The outcome of the study revealed other interesting associations, too. A blood test may predict dementia risk in women as early as 25 years in advance, according to findings from a recent study published in the Journal of the American Medical Association on Wednesday. Researchers evaluated whether there were associations between the levels of the protein plasma phosphorylated tau 217 (p-tau217) found in someone’s blood and their risk for mild cognitive impairment, or MCI, and dementia. P-tau217