A blood test that helps diagnose Alzheimer’s might also forecast if healthy older adults will develop symptoms. A new study links high levels of so-called p-tau217 to a high risk of cognitive impairment in five or 10 years. Scientists stressed it’s too soon to get tested — instead healthy people should try proven risk-reducing strategies like eating well, getting enough sleep and exercising. But drugs that might prevent or delay Alzheimer’s are being developed and the blood test could be important if they pan out. The findings were published in JAMA on Wednesday and presented at the Alzheimer’s Association International Conference.