Introduction: Offspring of parents with a mood disorder have a strong risk of developing a mood disorder and displaying cognitive deficits compared to healthy controls. Research shows...Show moreIntroduction: Offspring of parents with a mood disorder have a strong risk of developing a mood disorder and displaying cognitive deficits compared to healthy controls. Research shows positiveassociations between sleep and cognitive performance and exercise and cognitive performance in the general population. The present cross-sectional study aimed to identify a relationship between sleep, exercise and cognitive performance in adolescents at high-risk for severe mental illness. It was expected that regular exercise or adequate sleep duration has a significant and positive association with cognitiveperformance in adolescents at high-risk for severe mental illness. Methods: Data were collected by the Mood and Resilience in Offspring (MARIO) study, a longitudinal study investigating the transmission of mood disorders between parents and offspring. In total, 146 participants from both a high-risk and control group were included and filled in questionnaires about sleep, exercise and depressive symptoms. They also completed two subtests (matrix reasoning and vocabulary) of the WISC-V or WAIS-IV. Multiple regression analyses were conducted to test whether there was a positive relationship between exercise, sleep and cognitive performance in adolescents at high-risk for severe mental illness and controls. Results: The analyses showed no significant association between exercise and matrix reasoning (β = -.02, p = .873) and vocabulary (β = .21, p = .146). Moreover, there was no significant association between sleep duration and matrix reasoning (β = -.06, p = .506) or vocabulary (β = -.07, p = .465). Furthermore, depressive symptoms did not moderate the relationship between sleep, exercise and cognitive performance. Sensitivity analyses, including only high-risk participants, did not reveal any additional insights. Conclusions: Contrary to the hypotheses, our findings show no positive association between adequate sleep duration and/or regular exercise and cognitive performance in adolescents at high-risk for severe mental illness. Offspring of parents with a mood disorder form a vulnerable group. Future research is therefore needed to better understand mood symptoms and cognitive deficits in offspring of parents with mood disorders. Keywords: sleep duration, exercise, cognitive performance, high-risk, mood disorderShow less