Cognitive aging, executive function and fractional anisotropy: A Diffusion Tensor MRI study.

Grieve SM Williams LM, Paul RH, Clark CR & Gordon E. (2007). Cognitive aging, executive function and fractional anisotropy: A Diffusion Tensor MRI study, American Journal of Neuroradiology, , 226-235.



BACKGROUND AND PURPOSE: Fractional anisotropy (FA) is a useful measure of connectivity in the brain and can be easily derived from the diffusion tensor imaging (DTI) dataset. This study investigated the relationship between selected measures of cognition thought to involve the frontal lobes and FA across a broad age group in order to explore a possible structural basis for cognitive changes with age. METHODS: FA images were generated from DTI data acquired at 1.5 T in 87 normal subjects (age range, 20 to 79 years). Relationships between a range of cognitive measures and FA were explored using regional and voxel-based analysis. RESULTS: Age and FA were significantly associated in the frontal, parietal and temporal lobes but not in the occipital lobe. This negative relationship was especially prominent in the prefrontal regions of the frontal lobe, where FA declined at a rate of approximately 3% per decade. Decreased FA in the frontal, temporal and parietal lobes was associated with poorer cognitive performance in executive maze and in an attention switching task. A detailed analysis of the regional basis of these observations revealed that the executive function?FA association was particularly strong in two bilateral areas extending from the prefrontal cortex, to the parietal lobe, with projections to the anterior portions of the thalamus. CONCLUSIONS: We demonstrate a relationship between FA and a measure of executive function ? a core cognitive component that is a key feature of cognitive aging. We propose that that FA may provide an early means for the detection of age-related cognitive change and suggest a need for prospective data to explore this association. .