Presenter: Patrick J. Glang
Mentor: Deborah M. Little
Oral Presentation
Major: Psychology
Across all severities of traumatic brain injury (TBI), deficits in mood and emotion regulation are commonly reported. In moderate to severe brain injury, the incidence of depression has been found to be as high as 77%. Milder TBI (mTBI) showed an increased in depression and self-reported cognitive problems. The cause is unknown. The structure, location, and the functional role of the cerebellum in depression affect regulation. We hypothesized that TBI is associated with shearing and straining in the cerebellum. This associates with the severity of depressive symptoms. The objective of this study was to assess the association of damage to white matter tracts in the cerebellum and depressive symptoms in chronic TBI. High resolution diffusion tensor imaging (DTI) was carried out. Patients with a history of a single closed-head injury (n=24 mTBI and 24 moderate to severe TBI) were matched to controls.
Fractional anisotropy (FA), radial, and axial diffusivity were extracted from regions of interest (ROI) in the pontine crossing tracts, middle and superior cerebellar peduncles, portions of the cortico-spinal tract, and medial lemniscus (bilaterally when appropriate). A total of 3 ROIs were placed on each tract. Regions were drawn independently by two raters with an inter-reliability of 0.91. A history of moderate to severe TBI showed reduced FA in all ROIs compared to healthy controls. The mTBI differed (decreased FA) from controls in the medial lemniscus, pontine crossing tracts, and in the inferior region in the cortico-spinal tract. Depressive symptoms (determined by the Beck Depression Inventory II) weren’t associated with FA for controls for any ROI(p=0.09). For mTBI, FA of the medial lemniscus was correlated with total BDI score (p=0.006). For the moderate to severe TBI, there were correlations between depressive symptoms and FA in the pontine fibers (p=0.04), cortico-spinal tract (p=0.02), and superior cerebellar peduncles (p=0.04). This study provides preliminary evidence that structural alterations in the cerebellum are associated with increased depressive symptoms in TBI.