Association between physical fitness and cerebral grey matter integrity in patients suffering from Parkinson's disease, a structural MRI study

Introduction/Background Being physically active protects the elders against cerebral grey matter (GM) loss in regions particularly exposed to aging [1]. This cross-sectional study extended this hypothesis by searching correlations between volume or microstructure of GM and physical fitness in the nigrostriatal system of patients suffering from Parkinson's disease (PPD). Material and method Cerebral grey matter volume (GMV), magnetization transfer (MT) and R2* (an index of local iron) parameters were extracted from whole brain 3 T MRI and were analysed voxel-by-voxel using SPM12 in 42 PPD and 32 matched healthy controls (HC). All subjects were also tested for Peak work load (PWL) and knee flexor strength (KFS). First, we performed a two-sample t-test to look at areas affected in the nigrostriatal system of the PPD in comparison to HC. Next, we used a regression analysis to test which of these regions, if any, showed a relationship between (1) GMV, MT or R2* and (2) individual PWL or KFS. Results The comparative study showed increased R2* in bilateral SN, reduced GMV and increased R2* in left and right striata (Puncorrected < 0.001). In PPD, GMV in the head of the right caudate nucleus and anterior putamen showed a positive correlation with PWL and GMV (Pcorrected < 0.023). Besides, GMV in this cluster also correlated with global cognitive performance assessed by the Mattis Dementia Rating Scale (Pcorrected < 0.024). None of the disturbed regions correlated with KFS. No significant correlations were observed in these regions for HC. Conclusion Aerobic fitness may have a specific neuroprotective effect on the right anterior striatum of PPD, and this could be associated with better cognition.