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P2‐351: Probabilistic diffusion tractography of the corpus callosum and motor function in the elderly
Author(s) -
Silbert Lisa,
Sherbakov Lena,
Perkins Louie,
Kaye Jeffrey
Publication year - 2011
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2011.05.1228
Subject(s) - diffusion mri , tractography , voxel , corpus callosum , gait , fractional anisotropy , white matter , neuroscience , psychology , premotor cortex , physical medicine and rehabilitation , anatomy , medicine , computer science , artificial intelligence , magnetic resonance imaging , radiology , dorsum
Background: Motor dysfunction in the elderly is common, and associated with increased risk of falls and cognitive decline. Microstructural changes to the corpus callosum (CC), including decreased fiber tract directionality and increased water molecule diffusion, have been observed with age and are associated with motor dysfunction. The relationship between the degree of CC connectivity to specific cortical regions and gait and balance function in brain aging is unknown.Methods: 29 cognitively intact elderly subjects underwent structural and diffusion tensor MRI and neurological testing including gait, Tinetti balance, and time able to stand on one leg on the left (OLS-L) and right (OLS-R). The CC and cortical target regions (prefrontal, premotor, pre-central, post-central, para-central, parietal, temporal, and occipital cortexes) were segmented for each individual. Probabilistic diffusion tractography was performed using the probabilistic index of connectivity (PICo) algorithm, modeling the degree of uncertainty in the orientation of the principal diffusion direction at each voxel and running repeated iterations of aMonte Carlo process with CC voxels as seed points and predefined cortical areas as path targets. The CC was segmented into separate topographic regions based on maximum strength of connection to the given cortical area. The relationship between mean PICo values for each CC region and motor outcomes were examined using multiple regression analyses adjusted for age. Results: Increased agewas associated with decreased PICo values (connectivity) to the premotor, pre-central, post-central, and paracentral gyri for voxels with strongest connectivity to those regions. After adjusting for age, diminished gait speed (steps and time to walk 30 feet) was associated with decreased PICo values to the precentral, post-central and paracentral cortices while poorer balance function (Tinetti balance testing andOLS) was associatedwith decreased PICo values to the pre-motor, precentral, and paracentral gyri. Conclusions: Advanced age is associated with decreased PICo of the principal diffusion direction in CC voxels with strongest connectivity to cortical areas involved in motor function. Decreased CC connectivity to the motor cortex is associated with poorer performance on gait and balance function tests and may be an early marker of those at increased risk of falls and cognitive decline.