Age at illness onset and physical activity are associated with cognitive impairment in patients with current diagnosis of major depressive disorder

Abstract

Background: Cognitive impairment has been reported in patients with Major Depressive Disorder (MDD). This study aims to explore the association between lifestyle habits and health-related factors and the presence of cognitive symptoms in MDD patients.

Methods: Demographic, clinical, health-related variables and cognitive scores measured with the Cambridge Neuropsychological Test Automated Battery (CANTAB) were compared between 74 patients with current MDD and 68 healthy controls (HC). To test the hypothesis of associated factors to cognitive symptoms, multivariate backward stepwise linear regression models were run.

Results: Significant neuropsychological deficits were evident in MDD compared with HC in the global cognitive index (F=8.29; df=1, 140; p=0.005). In the regression analysis performed on MDD and HC, years of schooling (β=-0.11; p=<0.001), job status (β=-0.50; p=0.016), physical activity (β=-0.25; p=0.04) and age at illness onset (β=0.17; p=0.017) were statistically significant factors associated to cognitive impairment. The regression model ran in HC showed that only years of schooling were significant (β=-0.07; p=<0.001) in this group.

Limitations: Sample size was relatively small. Everyday cognitive skills were not evaluated.

Conclusions: MDD patients have cognitive deficits. These deficits are linked with the years of education, job status, age of onset of the disease and the performance of physical activity. These results support the importance of the implementation of interventions targeting the cognitive reserve and lifestyle habits of MDD patients, in addition to the conventional therapeutic approach focused on symptoms control.

Keywords: Age of onset; Cognitive impairment; Health-related variables; Major depressive disorder; Physical activity; Years of schooling.