Investigating the individual and joint effects of socioeconomic status and lifestyle factors on mild cognitive impairment in older Italians living independently in the community: results from the NutBrain study

Objectives: Despite extensive research, a clear understanding of the role of the interaction between lifestyle and socioeconomic status (SES) on cognitive health is still lacking. We investigated the joint association of socioeconomic factors in early to midlife and lifestyle in later life and Mild Cognitive Impairment (MCI). Design: Observational cross-sectional study. Setting: NutBrain study in northern Italy. Participants: 773 community-dwelling adults aged 65 years and older (73.2 ± 6.0 SD, 58.6% females) participating in the NutBrain study (2019-2023). Measurements: Three SES indicators (home ownership, educational level, occupation) and five lifestyle factors (adherence to Mediterranean diet, physical activity, smoking habits, social network, leisure activities) were selected. Each factor was scored and summed to calculate SES and healthy lifestyle scores; their joint effect was also examined. The association with MCI was assessed by logistic regression controlling for potential confounders. Sex-stratified analysis was performed. Results: In total, 24% of the subjects had MCI. The multivariable logistic model showed that a high SES and a high lifestyle score were associated with 81.8% (OR0.182; 95%CI 0.095-0.351), and 44.1% (OR0.559; 95%CI 0.323-0.968) lower odds of having MCI, respectively. When examining the joint effect of SES and lifestyle factors, the cognitive benefits of a healthy lifestyle were most pronounced in participants with low SES. A healthier lifestyle score was found to be significantly associated with lower odds of MCI, only in females. Conclusions: According to our findings, SES was positively associated with preserved cognitive function, highlighting the importance of active lifestyles in reducing socioeconomic health inequalities, particularly among those with a relatively low SES. Trial registration: Trial registration number NCT04461951, date of registration July 7, 2020 (retrospectively registered, ClinicalTrials.gov).