Brain Health Across the Life Span Proceedings of a Workshop (2020) / Chapter Skim
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6 Brain Health in the Social Context
6 Brain Health in the Social Context
Pages 81-106
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From page 81... ...
(Jennifer Manly) • Brain health disparities research must measure life-course individual or contextual factors, such as social determinants of health or the social exposome, sufficiently well to deter mine the relative contributions of bio-psycho-behavioral social factors to disease or interactions.
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From page 82... ...
Understanding the neuro pathological mechanisms underlying brain health disparities will require studying people earlier in life. (Jennifer Manly)
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From page 83... ...
Social resilience is inherently a multilevel construct -- revealed by capacities of individuals and also groups -- to foster, engage in, and sustain positive social relationships and to endure and recover from social stressors and social isolation (Cacioppo et al., 2011)
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From page 84... ...
A person can feel "lonely in a crowd" when public speaking, for instance, while a person can feel extremely connected while completely alone just by thinking about loved ones. Thus, loneliness can be defined as perceived social isolation: a discrepancy between current and expected social relationships with a significant other.
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From page 85... ...
of people with different social network sizes have also revealed differences in sizes in various parts of the social brain (Cacioppo et al., 2014)
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From page 86... ...
For instance, a variety of biological mechanisms have evolved that capitalize on aversive signals to motivate behaviors that increase the chances of short-term survival. Within this framework of evolutionary theory, loneliness is like a biological signal in that the aversiveness of loneliness serves as a biological warning signal analogous to hunger, thirst, and pain.
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From page 87... ...
NOTE: IL = interleukin. SOURCE: Adapted from table presented by Stephanie Cacioppo at the workshop Brain Health Across the Life Span on September 25, 2019.
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From page 88... ...
Going forward, the temporal dynamics for the operation of loneliness and for each specific pathway need to be better understood. Another research question is to look at whether loneliness is associated with many or all of those pathways in everyone, or if it is associated with different pathways or subsets of pathways across people and social contexts.
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From page 89... ...
Damien Fair, associate professor of behavioral neuroscience, associate professor of psychiatry, and associate scientist at the Advanced Imaging Research Center at the Oregon Health & Science University, commented that it is difficult to define brain health without having a target outcome. He suggested that some of the factors Cacioppo discussed in the context of loneliness might be potential targets for brain health writ large, such as quality of life, life expectancy, and the development of psychopathologies.
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From page 90... ...
Neurobiology of Age Differences in Decision Making To help address this research gap, Samanez-Larkin's group looks at how individual and age differences in motivation and cognition influence decision making across the life span. Decision making is a capacity that
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From page 91... ...
Reinforcement learning tasks require learning quickly from experience. Early fMRI studies suggested that the age difference in reinforcement learning tasks was related, at least in part, to reduced representation of prediction errors in the medial prefrontal cortex in older adults.
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From page 92... ...
Older adults tend to be less indifferent than younger people and demonstrate a strong preference for the close social partner, who is associated with known usefulness and positive value. Based on this evidence, investigators hypothesized that the age effects on behavior, and potentially on brain function, depend on the goal relevance of the rewards.
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From page 93... ...
In this study, age differences were not observed in the medial prefrontal cortex; the adults of all ages similarly represented subjective value. This suggests that this basic value signal or usefulness signal in the brain seems to be stable across adulthood (Seaman et al., 2018)
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From page 94... ...
The researchers posited that perhaps the motivational effects and functional value signals in the medial prefrontal cortex -- a brain region that has significantly more glutamate than dopamine receptors -- functionally shift away from the dopamine system as people age. In the meta-analysis, the reported statistics yielded very large regions of interest, including the prefrontal cortex and all of the striatum.
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From page 95... ...
SOURCES: As presented by Gregory Samanez-Larkin at the workshop Brain Health Across the Life Span on September 25, 2019; adapted from Seaman et al., 2019. cortex, while the weakest effects (or no effects)
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From page 96... ...
Nielsen asked if there is any evidence that individual differences in the dopamine system are a function of life-course individual differences in impulsivity or other traits, or any evidence about individual differences in loneliness or social isolation in terms of the response to social reward tasks. Samanez-Larkin replied that this type of social engagement information is not collected very well in this arena.
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From page 97... ...
First, this research cannot be conducted using convenience samples, which proliferates in research on older adult brain health. The second challenge is that brain health disparities research must measure life-course individual or contextual factors, such as social determinants of health or the social exposome, sufficiently well to determine the relative contributions of bio-psycho-behavioral-social factors to disease or interactions.
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From page 98... ...
Evidence of racial and ethnic disparities was also found in the Kaiser Permanente Health Study in Northern California, which followed people in the health care system over many years. African Americans, American Indians, and Alaskan Natives were found to have the highest risk of developing dementia, while Asian Americans were at lower risk.
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From page 99... ...
. Researchers found that the African Americans in their study had less cerebrospinal fluid t-tau.
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From page 100... ...
This highlights another challenge: understanding the neuropathological mechanisms underlying brain health disparities will require studying people earlier in life. A more recent study found a tighter link between white-matter hyperintensity burden and cognition in African Americans than in whites (Zahodne et al., 2015)
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From page 101... ...
After controlling for early-life confounds, such as family socioeconomic status, as well as for state-level or state-fixed effects, Manly's team found that people across races who attended schools with longer term lengths had improved cognition compared to people who attended schools in states or counties that had shorter term lengths.8 Based on these data, Manly's team developed an overall score for school quality based on these administrative records. For every 1-year increase of policy-predicted years of education, people in the REGARDS study were at 40 percent lower odds of having cognitive impairment at baseline.
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From page 102... ...
Preliminary findings suggest that in general, African Americans with more education report experiencing more discrimination. Furthermore, there is interaction between sex, years of education, and discrimination on cognitive function.
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From page 103... ...
Lis Nielsen asked about how to enhance the value of datasets for studying health disparities, for example, by adding retrospective measures of social exposome variables to studies that focused on older age or by designing earlier life-course studies to incorporate those types of measures, so they will be valuable for long-term studies of aging and brain health. In terms of retrospective measures that could be added, Manly emphasized the value of retrospectively collecting and geocoding
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From page 104... ...
Manly suggested that in the context of aging brain health, it would be useful to be explicit that the trajectories of cognitive decline start much earlier in life, before they have their greatest effect on function and impose the greatest burden and cost to society. Manly also highlighted the challenge of how to measure brain health across the entire life course.
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From page 105... ...
BRAIN HEALTH IN THE SOCIAL CONTEXT 105 time periods during the life course. Even if the studies do not use the same cognitive measures or focus on the same outcomes, this strategy may be useful as a starting point for exploring potential targets and identifying critical periods across the life course.
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