A new Swedish study published in the journal Neurology shows that the risk of developing dementia may have declined over the past 20 years, in direct contrast to what many previously assumed. The result is based on data from the SNAC-K, an ongoing study on aging and health that started in 1987.
"We know that cardiovascular disease is an important risk factor for dementia. The suggested decrease in dementia risk coincides with the general reduction in cardiovascular disease over recent decades," says Associate Professor Chengxuan Qiu of the Aging Research Center (ARC), established by Karolinska Institutet and Stockholm University. "Health check-ups and cardiovascular disease prevention have improved significantly in Sweden, and we now see results of this improvement reflected in the risk of developing dementia."
Dementia is a constellation of symptoms characterized by impaired memory and other mental functions. After age 75, dementia is commonly due to multiple causes, mainly Alzheimer's disease and vascular dementia. In the current study, more than 3000 persons 75 years and older living in the central Stockholm neighborhood of Kungsholmen participated. Of the participants, 523 were diagnosed with some form of dementia. The key members of the research group have been essentially the same since 1987, including the neurologist responsible for the clinical diagnoses of dementia. All study participants were assessed by a nurse, a physician, and a psychologist.
The result shows the prevalence of dementia was stable in both men and women across all age groups after age 75 during the entire study period (1987-1989 and 2001-2004), despite the fact that the survival of persons with dementia increased since the end of the 1980s. This means that the overall risk of developing dementia must have declined during the period, possibly thanks to prevention and better treatment of cardiovascular disease.
"The reduction of dementia risk is a positive phenomenon, but it is important to remember that the number of people with dementia will continue to rise along with the increase in life expectancy and absolute numbers of people over age 75," says Professor Laura Fratiglioni, Director of the Aging Research Center. "This means that the societal burden of dementia and the need for medical and social services will continue to increase. Today there's no way to cure patients who have dementia. Instead we must continue to improve health care and prevention in this area."
The study was funded by the Swedish Council for Working Life and Social Research (FAS ), the Swedish Ministry of Health and Social Affairs, the Swedish Research Council, and Swedish Brain Power.
- C. Qiu, E. von Strauss, L. Backman, B. Winblad, L. Fratiglioni. Twenty-year changes in dementia occurrence suggest decreasing incidence in central Stockholm, Sweden. Neurology, 2013; DOI: 10.1212/WNL.0b013e318292a2f9
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