Cortical structural involvement and cognitive dysfunction in early Parkinson’s disease
Klein JC., Rolinski M., Griffanti L., Szewczyk-Krolikowski K., baig F., Ruffmann C., Groves AR., Menke R., Hu M., Mackay C.
Introduction MRI studies in early Parkinson’s disease (PD) have shown promise in the detection of disease-related brain changes in the white and deep grey matter. We set out to establish if intrinsic cortical involvement in early PD can be detected with quantitative MRI. Methods We collected a rich, multi-modal dataset including diffusion MRI, T1 relaxometry, and cortical morphometry in 20 early PD patients (disease duration 1.9±0.97 years, Hoehn & Yahr 1-2), and 19 matched controls. Cortex was reconstructed using FreeSurfer. Data analysis employed linked independent component analysis (ICA), a novel data-driven technique that allows for data fusion and extraction of multi-modal components before further analysis. For comparison, we performed standard unimodal analysis with a general linear model (GLM). Results Linked ICA detected multi-modal cortical changes in early PD (p=0.015). These comprise fractional anisotropy reduction in dorsolateral prefrontal, cingulate, premotor cortex and the superior parietal lobule; mean diffusivity increase in the mesolimbic, somatosensory and superior parietal cortex, sparse diffusivity decrease in lateral parietal and right prefrontal cortex; and sparse changes to cortex area. In PD, the amount of cortical dysintegrity correlated to diminished cognitive performance. Importantly, unimodal analysis detected no significant group difference on any imaging modality. Conclusions We detected microstructural cortical pathology in early PD using a data-driven, multi-modal approach. This pathology is correlated with diminished cognitive performance. Our results indicate that early degenerative processes leave an MRI signature in the cortex of patients with early PD. The cortical imaging findings are behaviorally meaningful, and provide a link between cognitive status and microstructural cortical pathology in early PD patients.