Dr. Wolk returned to discuss Aging. Basic concerns with this area surface when you consider the data that we are seeing a Significant increases in proportion of elderly in developed countries due to reduced birth rates; increased longevity so that by 2050, 26% older than 65 year olds with only and 15% younger than 15 year olds. Increase creating questions of both “Healthy” cognitive aging and pathological cognitive aging. For instance age is the greatest risk factor for Alzheimer Disease so that the prevalence doubles every 5 years after age 65. So researchers are concerned about optimization of cognitive health. Good news is that there is a wealth of data now from fMRI studies and other sources.
The losses in the aging seem to emerge from a variety of areas around the prefrontal cortext leading to a Frontal Hypothesis of Aging including loss in
Speed of processing decline: Perceptual speed (same/different)
Working Memory Deficiency: Reduced capacity
Loss of inhibition: Inefficient – slows processing and disrupts working memory
Controlled processing deficit: Reduced top-down control/strategic processing
Yes we do see correlation with structural changes (reduction of hippocampus but also increase in white matter injury and other issues) but overall these correlations prove “fuzzy” so researchers are now looking for functional changes that may account for additional variance (so yes shrunken cortext but real issue is older adults are just under-recruiting aspects of the brain like the VLPFC). However, if you give the adults a semantic tasks (like forming sentences rather than just recalling words) these older adults can enhance memory. Question raise whether older adults develop other compensatory actions that might be either less efficient or just alternative but the overall view seems to indicate the overall evaluation is more complicated. There does seem to be some ways to offset aging including:
- Physical Exercise
Reduction of cerebrovascular risk factors
Psychosocial factors including
- Social networks
One question revolves around if people live longer are we all “determined” to outlive brains (contract Alzheimers?) probably not (AD is a disease) but there are long term health concerns so learning to delay cognitive loss remains a key question.