Volume 15, Number 12
One of the fears that commonly accompanies aging is the possibility of memory decline, whether that be from ordinary aging of the brain or from a dementing condition such as Alzheimer’s disease. Naturally, this fear can prompt interest in identifying behaviors that can preserve memory function. Two such strategies that have research support are regular physical activity and cognitive enrichment activities.
The hippocampus is a structure in the limbic system of the mammalian brain that has a significant role in both learning and memory, and tends to decline in function as the organism ages. Exercise and cognitive stimulation have been shown to help preserve hippocampal function.
Elizabeth Kirby, PhD, a behavioral neuroscientist, conducts investigations of the impact of social networks on cognitive function in her laboratory at The Ohio State University. One of her interesting studies was published in Frontiers in Aging Neuroscience in 2018. This study was conducted with mice, aged 15-18 months, a period marked by memory decline in rodents. Some mice were housed in pairs, while others lived in groups of seven. All the mice were subjected to a number of cognitive and memory challenges. What Dr. Kirby and her colleagues found was that the group-housed mice consistently performed better on memory tests, and were found to employ more effective learning strategies. When brain tissue of the mice was subsequently examined, no disparities in neurogenesis (the birth of new neurons) were found that could have explained the differences in memory performance. What was evident was that there was less inflammation in the brains of the group-housed mice, including in the hippocampus.
There have been human studies indicating that larger social networks are associated with better preserved memory function, and there have been a number of theories about why this is. One is that having a larger social network results in greater access to services that are important for physical health, such as community resources and health-related information. However, in Kirby’s mice study, the physical environment and care provided to the mice was identical in the two groups. Another theory is that social relationships help buffer stress, a theory that has been supported in human studies. This did not appear to be a factor in Kirby’s research, however, as no differences in stress indicators were found in the mice groups, including analysis of corticosterone. A third theory explaining the association between having more ties to social groups and preserved memory function is that group interaction promotes cognitive demand and stimulation. This “cognitive enrichment hypothesis” is supported by the findings of Kirby’s mice research.
Regular physical activity and cognitive stimulation are certainly important in the interest in preserving cognitive function as individuals get older. And while there appears to be benefit from solitary cognitive stimulation, such as challenging games or puzzles, Kirby’s research suggests that the cognitive stimulation that comes with social interaction should also be prioritized, a conclusion that is warranted from existing human studies.
Although mice living in pairs had more memory decline than those living in groups, this research should not be interpreted as minimizing the importance of the health benefits of having a high quality relationship with a significant other. Numerous benefits come with intimate relationships. However, there can be much familiarity in relationships with long-standing significant others, so that interaction may not present considerable cognitive challenge. The cognitive stimulation that Kirby and others have identified as memory-preserving appears to come through interaction with others beyond one’s intimate relationship, highlighting the importance of also nurturing other social relationships as one ages.
Paul J. Hershberger, Ph.D.
… is a clinical health psychologist. He is Professor, Director of Research, and Director of the Division of Behavioral Health, Department of Family Medicine, Wright State University Boonshoft School of Medicine.
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