Six years ago, at age 49, Julie Gregory paid an online service to sequence her genes, hoping to turn up clues about her poor circulation, blood-sugar swings and general ill health. Instead she learned she had a time bomb hidden in her DNA: two copies of a gene variant, ApoE4, that is strongly linked to Alzheimer's. Most Americans with this genotype go on to develop late-onset dementia.
"Alzheimer's was the furthest thing from my mind," Ms. Gregory told me. "I never thought I was at risk. When I saw my results, I was terrified."
When Ms. Gregory consulted with a neurologist about how to delay the onset of illness, he had four words for her: "Good luck with that." After all, no drug had proven effective in reversing Alzheimer's disease. And preventive measures like diet and exercise, the neurologist told her, would do no good.
Ms. Gregory is not the sort of person who pops into your mind when you think of Alzheimer's — youngish, healthy and sharp-minded. But she represents a type of sufferer we are likely to encounter more and more: those grappling with the looming threat of the disease rather than the disease itself.