Objective:To determine changes in the incidence of dementia between 1988 and 2015.Methods:This analysis was performed in aggregated data from individuals >65 years in seven population-based cohort studies in the United States and Europe from the Alzheimer Cohort Consortium. First, we calculated age- and sex-specific incidence rates for all-cause dementia, and then defined non-overlapping 5-year epochs within each study to determine trends in incidence. Estimates of change per 10-year interval were pooled and results are presented combined and stratified by sex.Results:Of 49,202 individuals, 4,253 (8.6%) developed dementia. The incidence rate of dementia increased with age, similarly for women and men, ranging from about 4 per 1,000 person years in individuals aged 65-69 years, to 65 per 1,000 person years for those aged 85-89 years. The incidence rate of dementia declined by 13% per calendar decade (95% CI: 7%-19%), consistently across studies, and somewhat more pronouncedly in men than in women (24% [95% CI 14%-32%] versus 8% [0%-15%]).Conclusion:The incidence rate of dementia in Europe and North America has declined by 13% per decade over the past 25 years, consistently across studies. Incidence is similar for men and women, although declines were somewhat more profound in men. These observations call for sustained efforts to finding the causes for this decline, as well as determining their validity in geographically and ethnically diverse populations.

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Key Points Question Is light-intensity physical activity associated with brain volume? Findings In this community-based cohort study of 2354 participants, each additional hour spent in light-intensity physical activity was associated with larger brain volume, equivalent to approximately 1.1 years less brain aging. Achieving 10 000 or more steps per day was associated with higher brain volume compared with those achieving fewer than 5000 steps per day. Meaning Incremental physical activity, even at a more practical light intensity, may be involved in the maintenance of brain structures into older age.

Background Non‐alcoholic fatty liver disease (NAFLD) is common and has been recently related to brain health. We aimed to assess the relationships of NAFLD and its severity, using the NAFLD fibrosis score (NFS), with cognitive performance. Methods Framingham study Offspring and 3rd generation participants were included if they attended exams 9 (2002‐2008) and 2 (2008‐2011), respectively, were free of dementia and stroke, and did not have excessive alcohol intake. Between 2008 and 2011, participants underwent Multi‐detector computed tomography scans of the abdomen to determine NAFLD diagnosis and the NFS was used to categorize the severity of fibrosis. Cross‐sectional relationships of NAFLD and the NFS with cognitive testing of memory, abstract reasoning, visual perception, attention and executive function were assessed, while adjusting for multiple cardiometabolic variables including visceral adipose tissue, diabetes and insulin resistance. Results Of the 1287 participants (mean age = 61±12 years, 48% men), 378 (29%) had NAFLD. The presence of NAFLD was not associated with cognitive function. However, among those with NAFLD (mean age = 61±12 years; 58% men), high compared to low risk of advanced fibrosis was associated with poorer performance on similarities (β = −2.22 ± 0.83; P = 0.009) and trail‐making B minus A (β = −0.11 ± 0.05; P = 0.028), independently of potential confounders. Conclusions Participants with high risk of advanced fibrosis may have poorer cognitive function compared to those with low risk, particularly in executive function and abstract reasoning. Future findings are necessary to evaluate the value of the NFS as a biomarker that predicts cognitive impairment and dementia and to explore the role of hepatic fibrosis in brain health.