This is from Psychiatry Weekly.
Psychosocial and Neural Correlates of Resilience
February 22, 2010
First published in Psychiatry Weekly, Volume 5, Issue 4, on February 22, 2010.
This interview was conducted on January 19, 2010 by Lonnie StoltzfoosIntroduction
The complex neurobiological mechanisms underlying resilience to stress have garnered greater attention over the past few years. Recent research on the biology of resilience spans a range of disciplines, including genetic, epigenetic, developmental, neuroendocrine and neural circuitry studies. Researchers are attempting to understand the relationships between these layers of inquiry, as well as interactions with environmental influences.
Definition of Resilience
There are many different definitions of resilience in the literature, according to Dr. Adriana Feder, but most definitions refer to “the capacity of an individual to adapt successfully in the face of trauma, or significant acute or chronic stressors.”
“In psychiatry we tend to define resilience as the capacity to adapt well psychologically upon exposure to significant stressors, without developing mental illness or a psychiatric disorder,” continues Dr. Feder. “But other researchers have also looked at general functioning and social relationships, and at how individuals perform at school or in their work environment.”
Resilience research first began in the 1970s with studies of children who adapted well despite significant adversity. This work identified the importance of relationships with a caring adult, social competence, and the capacity for self-regulation, among several other factors. Later research turned to identifying factors associated with resilience in adulthood. Recent technological advances have made it possible to focus on the underlying biological processes associated with resilient phenotypes.
The Psychobiology of Resilience
In a 2009 Nature Reviews Neuroscience review, Dr. Feder and colleagues highlighted several psychological attributes associated with resilience: facing fears; dispositional optimism, associated with the ability to seek and maintain social support; the capacity to reframe negative circumstances in a more positive light; and a strong moral framework, sometimes reinforced by religious beliefs.
“Ultimately, it is important to understand the biological underpinnings of these psychological attributes,” she says. And, referring to psychological characteristics identified in studies of resilient children, Dr. Feder says, “Positive emotions in children, and the capacity for self-regulation, are shaped by genetic makeup in interaction with life experiences. Understanding these different layers can help identify psychological and biological strategies that enhance resilience.”
The best-known gene-environment interaction involves a polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR). The short allele of 5-HTTLPR has been associated with decreased serotonin transporter availability, resulting in lower reuptake of serotonin. In several studies, individuals carrying this short allele have shown greater risk for depression in the face of adverse life events, including childhood maltreatment, although recent meta-analyses have questioned these findings.
According to Dr. Feder, “Additional studies have identified a range of polymorphisms of relevance to resilience, including hypothalamic-pituitary-adrenal (HPA) axis genes, as well as genes coding for a range of neurotransmitters and neuropeptides.” For example, a recent study by de Kloet and associates found that polymorphisms in the gene coding for the corticotropin-releasing hormone (CRH) type 1 receptor moderate the influence of child abuse on depressive symptoms in adulthood. It is well known that sustained high levels of CRH associated with early life trauma have detrimental effects on CNS function and general health. Some forms of this gene, however, appear to have a protective effect in the face of early trauma exposure.
Animal studies have introduced the study of epigenetic mechanisms in resilience. Epigenetics refers to long-term changes in gene expression not otherwise associated with changes in the DNA sequence. In experiments by Meaney and colleagues, the offspring of female rats displaying more nurturing behavior (high licking and grooming compared to low licking and grooming) had less methylation of the glucocorticoid receptor (GR) gene in the hippocampus, resulting in higher GR expression, lower anxiety-related behavior and better HPA axis regulation. In addition, research by Nestler and colleagues has delineated molecular mechanisms underlying resilience to a social defeat stress paradigm in rodents, including the induction of gene expression changes only seen in resilient mice.
Neural Circuitries of Reward and Fear
Functional brain imaging studies in humans have demonstrated differential function of circuits involved in emotion regulation in several stress-related disorders, including major depression and posttraumatic stress disorder, compared to healthy controls. The fear and reward systems are two key and interrelated circuits of relevance to resilience. Yet, very little research on these circuits has been conducted in resilient individuals who have survived trauma exposure with relatively intact functioning.
“Well-functioning fear circuitry in resilient individuals, for example, might prevent over-generalization of fear responses to different contexts,” explains Dr. Feder. “This will only be clarified by studying individuals who have themselves survived an assault or a serious motor vehicle accident with few sustained symptoms.”
Another example involves reward circuit function. We now know from Fredrickson’s studies of positive emotion that the capacity to experience positive emotions in stressful contexts contributes to decreased autonomic reactivity.
“Positive emotions have also been linked to reward system function,” states Dr. Feder, “and brain imaging studies of reward circuitry function in resilient individuals are the next step.”
Conclusion
“Some of our understanding of resilience can be extrapolated from studies of individuals with depression and PTSD,” continues Dr. Feder, “but resilience is not just the opposite of vulnerability. In order to understand the unique mechanisms associated with resilience, we need more studies in people who have survived trauma and have adapted well. There is much to discover about the neurobiology underlying psychological traits characteristic of resilient individuals, with potential applications to prevention and treatment of stress-related psychiatric disorders.”
Disclosure: Dr. Feder has received grant support from the Department of Defense, GlaxoSmithKline, and the National Institutes of Health.
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