Longitudinal Changes in Depression and Cognition in Professional Fighters with Baseline Structural Imaging: The Role of Depression in Cognitive Change and Structural Differences

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Objective: Depression and cognitive decline are common sequelae of repetitive head injury, and have been shown to be important markers for underlying neuroanatomic function. Additionally, depression has been shown to be strongly related to cognition in those with brain injuries. Longitudinal data addressing these observations are needed. Background: No studies to date, however, have examined longitudinal cognitive and depression data in the context of a well-characterized population with baseline imaging data. As such, it is difficult to know whether these point-in-time observations translate into change over time, and additionally what role depression may play in cognitive change. Design/Methods: A subset of 108 professional boxers and MMA fighters completed a baseline MRI, and serial cognitive/ mood screening as part of an ongoing longitudinal study. Brain regions were identified a priori to examine relationships between exposure to head injury and neuroanatomic, cognitive, and affective variables. Relationships among baseline scores were assessed via partial correlations accounting for age and whole brain volume. Hierarchical regression was used to assess for mediation. Results: Exposure to repetitive head injury was significantly related to reduced volumes in the left (r = −.21) and right (r = −.22) hippocampi, left amygdala (r = −.22), and right caudate (r = −.22) as well as depression (r = .33) and poorer inhibition (r = .40), processing speed (r = −.25), and psychomotor speed (r = −.23). Depression at baseline was significantly correlated with left hippocampal volume (r = −.21), left insular thickness (r = −.20), psychomotor speed (r = −.23), and inhibition (r = −.27) at baseline. Although bilateral medial orbitofrontal cortex volume at baseline predicted inhibition change over time (R = .29), baseline depression mediated this relationship. Conclusions: Depression emerged as an important clinical phenotype related to brain structure volume in this population and a key factor in predicting cognitive change over time.


Neuroscience and Neurobiology



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