Adults who had been abused but didn’t have the variations in the gene had twice the symptoms of moderate to severe depression, compared to those with the protective variations. “Knowing what those variations are eventually could help clinicians individualize care for their patients by predicting who may be at risk or suggesting more precise avenues for treatment”, said NIMH Director Thomas R. Insel, M.D. Almost 15 million U.S. adults have major depression. The new report adds to evidence that a combination of gene variations and life experiences promote the disorder or protect people from it. Variations in many genes are thought to be involved, but few of them have been identified.
The study also supports previous evidence that a stress hormone, corticotropin-releasing hormone (CRH), plays a role in depression. CRH and its receptor are part of a larger hormone system that regulates the response to stress, in part by helping to regulate neurotransmission – the chemical messages through which brain cells communicate with each other. Extreme stress in childhood caused by factors such as abuse can hyperactivate the system, increasing risk of depression in adulthood.
To conduct their research, scientists interviewed 422 adults, mostly African American, and tested their DNA. About one-third of them had the variations in the CRHR1 gene that appear to be somewhat protective if early-life stress has occurred. The finding was strengthened when the researchers repeated the study in 199 white adults and came up with similar results. In addition to racial differences, the two groups differed socioeconomically. The combined findings suggest that the gene variations are protective across the ethnic groups and socioeconomic levels.
MEDICA.de; Source: National Institute of Mental Health