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Researchers have warned that social media may be misleading healthy people into taking Alzheimer’s blood tests, causing severe anxiety over biological markers that may never actually cause dementia.
Blood-based biomarker tests, such as p-tau217 and p-tau181, detect biological signs of changes in the brain associated with Alzheimer’s disease, which is a progressive brain disorder and the leading cause of dementia.
The testing looks for abnormal proteins, which can be a sign of brain changes due to Alzheimer’s. Much hope has been placed in the tests because they are often quicker and more accessible compared with other methods to diagnose Alzheimer’s, such as brain imaging or lumbar punctures.
There is global consensus among peak neurological bodies, including the Alzheimer’s Association, that such tests should never be used for healthy people with no symptoms.
The tests should not be used on their own to diagnose Alzheimer’s and need to be combined with other medical assessments, according to clinicians and peak bodies. Because they detect signs of Alzheimer’s early, a person can test positive for the biological markers of disease – but they may not ever go on to develop the clinical symptoms of dementia.
Dr Jenna Smith from the University of Sydney’s school of public health said this has not stopped laboratories, influencers and doctors around the world from promoting the tests on social media.
She and her colleagues analysed 188 posts mentioning Alzheimer’s or dementia and blood tests from accounts with a combined global audience of more than 114 million followers across Facebook, Instagram and TikTok.
Smith said about 10% of the posts were doctors from claiming the test could be useful for asymptomatic screening and that most of these were from the US.
“Some of these doctors had pretty clear financial interests,” Smith said. “But it isn’t all doom and gloom. Some doctors were sharing information about these new blood tests with longer videos and covered the nuance that this issue deserves. Some also specifically drew attention to the limitations and potential harms.”
The findings were published in the Journal of the American Geriatrics Society on Tuesday.
The researchers found more than one-third of posts promoted the tests for people without symptoms, and that accounts with explicit financial interests were more than three times as likely to do so.
“The main potential harms are being unnecessarily diagnosed and not having a clear pathway for what to do next,” Smith said.
“Healthy people who undergo these tests could be diagnosed with Alzheimer’s disease but not go on to develop dementia. It is also not clear what to do next after testing positive.
“Research on treatments has been done in people with mild cognitive impairment or dementia, so we don’t know if they work for healthy people who test positive.
“There are also possible side effects and costs of treatment to consider, and the psychological impact and burden of diagnosis on individuals, their families and communities, and insurance implications.”
The president of the Australian and New Zealand Society for Geriatric Medicine, Prof Susan Kurrle, said the tests should only ever be ordered by doctors in specific circumstances.
“From the evidence, it is clear that to ensure an accurate result there needs to be a high pre-test probability that the person has early Alzheimer’s disease before the test is performed,” she said.
“It is most definitely not a screening test. Any unnecessary and expensive tests are bad news.”
When ordered through a doctor in Australia, the tests cost up to $AU400 and are not covered by Medicare.
Patients seeking out the tests online are being charged $600, before undergoing an eligibility assessment. Another provider offers the test for $365 with no mention of pre-test screening.
Kurrle said there is a risk that a false positive result may lead people to believe that they are inevitably going to develop dementia.
“Alternatively a negative result may lead a person to think that they are not at risk and to not address the modifiable risk factors such as low levels of exercise, and the various vascular risk factors including LDL cholesterol, or hearing or vision loss,” she said.
