The Effects of Corpus Callosum and Cortical Connectivity on Motor Function in Cognitively Intact Elderly (P03.093)

Abstract

Objective: Determine the effects of regional corpus callosum connectivity on motor function in the elderly. 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)have been observed with age and are associated with motor decline. The relationship between the degree of CC connectivity to cortical motor regions and gait and balance function in cognitively intact older people is unknown. Design/Methods: 29 cognitively intact volunteers underwent diffusion tensor MRI and motor testing including gait speed, balance, and time able to stand on one leg (OLS). The CC and cortical target regions were segmented for each individual. Probabilistic diffusion tractography was performed (probabilistic index of connectivity, PICo, algorithm) using CC voxels as seed points and predefined cortical areas as path targets. The CC was delineated into separate topographic regions based on voxels determined to have maximal connections to cortical areas. The relationship between mean PICo values for each CC region and motor outcomes were examined using multiple regression analyses adjusted for age. Results: Increased age was associated with decreased PICo values (connectivity) to the premotor, pre-central, and paracentral gyri for voxels with strongest connectivity to those regions. After adjusting for age, diminished gait speed was associated with decreased PICo values to the precentral and paracentral cortices while poorer balance function (Tinetti balance testing and OLS) was associated with 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 in cognitively intact elderly, and may be an early marker of those at increased risk of falls and cognitive decline. Supported by: NIH (P30 AG08017, M01 RR000334, R01 AG024059), Department of Veterans Affairs, Storms Family Fund at the Oregon Community Foundation, T&J Meyer Foundation. Disclosure: Dr. Silbert has nothing to disclose. Dr. Perkins has nothing to disclose. Dr. Lahna has nothing to disclose. Dr. Kaye has received personal compensation for activities with Eli Lilly & Company as a participant on a data safety and monitoring board. Dr. Kaye has received research support from Elan Corporation, Danone Medical, Bristol-Myers Squibb Company, Satoris, and Intel.