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Member Research & Reports

Member Research & Reports

Michigan Study Finds Puzzling Trends in Dementia Rates

A new large-scale study from SPH professor Dr. Kenneth Langa, finds that dementia rates among the elderly have declined from 11.6 percent in 2000 to 8.8 percent in 2012 based on survey results from this period. This means that about 1.5 million adults, who would have had dementia if the rates had remained static, have avoided the disease. Other studies have also shown this decreasing trend but none have been as diverse or large as this recently published research.

[Photo: Dr. Kenneth Langa]

What is puzzling about these results is the fact that known risk factors for dementia such as obesity and diabetes are increasing among the older population, making the dropping rates of dementia seem counterintuitive.

Dr. Langa notes that the surveyed population in 2012 had overall higher educational achievement than the 2000 group, indicating that this might be a factor in avoiding dementia. Previous research has shown that the neural pathways formed as we continue our education later in life can have a preserving effect on brain function, potentially staving off symptoms of dementia. Another factor that could be suppressing dementia could be better attention to nutrition and better management of chronic conditions (even if their rates are actually increasing).

Even with this insight, the future is uncertain as far as whether dementia rates will continue to decline or creep back up. Populations that will be entering old age in the coming years have spent more of their lives with risk-increasing conditions like obesity and diabetes than the 2012 study cohort had, but with increasing education, decreased smoking, and improvements in care procedures, predicting dementia rates in this group difficult. Furthermore, even if rates continue to decline, the absolute numbers of people presenting with dementia may increase as the baby boomers enter old age with the generations following them only getting larger. This means that the burden on the local treatment level may not reflect any overall decline in dementia rates at the population level.

What this study indicates over all is that the risk factors and protective factors leading to dementia are complex, and more research is necessary to elucidate the reasons behind the recent decline and how we might help this trend continue into the future.

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