RECENT research into global dementia trends suggests that lifestyle changes, particularly in education and smoking cessation, may be contributing to a decline in dementia incidence in certain regions. Researchers conducted a comprehensive review of population-based cohort studies, examining how dementia prevalence and incidence have shifted over time.
The study utilised systematic reviews and primary studies, focusing on those that maintained consistent methodologies across multiple timepoints and used validated criteria for diagnosing dementia. The studies included in the analysis spanned various geographical locations and time periods, providing a broad perspective on the issue. Out of 1,925 records initially identified, 27 primary papers met the criteria for inclusion in the final analysis. These papers reported on changes in dementia prevalence and incidence across different regions, including Europe, the USA, Japan, and Nigeria.
The findings were conflicting: in Europe and the USA, a consistent decline in dementia incidence was noted, while Japan saw an increase in both prevalence and incidence, and Nigeria reported stable incidence rates.
The researchers also explored changes in dementia risk factors over time using population attributable fractions (PAFs). Notably, the PAFs for risk factors such as lower education levels and smoking generally declined, aligning with the observed decrease in dementia incidence in some regions. For instance, in the Framingham Heart Study conducted in Massachusetts from 1997 to 2013, the decline in these risk factors was linked to a reduction in dementia incidence. Conversely, PAFs for obesity, hypertension, and diabetes increased, reflecting the growing impact of these conditions on dementia risk.
The results highlight the potential of public health interventions, like improved education and smoking reduction, to mitigate dementia risk. However, the study also underscores the need for further research, particularly in low- and middle-income countries where dementia rates continue to rise. The authors advocate for more targeted studies in these regions to better understand and address the growing burden of dementia globally. This study adds to the growing body of evidence that lifestyle factors play a critical role in shaping dementia trends worldwide.
Laith Gergi, EMJ
Reference
Mukadam N et al. Changes in prevalence and incidence of dementia and risk factors for dementia: an analysis from cohort studies. Lancet Public Health. 2024;9(7):e443-60.
