Impact of Physical Activity Level on Memory in the Older Adult Population in the United States: A Cross-Sectional Study

Background: Physical activity (PA) is widely associated with improved cognitive function, including memory, in older adults. However, the extent to which this relationship varies across age groups and is influenced by other health and lifestyle factors remains unclear. This study examined the association between physical activity levels and self-reported memory problems in adults aged 50 to 85 years, using a nationally representative dataset to assess the relationship between physical activity levels and self-reported memory problems in adults aged 50 to 85 years, stratified by age groups. Methods: This exploratory cross-sectional study used the NHANES 2005-2006 dataset. The relationship between memory problems and activity levels was assessed across middle-aged (50–64 years) and elderly (65–85 years) groups. Multivariate analysis was adjusted for potential confounders, and age was tested as an effect modifier. Results: Among 3,277 participants, 22% were classified as less active. In unadjusted analyses, less active individuals had significantly higher odds of memory problems in both the middle-aged (OR = 2.15; 95% CI: 1.27–3.63; p = 0.004) and elderly groups (OR = 1.67; 95% CI: 1.01–2.75; p = 0.042). These associations were attenuated and no longer statistically significant after adjusting for confounders. Sleep disorders were significantly associated with memory problems in both age groups, while depression and lower education were significant only in the elderly. Conclusion: While physical activity shows a potential protective association with memory problems—particularly in middle-aged adults—this relationship appears to be influenced by other health and lifestyle factors. Age-specific interventions that address sleep quality, mental health, and education may be more effective in supporting cognitive health in older populations.