Background: Ageing is associated with a slowing and hesitancy of gait, and in some, this may take the form of a more serious gait apraxia. Greater volume of cerebral white matter lesions (WML) is associated with poorer gait. One possible causal mechanism for this is that WML disconnect neural networks specifically involved in gait. We hypothesised that WML associated with gait impairment are preferentially distributed in regions related to the control of gait.
Methods: High-resolution brain MRI and computerised gait analysis were performed on 385 participants in the population-based Tasmanian Study of Cognition and Gait (TASCOG). A composite gait factor was derived using factor analysis. Semiautomated segmentation was used to identify lesion-affected voxels. The multivariate voxel-based method of partial least squares regression was used to determine which systems of WML voxels showed greatest covariance with gait independent of other WML voxels.
Results: Systems of WML affected voxels in bilateral frontal and periventricular regions demonstrated greatest covariance with poorer gait. The location of these voxels corresponded mainly to major anterior projection fibres (anterior and superior thalamic radiations, corticopontine and corticospinal tracts), adjacent parts of anterior association fibres (corpus callosum, superior longitudinal fasciculus, short association fibres).
Conclusion: WML may contribute to age-related gait decline by disrupting frontally located afferent and efferent projection and association tracts known to be involved in the execution of planned movement.