Global dementia...

“There is evidence of sex differences in the biological mechanisms that underlie dementia. It’s been suggested that Alzheimer’s disease may spread differently in the brains of women than in men, and several genetic risk factors seem related to the disease risk by sex.”

According to co-author Professor Theo Vos from IHME, University of Washington, USA, “Low- and middle-income countries in particular should implement national policies now that can mitigate dementia risk factors for the future, such as prioritising education and healthy lifestyles. Ensuring that structural inequalities in access to health and social care services can be addressed and that services can additionally be adapted to the unprecedented needs of an increasing older population with complex care needs will require considerable planning at both local and national levels.”

The authors acknowledge that their analysis was limited by a lack of high-quality data in several parts of the world, including sub-Saharan Africa, eastern Europe, and Central America, and by studies using different methodologies and definitions of dementia. They also note that they were unable to consider all 12 risk factors from the 2020 Lancet Commission report because they were limited to risk factors included in the GBD study and only included risk factors with strong evidence of association. However, including additional risk factors would not have necessarily led to a change in the forecasted prevalence, unless changes in exposure to a given risk factor were expected as well. Finally, they note that the study examined the overall prevalence of dementia, and it is possible that clinical subtypes, such as vascular dementia, may have different relationships with risk factors, which could affect the results.

Writing in a linked Comment, Dr Michaël Schwarzinger and Dr Carole Dufouil, Bordeaux University Hospital in France (who were not involved in the study) say, “In our opinion, the authors’ efforts to build on GBD 2019 are still oversimplifying the underlying mechanisms that cause dementia…[they] provide apocalyptic projections that do not factor in advisable changes in lifestyle over the lifetime.