Cardiorespiratory fitness and its association with thalamic, hippocampal, and basal ganglia volumes in multiple sclerosis

Background There is little known about cardiorespiratory fitness and its association with volumes of the thalamus, hippocampus, and basal ganglia in multiple sclerosis (MS). Such inquiry is important for identifying a possible behavioral approach (e.g., aerobic exercise training) that might change volumes of deep gray matter (DGM) structures associated with cognitive and motor functions in MS. Purpose This study examined the association between cardiorespiratory fitness and volumes of the thalamus, hippocampus, and basal ganglia in MS. Method We enrolled 35 persons with MS who underwent a maximal exercise test for measuring cardiorespiratory fitness as peak oxygen consumption (VO_2peak) and brain MRI. Volumes of the thalamus, hippocampus, caudate, putamen, and pallidum were calculated from 3D T1-weighted structural brain images. We examined associations using partial (pr) correlations controlling for demographic and clinical variables. Results VO_2peak was significantly associated with composite scaled volumes of the caudate(pr =.47, p <.01), putamen (pr =.44, p <.05), pallidum (pr =.40, p <.05), and hippocampus (pr =.42, p <.05), but not thalamus (pr =.31, p =.09), when controlling for sex, age, disability, and duration of MS. Conclusion Our results provide novel evidence that cardiorespiratory fitness is associated with volumes of DGM structures that are involved in motor and cognitive functions in MS.