Younger generations of older adults have lower proportions of dementia in the United States,  Europe and England, compared with older generations due to historical and societal factors impacting dementia risk, according to a new study.

A research team led by the University of Queensland in Brisbane, Australia, used data from three comparable surveys from the three regions to estimate how the prevalence of dementia changed across birth cohorts. Their findings were published in JAMA Network Open.

A cross-sectional study included 62,000 individuals aged more than 70 years from the three regions; it reportedly was the first study to use comparable datasets to compare dementia rates across countries. Specifically, the data showed that individuals from more recent birth cohorts had lower age-specific dementia prevalence rates in the United States (21% lower), Europe (39%) and England (28%). 

The data also showed that gender disparities in age-specific dementia prevalence have narrowed over the past decades, but “substantial” gender disparities persist. The investigators attributed those disparity differences to historical and societal factors that disproportionately have affected women’s overall well-being and access to resources over time, along with improvements in cardiovascular health, education, living conditions and access to healthcare.

“We often see statistics that show dementia prevalence rates are increasing — our study doesn’t refute that. As more people live longer, the total numbers of people diagnosed with dementia will grow,” Sabrina Lenzen, PhD, a co-author from the University of Queensland, said in a statement. “What we found was a statistically significant decline in people from more recent birth cohorts having dementia.”

The authors also said that if decreasing trends in dementia prevalence continue into the future, then the health and socioeconomic burden of dementia won’t likely increase in the future beyond dementia cases that typically come with an aging population. 

The generational decrease in dementia risk has important implications for healthcare planning, long-term care policies and workforce requirements in aging populations, they said.

“Our research is crucial for informing public health policies on expenditures and interventions aimed at preventing or managing dementia effectively across different generations, genders and regions, not just age groups,” the researchers concluded. “There is a strong need to continue to observe trends in dementia to prepare for future health planning.”