 73% but also arrested cognitive decline.
He, and his APEG colleagues, favour using a Cognitive Function Test, which is free, to identify those at risk then testing risk factors and biomarkers such as homocysteine to be included in the research funds being made available for testing blood biomarkers because this is one thing you can actually do something about. Other useful tests for risk factors include omega-3 and vitamin D levels, since low levels of these nutrients also increase risk; also HbA1c, the standard measure used to diagnose diabetes, since lower levels help protect the brain and high levels indicate those who need to reduce their intake of sugar and processed foods. These tests are corroborative rather than diagnostic but importantly identify prevention actions that people can take. This two-step paradigm of testing cognitive function early then further blood tests such as homocysteine, omega-3, vitamin D and HBA1c for glucose control that help guide diet and lifestyle prevention, is available right now. The charity foodforthebrain.org both test cognitive function for free and offer a home test kit that measures all these risk factors with a pin prick blood test.
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NOTES:
For further details about the Alzheimer’s Prevention Expert Group, which is a voluntary group of international dementia prevention experts, see foodforthebrain.org/apeg
The VITACOG trials, evidence for homocysteine as causal and lowering it with B vitamins as disease modifying and a consensus statement regarding this evidence, in the Journal of Alzheimer’s Disease, is here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5836397/
The validation of foodforthebrain.org’s Cognitive Function Test in the International Journal of Geriatric Psychiatry is here: https://onlinelibrary.wiley.com/doi/abs/10.1002/gps.3993
The evidence in relation to p-tau and homocysteine is here: https://foodforthebrain.org/the-p-tau-delusion/
Patrick Holford, founder of foodforthebrain.org and Chair of the Alzheimer’s Expert Group, and individual experts of the group, are available for interview.
Foodforthebrain.org is a not-for-profit independent registered charity.