Exploring the trends and lifestyle influences on dementia: a global perspective

Changes in the occurrence and new cases of dementia and its risk factors
Dementia, a condition affecting memory and cognitive function, has been a growing concern globally. Some studies suggest that the number of people with dementia is decreasing over time, but the results aren’t always consistent. This review and meta-analysis aimed to examine this further and investigate how lifestyle factors and their changes over time may contribute to changes in the occurrence and incidence of new dementia cases worldwide. To achieve this, various population-based studies that tracked dementia over time were scrutinized. Out of 1925 studies, five major reviews were identified, resulting in 27 key studies. Four of these were the NEAR-based studies: the Swedish National study on Aging and Care – Kungsholmen (SNAC-K) and Nordanstig (SNAC-N), the Kungsholmen Project (KP), and the Gothenburg H70 Birth Cohort Study (H70).

Photo: Cecilia Öhlund

Improved education and reduced smoking may have led to a decrease in new dementia cases
About half of the included 27 studies showed changes in the prevalence of dementia, while the others examined the incidence of dementia (new cases). In Europe (5 studies) and the USA (5 studies), new cases of dementia seem to be decreasing. However, in one study from Japan, both the prevalence and incidence are rising, and in Nigeria, the incidence remains stable. Related to lifestyle factors, over time, fewer people are smoking, and more are getting educated, which might be linked to the decrease in dementia cases. However, issues like obesity, hypertension, and diabetes are becoming more common. The findings suggest that improving education and reducing smoking, through public policies, could be related to a reduction in dementia occurrence, and thus a decline in the rates of new cases of dementia. However, more research is needed, especially in low- and middle-income countries where dementia is becoming more common.

Publication
Mukadam, N., Wolters, F. J., Walsh, S., Wallace, L., Brayne, C., Matthews, F. E., Sacuiu, S., Skoog, I., Seshadri, S., Beiser, A., Ghosh, S., & Livingston, G. Changes in prevalence and incidence of dementia and risk factors for dementia: an analysis from cohort studies. The Lancet Public Health. 2024;9(7), e443–e460. https://doi.org/10.1016/s2468-2667(24)00120-8.