In Europe and the U.S., proportionately fewer people are developing dementia now than in the past. Is this driven by less-prevalent Alzheimer’s disease pathology? No, say researchers led by Francine Grodstein at Rush University Medical Center in Chicago. In the February 20 JAMA Neurology, they reported that among 1,550 older Americans born over a 25-year period, all had similar amounts of amyloid plaques at death, which came at an average of 90 years.
- Prevalence of amyloid plaques has remained steady over the past 25 years.
- Neurofibrillary tangle burden may be on the rise.
- Atherosclerosis in the brain is becoming less common.
If less pathology does not explain falling dementia incidence, then what does? People born in the 1920s had healthier blood vessels in their brains when they died than did those born in the 1900s, the authors found. They think better cardiovascular health among people born in more recent decades may make them more resilient to AD pathology.
“This research reinforces the importance of population-based efforts to improve vascular health and suggests that we may already be seeing dementia prevention in action,” wrote Jonathan Schott of University College London (comment below). Chengxuan Qiu, Karolinska Institutet, Sweden, called this an important study. “[It] could help explain the observation of declining incidence of dementia in Western societies,” Qiu told Alzforum. “Neurodegenerative pathology seems to be determined by age, but vascular pathology could be modified by reducing risk factors for cardiovascular disease,” he added.
Dementia incidence has steadily fallen by 20 to 25 percent over the past three decades in the U.S., U.K., Sweden, and the Netherlands (Jul 2013 conference news; Apr 2016 news; Sep 2017 news; Tom et al., 2020). Researchers suspect that this drop was due to better overall health—especially improvements in cardiovascular health—and higher levels of education (May 2013 news; Feb 2016 news). Might these factors stave off amyloid plaques and neurofibrillary tangles?