For a half-century, long-term studies of child development have shown that some people remain psychologically healthy even after years of severe deprivation and trauma. These findings surprised many clinicians, who tended to regard such experiences as overwhelmingly destructive. In response, some researchers have shifted their focus away from the causes of psychopathology and toward the characteristics and circumstances that buffer against stress.

Originally, some spoke of "invulnerable" children, but that suggested innate characteristics that shielded them against any kind of stress at any time. Instead, researchers now refer to "resilience," meaning the capacity to endure stress and bounce back — a capacity that may be available to a given person at some times and not others, under some threats and not others.

The first influences to be explored were psychological traits and social relationships. In early investigations of children who did well despite poverty, mentally ill parents, abuse, neglect, and community and family violence, researchers found that they were protected by — to quote an important review — "connections to competent and caring adults in the family and community, cognitive and self-regulation skills, positive views of self, and motivation to be effective in the environment."

Biological aspects

Investigators are trying to learn why and how resilient children develop these relationships, abilities, and attitudes. Adapting to stress is a complex process that involves many interacting influences. In the past, social and family environment have received most of the attention, but advances in genetics, psychopharmacology, and brain imaging permit closer study of the biological underpinnings of resilience.

An especially promising line of research involves the interaction between early experience and genetically determined neurobiology. Low levels of monoamine oxidase A (MAO-A), an enzyme that breaks down several neurotransmitters, have been linked to aggression in mice and humans. The gene that produces this enzyme has short and long forms, and the short form is less efficient. In a long-term study in New Zealand, maltreated boys with the short gene variant were, by age 26, much more likely than maltreated boys with the long variant to have committed violent crimes and to have high scores on a measure of aggressive tendencies — although neither maltreatment alone nor the gene variant alone raised these risks.

Other researchers have reported similar findings. For example, in a study of seven-year-old boys in England, both child abuse and low MAO-A activity independently raised the risk of all mental health problems (not just aggressive behavior). High MAO-A activity lowered the risk of mental health problems from child abuse.

A gene involved in synthesizing the neurotransmitter serotonin also exists in short and long variants, and the New Zealand researchers found that people with the long variant were less likely to become depressed when they were under stress. Monkeys also carry short and long variants of this gene. A study by researchers at the National Institute for Child Health and Human Development found that monkeys taken away from their mothers early in life (a highly stressful experience) were more aggressive and had defective serotonin balance — but only if they carried the short form of the gene. Monkeys who carried the long form were less aggressive no matter how they were reared.

High levels of another neurochemical, neuropeptide Y, may provide some protection against anxiety. People undergoing military survival training who had high levels of this substance performed better than those with lower levels, and combat veterans with post-traumatic stress disorder (PTSD) had lower levels than those who escaped PTSD.

If the neurochemicals are important, so is the efficiency of the brain circuits in which they operate. Brain imaging and other techniques permit researchers to look at cognitive and neuropsychological characteristics linked to resilience; for example, they can examine brain activity associated with working memory and executive function (problem-solving and planning).

Some researchers have become interested in how problems are solved by experts and people of high intelligence, as compared with lay people or those with lower intelligence. Studies have shown that, for example, the brains of experts are less active during relatively simple tasks, because they are working less hard to accomplish the same results. Brain imaging also suggests that in patients with PTSD, the hippocampus, a center for the consolidation of memories, is smaller than average. A person in whom this region is larger to begin with might be less vulnerable to the psychological effects of trauma.

Clinicians once were inclined to assume that resilience in traumatic situations, especially chronic trauma, was exceptional and required special explanations. They are coming to understand it as an especially effective form of normal adaptation — what one psychologist called "ordinary magic." Data are showing that most people can confront trauma and prevail (although differences between chronic severe stress and single acute traumatic experiences need to be explored).

Posttraumatic stress disorder is one sign that resilience has been exhausted. Researchers at Columbia University took advantage of a unique opportunity to observe people responding to overwhelming stress — the 2001 World Trade Center tragedy. About seven months after 9/11, and again after 18 and 28 months, they interviewed a sample of New York City area residents. The interviewees completed questionnaires and were classified into nine groups, including "lost job," "saw attacks in person from outside the World Trade Center," "involved in rescue and saw the attack," "friend or relative killed."

Even in the groups most intensely and intimately exposed to the attacks, at least a third were described as resilient, meaning that they had only one symptom or no symptoms of PTSD. And even in high-exposure groups, only a third developed PTSD. One characteristic associated with resilience was what the researchers call a tendency toward "self-enhancement," as indicated by very strong agreement with such statements as "I am fully in control of my own fate" and "I always know why I do things." In this study, resilient New Yorkers managed to live more or less normal lives, with minimal symptoms, throughout the aftermath of the attacks. They did not have to recover because they had not succumbed. Although they might have been upset or sad, they carried on.

The Columbia researchers concluded that not all survivors of such experiences need therapy or would benefit from it. Those who appear to be unaffected are not necessarily in denial. They may be able to reinforce resilience by performing familiar roles and maintaining familiar routines. Instead of venting feelings of anger and sadness, they benefit by recalling warm memories of a person who has died or appreciation of a community's cooperative response to a disaster.

Interest in resilience is also encouraged by the positive psychology movement, which has turned attention — in all circumstances, not just stress or trauma — away from pathology and toward strengths and virtues. That movement has also been concerned with the phenomenon of post-traumatic growth — a process through which suffering can give rise to compassion, wisdom, and well-being. Advocates of positive psychology judge that stress and trauma are as likely to stimulate as to impede adaptation and growth. Results from many fields of research may eventually lead to an understanding of resilience that suggests new ways to help people either resist or recover from the effects of stress and trauma.


Calhoun LS, et al, eds. The Handbook of Posttraumatic Growth: Research and Practice. Lawrence Erlbaum Associates, 2006.

Curtis WJ, et al. "Moving Research on Resilience into the 21st Century: Theoretical and Methodological Considerations in Examining the Biological Contributors to Resilience," Development and Psychopathology (Summer 2003): Vol. 15, No. 3, pp. 773–810.

Kim-Cohen J, et al. "MAOA, Maltreatment, and Gene-Environment Interaction Predicting Children's Mental Health: New Evidence and a Meta-Analysis," Molecular Psychiatry (October 2006): Vol. 11, No. 10, pp. 903–13.

Masten AS. "Ordinary Magic: Resilience Processes in Development," American Psychologist (March 2001): Vol. 56, No. 3, pp. 227–38.

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