Aging is often associated with increased distractibility that may arise from a failure to adequately suppress the processing of irrelevant sensory information. In our recent Cerebral Cortex paper, we show that decreasing word intelligibility was associated with increasing visual cortex activity in younger, middle-aged, and older adults. In addition, age was related visual cortex activity: while younger adults suppressed visual cortex activity during listening, aging was associated with reduced suppression and increasing visual cortex activity. Our findings guide the prediction that both age and listening difficulty impact the likelihood that irrelevant sensory information will be distractible.Alternatively, this change could reflect the engagement of multi-sensory representations to help identify speech in difficult listening conditions.
Older adults experience slowed processing speed and the severity of slowed processing speed is a strong predictor of age-related cognitive decline and independence. In our recent manuscript in the journal Frontiers in Neuroscience we review the structural changes observed in brains of older adults that occur with slowed processing speed. The most consistently observed structural changes occur in frontal brain regions that are susceptible to micro-vascular disease and cerebellar regions that together appear to constitute declines in neural systems important for coordinating and adapting behavior. Frontal/cerebellar systems may therefore be targets for understanding the efficacy of interventions designed to enhance healthy aging.
The most consistent and pronounced factor that affects the cognitive abilities of older adults is a decline in processing speed, or the rate at which people can perform a task. Links between processing speed and changes in frontal lobe cortex, which appear to be mediated in part by cerebral vessel disease, have been reported previously. Similar results are presented in our recent Frontiers of Human Neuroscience paper, as well as evidence that age-related changes in cerebellar cortex uniquely predict age-related changes in processing speed. Cerebellar cortex did not appear to be substantially affected by vessel disease, suggesting different mechanisms for cerebellar and frontal changes that affect processing speed. These results are important because potential lifestyle and intervention programs designed to limit the effects of aging on cognition could have greater efficacy by targeting distinct cerebellar and frontal systems.
Changes in auditory temporal processing are thought to be one reason why older adults have difficulty recognizing speech, especially in difficult listening conditions. Dr. Kelly Harris reports in the journal Hearing Research that changes in auditory temporal processing can be explained, in part, by changes in cognitive processing speed. Processing speed is the rate at which people can perform behavioral tasks and has been linked to brain regions important for directing attention. One potential implication of Dr. Harris’ findings is that age-related changes in speech recognition occur, in so far as they are related to auditory temporal processing, because of changes in brain regions important for directing attention.