A simple blood test may soon be available to diagnose patients with Alzheimer’s Disease (AD) and frontotemporal dementia (FTD), says a report in Nature Medicine.
Blood sample proteins were analysed from 362 people aged 58-70 years, who had a diagnosis of AD (n=56), FTD (n=190), mild cognitive symptoms (n=47) or were healthy controls (n=69).
The results showed that pTau181 was 3.5-times higher in participants with AD than in both healthy controls and differentiated AD, from clinically-diagnosed (area under the curve [AUC] 0.894) and autopsy-confirmed frontotemporal lobar degeneration (AUC 0.878).
Plasma pTau181 identified individuals who were amyloid β-PET-positive, regardless of clinical diagnosis. This also correlated with cortical tau protein deposition measured by 18F-flortaucipir PET.
After two years follow up, researchers found that higher levels of pTau181 predicted a more rapid cognitive decline. Neurofilament light chain (NfL) protein that normally provides neuronal structure, was also found to be elevated in the blood of FTD patients compared to other groups.
Blood amyloid levels were less accurate than pTau181 at indicating dementia.
This blood-based test is as accurate as the currently approved cerebrospinal fluid or amyloid β PET but would be less invasive and less expensive, the authors say.