JAMA, published by the American Medical Association, announced on November 21, 2016, the results of its most recent study which indicate dementia prevalence declined significantly, from 11.6% in 2000 to 8.8% in 2012. The national study of more than 21,000 diverse senior citizens can be found here. JAMA’s findings are significant, if not somewhat surprising since scientists continue to report that obesity, diabetes, and other diseases thought to increase the risk of dementia are all on the rise.

An estimated 4 to 5 million seniors in the U.S. live with dementia, a broad term that describes a decline in memory and cognitive function. Those with a dementia diagnosis are also at increased risk for Alzheimer’s disease, Parkinson’s disease and dementia with Lewy bodies. Experts aren’t sure what causes dementia, but scientists have found that cardiovascular disease, diabetes, and obesity all raise a person’s risk of cognitive decline.

The JAMA study is the largest to date finding that dementia rates are decreasing, but it isn’t the first. There have been several smaller studies, with less diverse groups, which have also indicated that dementia is on the decline.But are such findings a fluke or will the rate of dementia continue to decline? Time will only tell. In the meantime, while current studies show dementia trends moving in a positive direction, clearly more research needs to be conducted to understand why dementia develops in some people and how we can avoid it.