A study has found that a women'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.