clinical focus
Blood test
Could blood tests to detect Alzheimer ’ s be on the horizon ?
By Elise Hartevelt
Ground-breaking new research has presented new hope in catching early signs of Alzheimer ’ s by gauging a specific biomarker in the blood that increases the odds of developing the disease by a third .
A Macquarie University and CSIRO study revealed that people with elevated metabolite 3-HAA were 35 per cent more likely to progress to Alzheimer ’ s than those with normal levels .
It ’ s one of the most comprehensive longitudinal studies worldwide , where the researchers followed nearly 300 older people for 12 years over intervals of 18 months .
“ We need more research , but there are so many exciting possibilities here ,” said co-researcher Dr David Lovejoy .
“ This particular metabolite predicts your risk of mild cognitive impairment or dementia that occurs several years before you are diagnosed .
“ We hope to progress to a simpler blood test , where , if someone has a positive test , it would be a wake-up call to modify your lifestyle .”
Dementia is currently the second leading cause of death in Australia , and effective
treatment and early detection tools remain under development .
Alzheimer ’ s pathology is characterised by a build-up of amyloid plaques and tau proteins in the brain , and the neurological system ’ s inflammation is considered a key culprit .
“ It ’ s becoming clearer that chronic inflammation plays a significant role in Alzheimer ’ s disease and dementia by increasing amyloid toxicity ,” Lovejoy said .
“ We found that inflammation of a particular pathway could reliably predict who would eventually develop dementia .”
The kynurenine pathway ( KP ) produces metabolites involved in immune regulation and protecting the brain , spinal cord , and nerves .
When this pathway is not functioning well , it produces higher levels of neurotoxic metabolites , such as 3-HAA , that can kill neurons .
“ In the past , 3-HAA has been observed to drop after a diagnosis of dementia , but nobody has ever looked at the lead-up of the disease ,” Lovejoy said .
“ We were surprised to see increased 3-HAA levels strongly predicting risk of developing mild cognitive dysfunction that leads to a diagnosis of dementia .”
Although 3-HAA has a protective , antioxidant effect on the brain , it ’ s toxic to T-cells , which play a crucial role in clearing amyloid plaques in the brain .
Lovejoy said there ’ s still debate in the scientific community whether the
“
There are so many exciting possibilities here .
increase in amyloid plaques is a mediator of neuronal damage or just a standby product .
“ There ’ s still some doubt , but there is some suggestion that 3-HAA has a negative effect on the immune system , specifically on T-cells .
“ Or what might be happening is that for people who are going to progress to Alzheimer ’ s , the KP kicks into action and produces 3-HAA , which has antioxidant properties .
“ So , it might also be a mechanism showing the body ’ s trying to clean up the problem .”
While the research is still in its infancy , Lovejoy said there ’ s a convincing argument that future rapid blood tests for 3-HAA will emerge on the market .
“ In theory , if you found your levels were high , you could get a brain scan to determine whether there ’ s a build-up of amyloid plaques and begin taking preventative measures ,” he said . “ But we don ’ t know yet whether the increased levels of 3-HAA leading up to dementia can be reversed .” Lovejoy emphasised that pursuing a healthy lifestyle offers a surplus of benefits in preventing inflammation in the body and preventing chronic disease in later life .
Lifestyle changes such as following a Mediterranean diet , cutting back on alcohol intake , and daily exercising can also help stave off the onset of Alzheimer ’ s , he said . ■
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