As millions of Baby Boomers reach old age, cases of dementia were expected to spike. Last summer a bold prediction of 28 million cases of Alzheimer's by 2050 was made at a major conference.
But now a Boston University team contends that the rate of dementia cases is actually decreasing - potentially through healthier living.
"Currently there are no effective treatments to prevent or cure dementia; however, our study offers hope that some of the dementia cases might be preventable - or at least delayed - through primary or secondary prevention," said Sudha Seshadri, a neurologist at the BU School of Medicine. "Effective prevention could diminish in some measure the projected explosions in the number of persons affected with the disease in the next few decades."
The rates of dementia per 100 people went down during the successive decades from the late 1970s through the beginning of the millennium, according to the study, published in the latest New England Journal of Medicine.
The late 1970s to early 1980s dementia rate of 3.6 per 100 people decreased to 2.8 per 100 by the late 1980s, 2.2 per 100 for the 1990s, and down to 2.0 per 100 people into the second decade of the 21st century. The data came from more than 5,000 people in the massive Framingham Heart Study in Massachusetts.
However, caveats exist - the population was disproportionately of European heritage, and the decline in the dementia rates was only found in people with a high school education diploma or better, according to the authors. (A new study by University of California San Francisco researchers contends major disparities between ethnic groups exist in dementia rates).
Overall cardiovascular health may be responsible for more than offsetting the increase in life expectancy, they said. Smoking, blood pressure, diabetes and other health factors have generally been improved upon - leading to the lower rates of dementia, the guessed.
"It is very likely that primary and secondary prevention and better management of cardiovascular disease and stroke, and their risk factors, might offer new opportunities to slow down the currently projected burden of dementia for the coming years," said Carole Dufouil, research director of Inserm in Bordeaux, France.
But the overall number of people with Alzheimer's will still continue to grow, since the Baby Boomers are continuing to age.
Last year's Alzheimer's Association meeting produced the 28-million estimate by the year 2050. However, another discouraging sign was the relative dearth of new drugs and therapies - producing most notably the re-proposal of solanezumab, a drug that had previously proven ineffective at reversing progress of the disease, as a slowing agent at the earliest stage of the disease.
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