Cognitive impairment in elderly women: the relative importance of selected genes, lifestyle factors, and comorbidities

Henrik Berg Rasmussen¹, Yu Z Bagger², László B Tankó², Gerong Qin², Claus Christiansen², Thomas Werge¹

¹Research Institute of Biological Psychiatry, H:S Sct. Hans Psychiatric Hospital, University of Copenhagen, Roskilde, Denmark; ²Center for Clinical and Basic Research, Ballerup, Denmark

Background: A variety of factors contribute to the development of cognitive impairment in elderly people. Previous studies have focused upon a single or a few risk factors. In this study we assessed and compared the significance of a wide variety of potential risk factors for cognitive impairment in postmenopausal women.

Methods: A total of 208 pairs of elderly women (mean age = 73.2 years) were examined in a cross-sectional case-control study. Each pair consisted of a case (with impaired cognition) and a control subject matched by age and educational status. Cognitive functions were determined using a modified version of the Blessed test. Participants were also subjected to a general clinical examination and they were interviewed to collect information on lifestyle practices and comorbid disorders. Genotypes for the apolipoprotein E (APOE) epsilon4, catechol-O-methyltransferase (COMT) Val/Met, and brain-derived neurotropic growth factor (BDNF) Val/Met polymorphisms were determined. Data were analyzed by conditional logistic regression.

Results: We identified a set of risk factors for age-related cognitive impairment. A statistical model for assessment of the importance of these factors was constructed. The factors in this model were physical exercise (odds ratio [OR] = 0.50, 95% confidence interval [CI] = 0.32–0.78), regular alcohol consumption (OR = 0.49, 95% CI = 0.29–0.83), metabolic syndrome (OR = 2.83, 95% CI = 1.26–6.39), depression (OR = 3.24, 95% CI = 1.28–8.22), and the APOE epsilon4 allele (OR = 1.76, 95% CI = 1.09–2.83). Also COMT genotype was present as a risk factor in the statistical model (p = 0.08).

Conclusions: Lifestyle risk factors, comorbid disorders, and genetic factors contribute to development of age-related cognitive impairment. The two former groups of risk factors appear to be particular important in this respect.

Keywords: age-related cognitive impairment, risk factors, lifestyle choices, comorbid disorders, genetic susceptibility