As we age, it’s common for our thinking to become slower as a result of changes in the brain. But how, exactly, does this happen? In this study, researchers aimed to establish a direct relationship between neural slowing and brain atrophy. They combined magnetoencephalographic (MEG) measures of brain processing speed with magnetic resonance imaging (MRI) measures of brain structure to investigate how age-related changes in the brain led to slower visual and auditory processing. Using a novel technique, the researchers showed that white matter microstructures in the brain mediates visual processing delays, suggesting that visual information transmission in the brain slows with age. Auditory processing, however, slows due to changes in grey matter. This suggests that auditory processing gets worse with age due to localised changes in the brain. The findings of this study demonstrate that age has dissociable effects on neural processing speed, and that these effects are due to different types of brain atrophy over time.

Citation: Price, D., Tyler, L.K., Henriques, R.N., Campbell, K.L., Williams, N., Treder, M.S., Taylor, J.R., Cam-CAN, & R.N.A. Henson. (2017). Age-related delay in visual and auditory evoked responses is mediated by white- and grey-matter differences. Nature Communications, 8, 15671.
doi: 10.1038/ncomms15671