Cardiopulmonary Correlates of Cognition in Systemic Lupus Erythematosus

Objective We aimed to evaluate the relationship between cognitive dysfunction and lung function, exercise endurance, and self-reported activity levels in patients with systemic lupus erythematosus (SLE).Background Cognitive dysfunction is present in 20%-60% of SLE patients. No studies to date have investigated the inter-relationships between cardiopulmonary factors and cognition in this population.Methods Thirty-seven SLE patients without overt neuropsychiatric histories and 16 healthy controls completed neuropsychological testing, measures of lung function, exercise capacity (distance walked during a timed walk test,(1) maximal oxygen uptake(2)), and exercise questionnaires.Results Thirty-two percent of SLE patients demonstrated cognitive impairment. Cognitive impairment was correlated with Six-Minute Walk Distance (6MWD) (r=0.37, p=0.02) and certain measures of lung function. Also, in SLE patients, self-reported physical activity was correlated with 6MWD (p=0.012), but none of the more complex measures of physical activity (VO(2)max).Conclusions Patients with mild SLE disease activity have cognitive dysfunction associated with certain objective markers of exercise capacity and activity levels. The lack of associations between self-report activity and VO(2)max suggests the possibility that multiple factors mediate the relationships between perceived and actual physical ability. Additional studies are needed to better understand the relationship between cognition and physical activity in patients with SLE.