Unhealthful lifestyle and low socioeconomic status (SES) are both important risk factors for late-life cognitive change. Despite numerous findings suggesting close relationships between lifestyle and SES, whether the effect of lifestyle on cognition is moderated by SES remains controversial. This effect of moderation may be important in developing targeted dementia prevention programs and reducing health disparities.
A recent study led by Professor Yen-Ching Karen Chen at the Institute of Epidemiology and Preventive Medicine, National Taiwan University, Taipei, Taiwan, collaborating with Dr. Pei-Hsuan Weng in the department of family medicine, Taiwan Adventist Hospital, found that five lifestyle factors and three SES indicators were protective against cognitive decline in elderly Chinese subjects. However, this protective effect of a healthful lifestyle was observed only among financially-disadvantaged individuals. These findings were published online in PLOS ONE on June 13.
This is a prospective cohort study conducted between 2011 and 2015. Participants aged over 65 years old were recruited from elderly health checkup programs at the National Taiwan University Hospital, Taiwan, from 2011 to 2013. Neuropsychological tests, including tests of global and domain-specific cognition (i.e., logical memory, executive function, verbal fluency and attention), were administered at baseline (N = 603) and 2 years later (N = 509). After literature review, nine lifestyle factors and three SES indicators were chosen and their effects on cognitive change were evaluated. Data on lifestyle and SES from the previous year was collected by questionnaires.
Five lifestyle factors, high vegetable and fish intake, regular exercise, non-smoking, and light to moderate alcohol consumption, and three SES indicators, annual household income (> 33,333 USD vs. less), occupational complexity (high vs. low mental demanding job), and years of education (> 12 years vs. less), were found to have a protect effect against cognitive decline after 2 years of follow up.
Significant interactions were found between a healthful lifestyle (defined as having ≥ 3 healthful lifestyle factors) and household annual income on changes in global cognition and verbal fluency. The protective effect of a healthful lifestyle was observed only among participants with lower household annual income in global cognition and logical memory. This study for the first time explored how SES moderated the association between lifestyle with cognitive change. Our findings will be useful for developing dementia prevention programs and reduce health inequalities.