UCLA life scientists have identified for the first time a particlular gene's link to optimism, self-esteem and "mastery," the belief that one has control over one's own life - three critical psychological resources for coping well with stress and depression.
"I have been looking for this gene for a few years, and it is not the gene I expected," said Shelley E. Taylor, a distinguished professor of psychology at UCLA and senior author of the new research. "I knew there had to be a gene for these psychological resources."
The research is currently available in the online edition of the journal Proceedings of the National Academy of Sciences (PNAS) and will appear in a forthcoming print edition.
The gene Taylor and her colleagues identified is the oxytocin receptor gene (OXTR). Oxytocin is a hormone that increases in response to stress and is associated with good social skills such as empathy and enjoying the company of others.
"This study is, to the best of our knowledge, the first to report a gene associated with psychological resources," said lead study author Shimon Saphire-Bernstein, a doctoral student in psychology in Taylor's laboratory. "However, we wanted to go further and see if psychological resources explain why the OXTR gene is tied to depressive symptoms. We found that the effect of OXTR on depressive symptoms was fully explained by psychological resources."
At a particular location, the oxytocin receptor gene has two versions: an "A" (adenine) variant and a "G" (guanine) variant. Several studies have suggested that people with at least one "A" variant have an increased sensitivity to stress, poorer social skills and worse mental health outcomes.
The researchers found that people who have either two "A" nucleotides or one "A" and one "G" at this specific location on the oxytocin receptor gene have substantially lower levels of optimism, self-esteem and mastery and significantly higher levels of depressive symptoms than people with two "G" nucleotides.
The findings are "very strong, highly significant," Taylor said. The study has important implications.
"Sometimes people are skeptical that genes predict any kind of behavior or psychological state. I think we show conclusively that they do," said Taylor, who is a member of the National Academy of Sciences and directs UCLA's Social Neuroscience Laboratory.
She stresses, however, that while genes may predict behavior, the do not determine it.
Genes are not destiny
"Some people think genes are destiny, that if you have a specific gene, then you will have a particular outcome. That is definitely not the case," Taylor said. "This gene is one factor that influences psychological resources and depression, but there is plenty of room for environmental factors as well. A supportive childhood, good relationships, friends and even other genes also play a role in the development of psychological resources, and these factors also play a very substantial role in whether people become depressed.
"There is a genetic basis for these resources, but no - the OXTR gene does not explain most of these resources. The more you study genes, the more you realize that many factors influence their expression."
"The expression of genes is not always stable," Saphire-Bernstein noted. "For physical features like eye color, it is stable. Your eye color is not going to change this week, but your depression might change this week. Genes are only one set of contributing factors to behavior, to illness and to psychological disorders such as depression."
The researchers brought 326 people into a UCLA laboratory and had them complete self-assessments of optimism, self-esteem and mastery. To measure self-esteem, questionnaires included such statements as "I feel I am a person of worth, at least as much as other people" and asked subjects whether they agreed or disagreed, using a four-point scale. To measure optimism, the researchers included statements such as "In uncertain times, I usually expect the best" and "I hardly ever expect things to go my way."
The researchers obtained DNA from participants' saliva and used UCLA's Genotyping Center to analyze the DNA for the variants in the OXTR gene. Participants also completed an assessment of depression, using a tool that is often employed by clinical psychologists to identify people at risk for mental health problems.