NEJM: ‘Cautious optimism should not become complacency’ in fight against dementia

Despite recent research and positive historical trends signaling an overall decline in instances of dementia in certain populations, persistence is needed to ensure that progress against the disease does not reverse course, according to a historical perspective published online Feb. 11 by the New England Journal of Medicine.

Citing results of a study published in the same issue by Satizabal, et al., that found a 20 percent reduction in dementia each decade over a 30-year span, authors David Jones, MD, PhD, of Harvard University, and Jeremy Greene, MD, PhD, of Johns Hopkins University, attempted to put the disease’s decline in perspective through historical context.

“Can we now conclude that the tide has turned in the dementia epidemic?” they wrote. “The potential decline of dementia, seen in light of the rise and fall of other major diseases, raises an even more tantalizing prospect: Can we control our burden of disease?”

To answer that question, Jones and Greene compared the dementia data to the history of coronary artery disease (CAD) research, which in the 1960s revealed a reduced prevalence of the disease despite widely accepted beliefs that instances of CAD would increase along with average lifespans.

“It was only in 1974 that researchers began taking the prospect of [CAD] decline seriously,” the authors wrote. “This recognition triggered debate over the contribution of medical and public health interventions, in hopes that knowledge of the causes of decline would guide policies and resource allocation and ensure continuation of these health benefits.”

But confirming the decline of any given disease is extremely complex, said Jones and Greene, who offered three lessons learned from the history of CAD for those trumpeting dementia’s decline.

“First, it can be extremely difficult to produce timely and convincing data about the trajectories of chronic diseases,” they wrote. “Second, since trajectories of chronic-disease incidence reflect complex interactions of many causal factors, it will almost always be uncertain whether decreases will continue or reverse. … Third, these ambiguities open up a battleground for conflicting interpretations by interested parties.”

Despite the challenges, Jones and Greene believe the findings by Satizabal and colleagues merit further research into pinpointing potential causes of the declining prevalence of dementia, and they remain hopeful that continued progress can help dramatically reduce the burden of the disease on modern society.

“With this latest contribution, optimism about dementia is more justified than ever before,” the authors concluded. “But cautious optimism should not become complacency. If we can elucidate the changes that have contributed to these improvements, perhaps we can extend them.”