Gender and Education Does Not Necessarily Impact Cognitive Decline
SEPTEMBER 05, 2019
Kay Deckers, PhD
A team, led by Kay Deckers, PhD, Alzheimer Centrum Limburg, School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands, examined 2347 cognitive healthy participants from the Doetinchem Cohort Study for cognitive function at baseline, as well as at a 5-and-10-year follow-up and captured health and lifestyle factors using a poly-environmental risk score called ‘LIfestyle for BRAin Health’ (LIBRA).
The study population had a mean age of nearly 55-years old, 52% of which were female and 26% were low education individuals. The Doetinchem Cohort Study is an ongoing prospective cohort study that aims at evaluating the impact of lifestyle and biological risk factors on various aspects of health.
The LIBRA score consists of 12 modifiable risk and protective factors for cognitive decline and dementia, with higher scores indicating greater risk (-2.7-12.7). The team assessed heterogeneity in associations between LIBRA and decline in verbal memory, cognitive flexibility, and mental speed between males and females and individuals with different levels of educating using linear mixed models.
The risk factors included coronary heart disease, diabetes, hypercholesterolemia, hypertension, depression, obesity, smoking, physical inactivity, and renal disease. Protective factors were low-to-moderate alcohol use, high cognitive activity, and healthy diet.
The investigators developed the 15 Words Verbal Learning Test (VLT), the Stroop Color Word Test (SCWT), and the Letter Digit Substitution Test (LDST) to evaluate cognitive changes over time.
A composite risk score comprising unhealthy lifestyle and poor health in midlife is substantially linked to a worse course of cognition 10 years later, which were for the most part unrelated to gender or educational differences.
“Overall, higher LIBRA scores predicted faster decline in verbal memory, cognitive flexibility, and mental speed over 10 years,” the authors wrote. “Higher LIBRA scores were further associated with increased risk for incident cognitive impairment (1-point increase in LIBRA: HR, 1.09, 1.04–1.14, P = .001). In general, these effects were similar across gender and educational level.”
The investigators did find some differences between the 2 sexes, where males were on average higher educated, had higher presence of coronary heart disease and hypertension, had less depressive symptoms, were less often low-to-moderate alcohol drinkers, had higher LIBRA scores, and had lower scores on all 3 cognitive functions in comparison with females.
They also found that participants with a low educational level were on average older, more often female, had a higher presence of hypercholesterolemia, obesity, and hypertension, had more depressive symptoms, were more often smokers, were more often low-to-moderate alcohol drinkers, adhered less often to a healthy diet, had higher LIBRA scores, and had lower scores on all 3 cognitive functions in comparison with persons with a medium or high educational level.
The researchers said the study results could help identify risk groups that could benefit from preventative measures in the general population.
They also suggested that future studies could look at the mediation effects of various biological factors, such as genetics, hormones and brain networks, in relation to the observed associations. More studies are also needed to assess gender differences rather than just adjusting for gender in analysis.
According to the investigators, approximately 33% of all Alzheimer disease cases globally has been linked to common modifiable risk factors under the causality assumption.
The study, “Gender and Educational Differences in the Association between Lifestyle and Cognitive Decline over 10 Years: The Doetinchem Cohort Study,” was published online in the Journal of Alzheimer’s Disease.