Cortical thinning and white matter tract damage in relation to cognition in motor neuron diseases (P6.087)

Objective: To assess the patterns of cortical thinning and white matter (WM) tract abnormalities in relation to cognition and behavioural symptoms in patients with motor neuron disease (MND). Methods: 101 patients with motor neuron disease (MND) and 56 healthy subjects were studied. Patients were classified into MND with a pure motor syndrome (MND-motor) and those with cognitive/behavioural symptoms (MND-plus). A surface-based morphometry analysis was used to assess cortical thickness. Corticospinal tract (CST), corpus callosum (CC), and major association tracts diffusion tensor (DT) metrics were obtained. A Random Forest (RF) approach was used to identify the set of image features correlated with cognitive/behavioural deficits. Results: There were 48 MND-motor and 53 MND-plus patients. Relative to controls, both patient groups showed cortical thinning of the bilateral precentral and postcentral gyri, cingulate cortex, inferior temporal and parietal areas. In all regions, there was a trend towards a more extensive involvement in MND-plus vs MND-motor. Both patient groups showed a damage of the motor CC fibers, but such a damage was greater in MND-plus cases. MND-plus patients also showed a severe involvement of the extra-motor WM tracts bilaterally. RF analysis showed that the best predictors of cognitive deficits and behavioural symptoms in MND patients were the DT MRI metrics of the frontotemporal tracts. Conclusions: Cortical thinning and WM degeneration are highly dependent upon neuropsychological and behavioural symptoms in patients with MND. WM tract damage contributes to the severity of selective cognitive and behavioural manifestations more than cortical thinning. Study Supported by: Italian Ministry of Health (#RF-2010-2313220).