Interactions between APOE genotype and lifestyle factors on cognitive functioning: Results of the health study of the Leipzig research center for civilization diseases (LIFE)

Background: The APOE gene is associated with a high risk for cognitive decline and the development of dementia. As cognitive decline is also influenced by lifestyle factors, we investigated, in the present study, to what extent the APOE gene may determine the strength of associations between lifestyle factors and the level of cognitive functioning.

Methods: In the LIFE-ADULT-Study, a large population-based study on inhabitants of the city of Leipzig, Germany, 10,000 participants (aged 40 – 79 years old) underwent cognitive testing (Trail-Making Test, Verbal Fluency Test), provided blood samples as well as information on lifestyle factors in standardized interviews and questionnaires. Data analyses comprised multivariate regression and generalized linear modeling.

Results: Analyses indicated significant associations between the socioeconomic and lifestyle factors being socially isolated, having a low income, a low occupational status, being unemployed, not having an undergraduate or graduate diploma, a low level of physical activity and more package-years smoked on a poorer cognitive functioning – independent of the APOE genotype. Interaction effects between the APOE e4-allele and socioeconomic and lifestyle factors regarding a poorer cognitive functioning seemed to be age-sensitive.

Conclusions: The results suggest that overall cognitive functioning of individuals with and without the APOE e4-allele may be comparably associated with socioeconomic and lifestyle factors. APOE genotype-specific differences of such associations possibly emerge with older age. Understanding aging processes, thus, will be an essential element in understanding mechanisms of how genetic and environmental factors affect dementia development and progression.