Identifying functional brain adaptations in normal age-associated cognitive decline using FMRI

The aging brain undergoes significant changes in the absence of identified disease processes. Despite these functional brain changes, some older adults are still able to adequately perform fundamental cognitive functions, like cognitive processing speed (CPS), at expected levels. One potential explanation for individual differences in the relative retention of CPS ability is hemispheric asymmetry reduction in older adults (HAROLD). In the current study, we tested whether CPS was a lateralized neuropsychological function using FMRI, if HAROLD effects extend to CPS, and whether HAROLD effects reflect compensatory adaption. Results demonstrated that CPS ability was not preferentially lateralized, and thus, HAROLD effects did not appear to extend to CPS functioning. This is the first study to attempt to extend HAROLD model effects to this cognitive domain and has significant ramifications for other processes that attempt to explain healthy age-related cognitive decline.