Decoding Blood

New biomarkers promise easier and earlier detection of Alzheimer's, but the results aren't always clear

- By Cassandra Willyard

THE FIRST HINTS that Gregory Nelson might be having cognitive troubles were subtle. So subtle, in fact, that his doctor assured him nothing was wrong. “Everyone who hits a certain age just misses words,” Nelson remembers him saying. When Nelson got home, he regretted not pushing harder for a referral. His entire family had noticed changes. Nelson, who is 70, scheduled another appointment and convinced his physician to send him to a neuropsychologist.

Nelson's greatest fear was that he was in the beginning stages of Alzheimer’s—his father, though never formally assessed, had probably died of the disease. But Nelson didn’t get a diagnosis, at least not right away. He waited months to be seen by the neuropsychologist his physician referred him to. That specialist performed a cognitive assessment, which indicated mild cognitive impairment, but the doctors couldn’t yet tell him the cause. The neurologists in his area were completely booked, so there was another lengthy wait between his primary-care visit and his diagnosis of Alzheimer’s.

The delay gave Nelson ample time to prepare for the worst, but it also created a lot of uncertainty and anxiety.