Parental neglect and abuse leave many children feeling hopeless and despondent. Yet some youngsters weather such maltreatment remarkably well. In a new study, scientists offer a rare peek at how genetics and interactions with adults collaborate either to depress mood or to foster resilience in abused kids.
Maltreated children who inherit two copies of a gene variant that was previously recognized to weaken the brain's mood regulation exhibit a marked propensity to become depressed only if they don't have a positive relationship with at least one adult, concludes a team led by psychiatrist Joan Kaufman of Yale University School of Medicine.
Kaufman's team studied 101 children, 57 of whom had been removed from their parents' care in the previous 6 months because of various types of abuse or domestic violence. The rest had no history of abuse and lived with their parents.
Saliva analyses showed that 42 of the kids possessed two copies of the full version of a gene that makes a protein critical to normal transmission of serotonin, a messenger chemical in the brain. Seventeen other children inherited two copies of a shortened version of this serotonin-transmitter gene, while another 42 had one copy of each version.
Children who hadn't been abused displayed few signs of depression, even if they had inherited only the short version of the gene. Depression symptoms were also rare among abused children with at least one copy of the longer version.
Depression scores were similarly low for abused kids with two copies of the short gene if they had maintained a positive relationship with an adult. However, abused children carrying only the short version of the gene showed a greater number of depression symptoms if there was no supportive adult in their lives, Kaufman and her coworkers report in the Dec. 7 Proceedings of the National Academy of Sciences.
"The quality and availability of social supports are among the most important environmental factors promoting resiliency in maltreated children, even in the presence of a gene expected to confer vulnerability to psychiatric disorders," Kaufman says. These findings underscore the pressing need for state agencies to find safe, permanent homes for abused children, she contends.
Even among children who weren't abused, adult support reduced their vulnerability to depression, regardless of the children's genetic makeup.
The study participants were 5 to 15 years old and included roughly equal numbers of boys and girls from a variety of ethnic and racial backgrounds. Children were interviewed about their relationships with adults, and both children and their parents filled out psychiatric questionnaires.
Another team, led by psychologist Avshalom Caspi of King's College London, reported last year that depressed adults who had been abused as children often possess two copies of the short serotonin-transporter variant.
A related study, directed by Christina S. Barr of the National Institutes of Health Animal Center in Poolesville, Md., finds that female monkeys raised in groups without their parents—a stressful situation for the animals—drink available alcohol to excess only if they also possess two copies of the short serotonin-transporter gene. Barr's report appears in the November Archives of General Psychiatry.
The new reports imply that "there aren't really genes 'for' psychiatric conditions," remarks Caspi. Instead, particular genes shape maladaptive or resilient responses by individuals to stressful circumstances, in his view.
Christina S. Barr
National Institutes of Health Animal Center
P.O. Box 529
Poolesville, MD 20837
Medical Research Council
Social, Genetic, and Developmental Psychiatry Research Centre
Institute of Psychiatry
King's College London
PO80 De Crespigny Park
London SE5 8AF
Department of Psychiatry
Yale University School of Medicine
New Haven, CT 06511
Bower, B. 2002. Resilient DNA: Gene may brighten future for abused kids. Science News 162(Aug. 3):68. Available to subscribers at [Go to].
Caspi, A., et al. 2003. Influence of life stress on depression: Moderation by a polymorphism in the 5-HTT gene. Science 301(July 18):386-389. Available at [Go to].