Differential Effects of Lifestyle Indicators on Cognitive Functioning Across Healthy, Dementia, Parkinson's Disease, and Stroke Groups.

Background/Objectives: As life expectancy increases, chronic diseases have become more prevalent, often leading to poorer health in later years. Maintaining cognitive functioning is therefore essential for preserving independence in older adulthood. Within the framework of cognitive enrichment, research highlights the protective role of healthy lifestyles and engagement in social and intellectual activities on cognitive functioning. This study aimed to provide evidence of the moderator effect of diagnosis group (including healthy condition, dementia, Parkinson's, and stroke) on a predictive model of cognitive function. Methods: Data employed in this study came from the 9th wave of the Survey of Health, Ageing and Retirement in Europe (SHARE) project, including 17,105 individuals aged 50 years and older from 27 European countries. Cognitive functioning was assessed through numeracy, temporal orientation, verbal fluency, and memory. Physical inactivity, social participation, intellectual activities, age, gender, and education were included as predictors. A measurement invariance routine across diagnostic groups was tested. Results: The model demonstrated excellent fit in the general sample and partial invariance across groups. Physical inactivity was negatively associated with numeracy in all groups, with stronger effects in clinical populations, particularly stroke and dementia. Intellectual activities were positively associated with numeracy across groups, with the largest effects observed in dementia. Temporal orientation, physical inactivity and intellectual activities showed significant associations mainly in clinical groups, whereas age demonstrated a consistent negative effect across all groups. Conclusions: Lifestyle factors show differential associations with cognitive domains depending on diagnostic condition. These findings support the heterogeneity of cognitive aging and highlight the importance of tailored, person-centered intervention strategies.