Stop the press! Is this good news about Alzheimer's Disease? It depends on how you look at it.
A recent perspective article*, published in the New England Journal of Medicine, cites several studies supporting the notion that the risk of having Alzheimer's disease is declining. The article notes that the probability of a person of a given age, having any form of dementia today, is lower than it was a few decades ago. That sounds positive.
Despite the tempting headline of "Declining Risk", such a trend is most likely driven by overall improvements in population health. Today's seniors are unquestionably wealthier and better educated than those of the past, they smoke less, have fewer strokes, have better managed cholesterol, and have lower blood pressure. All of those factors affect risk of Alzheimer's disease and other causes of dementia.
Also, while risk at a given age may be declining, the number of people reaching old age (and even very old age) is sharply climbing. Prevalence at a given age may be lower, but incidence at older ages is clearly rising.
There is no reason to believe that the risk of Alzheimer's disease is magically declining. There is much hope, however, that awareness about risk factors and the importance of managing them, is helping us to forestall the ravages of dementing illnesses, and buying time for the nation's R&D efforts to find better treatments.
So keep exercising, eating right, using your brains, and managing your chronic conditions. For now, that is your best strategy for keeping your brain healthy for the longest time.
* n engl j med, 369;24, nejm.org, december 12, 2013