New Delhi, March 11 A study has found that a woman's risk of developing dementia may be predicted 25 years before symptoms begin through a test of a blood-based biomarker called 'phosphorylated tau 217' – a protein linked to the brain changes seen in Alzheimer's disease.
Higher levels of phosphorylated tau 217, or p-tau217, were strongly associated with future mild cognitive impairment and dementia – of which Alzheimer's disease is the most common form – among older women who were cognitively healthy at the study's start.
"Our study suggests that we may be able to identify women at elevated risk for dementia decades before symptoms emerge," said Aladdin H. Shadyab, first author and associate professor of public health and medicine at the University of California San Diego.
"That kind of long lead time opens the door to earlier prevention strategies and more targeted monitoring, rather than waiting until memory problems are already affecting daily life," Shadyab said.
The study, published in The Journal of the American Medical Association (JAMA) Network Open, analysed data from 2,766 participants in the Women's Health Initiative Memory Study, a US national study that enrolled women aged 65 to 79 in the late 1990s and followed them for up to 25 years.
Women who developed memory or thinking problems, including dementia, were identified during follow-up.
Higher levels of p-tau217 in blood at the start of the study were related with a higher chance of developing dementia later in life, with increasing levels of the biomarker related with increasing dementia risk.
Higher p-tau217 levels were also more strongly associated with poorer cognitive outcomes among women aged 70 and above, compared to those younger, and among those with the APOE e4 genetic risk factor for Alzheimer's disease.
The study also found that p-tau217 was more predictive of dementia among women who were randomly assigned estrogen plus progestin hormone therapy versus placebo.
"In this cohort study of cognitively unimpaired older women, p-tau217 was associated with incident MCI (mild cognitive impairment) or dementia up to 25 years later. These findings suggest that age, race, APOE e4, and HT (hormone therapy) use should be considered when examining associations of p-tau217 with cognitive outcomes," the authors wrote.
"Blood-based biomarkers like p-tau217 are especially promising because they are far less invasive and potentially more accessible than brain imaging or spinal fluid tests," said Linda K. McEvoy, a senior investigator at Kaiser Permanente Washington Health Research Institute, US.
"This is important for accelerating research into the factors that affect risk of dementia and for evaluating strategies that may reduce risk," McEvoy said.