Abstract
BACKGROUND: In healthy (non-psychotic) controls, caffeine intake is associated with better performance in attention, memory, and processing speed. These domains typically are those impaired in schizophrenia patients. Despite the fact that schizophrenia patients consume three times more caffeine than the general population, only one study has looked at the cognitive effects of caffeine on schizophrenia patients. That study found that caffeine intake was associated with better working memory, visual memory, processing speed, and semantic fluency. The association of caffeine use and symptomatology is also unclear. The purpose of this cross-sectional study is to investigate the association among chronic caffeine use, cognition, and symptomatology in patients with schizophrenia. METHODS: Fourteen (14) schizophrenia patients have been recruited to date. Participants are asked to consume their regular caffeine dose 45 minutes prior to participation. During their study visit, participants are rated with the Positive and Negative Syndrome Scale (PANSS) and are administered the Cogstate Battery. Participants self-report their average daily caffeine intake. RESULTS: Hierarchical regression analysis assessed the relationship among caffeine intake, symptoms (positive, negative, and cognitive factors), and cognition (processing speed and sustained attention). The overall regression model for the Detection Task (i.e., processing speed task) and Identification Task (i.e., sustained attention task) predicting caffeine intake is borderline significant F(2,11) = 3.79, p = .056, R2 = 0.41. Holding all variables constant, Detection Task (β = 32.78, p = 0.02) and Identification Task (β = -22.70, p = 0.089) significantly predicted caffeine intake. Symptoms did not predict caffeine intake F(3,10) = .76, p = 0.544, R2 = 0.19. DISCUSSION: While symptoms do not predict caffeine intake, a one-unit increase in the processing speed task (i.e., Detection Task) predicts an increase in caffeine intake while a one-unit increase in the sustained attention task (i.e., Identification Task) predicts a decrease in caffeine intake. Sample size is currently small, and these results do not rule out a curvilinear relationship between symptoms/cognition and caffeine intake. Further investigation into the relationship among caffeine intake, cognition, and symptomatology is necessary given the limited literature. It is possible some schizophrenia patients are benefiting from caffeine intake.