A short report published last week in the Journal of Alzheimer’s Disease claims that a simple saliva test can determine whether or not a person is at risk for developing the incurable neurodegenerative disease by measuring the amount of plaque-forming beta-amyloid protein their body produces. If the levels are high, the authors propose that lifestyle changes, such as taking a daily regimen of anti-inflammatory drugs, can be adopted early in order to postpone the onset of symptoms and reduce disease severity.
Considering that the current methods predicting Alzheimer’s disease (AD) are either unreliable or still experimental, this sounds like great news. On closer inspection, however, it appears that the team may have jumped the gun.
In their much-buzzed-about three-page paper and its accompanying press release, Drs Edith and Patrick McGeer of Aurin Biotech state that in a 2016 investigation they “developed a simple saliva test that can diagnose AD, as well as predict its future onset” by quantifying levels of the A?42 protein in the body. A?42 is a misproduced protein fragment that accumulates – beginning years to decades before neurological symptoms arise – in the extracellular space of AD patients' brains in clusters called fibrils. These fibrils are toxic to brain tissue.
The initial evaluation of this system proved to be quite promising: AD subjects consistently showed saliva A?42 levels that were two-fold higher than controls, as did subjects known to be at a high risk for AD development thanks to family history.
The problem? Their A?42 test was only evaluated in 37 people – a pretty small sample size for such bold claims.
“While a simple saliva test for Alzheimer’s sounds appealing, this is very early stage research that needs much more investigation before it could be considered clinically,” Dr Carol Routledge, director of research at Alzheimer’s Research UK, said to the Science Media Centre in response to the new report.
When addressing how newly-identified AD patients can “prevent disease development through self treatment”, the team state that more than 17 studies – including one of their own – have confirmed that a regimen of over-the-counter anti-inflammatory drugs (NSAIDs), such as ibuprofen, taken 10 to 15 years before the typical age of onset (around 65) can spare A?42 over-producers from their impending neural decline. In reality, all that these studies demonstrated was a correlation between NSAIDs and less severe AD symptoms.
According to Professor Tara Spires-Jones, lead of the UK Dementia Research Institute Programme, the handful of placebo-controlled clinical trials that directly evaluated NSAIDs in Alzheimer’s patients all failed to show any benefit, though she concedes that “it remains possible that using this type of drug many years before the disease starts could be preventative – but more work is needed to be sure.”
“The long-term use of certain anti-inflammatories, like ibuprofen, can increase your risk of other health problems and there is currently insufficient evidence that they are effective or safe to use to prevent Alzheimer’s disease,” Dr Routledge added.
