Newswise — Exposure to adversity as a child can affect how the body responds to stress, and may increase the risk of negative health behaviors and addictions in adulthood. However, the impact of early life adversity may depend partly on an individual’s genetic makeup. The ‘COMT’ gene is of particular interest ─it occurs in two common variant forms, MET and VAL, that differentially affect key molecules involved in the human stress response, and these gene variants may also influence vulnerability to our early environment.
Researchers from the Family Health Patterns Project investigated the impact of childhood exposure to physical, sexual, and emotional adversity in 480 healthy young adults who inherited either the MET or VAL genotypes and who described their histories of alcohol and recreational drug use. The researchers then measured the stress hormone, cortisol, in saliva samples from the volunteers during a series of public speaking and mental arithmetic challenges.
Volunteers inheriting the COMT MET genotype who were exposed to childhood adversity had an abnormally blunted cortisol response to stress. These same persons also reported taking their first drink before the age of 15 and experimenting with more types of recreational drugs than the other groups. Previous research shows that alcohol use before age 15 and having a diminished response to stress are both predictors of future alcohol dependence.
People who inherit the MET form of the COMT gene are sensitive to their early environment, with implications for addiction risk. This combination of a gene and environment leads to a blunted cortisol stress response and also to early experimentation with alcohol and drugs. Blunted reactivity and early experimentation are both predictors of risk for alcoholism. Although further research is needed, these findings reinforce the impact of early life experience on the body’s response to stress and on risky drinking and drug-use behaviors in people with genetic vulnerabilities.
Early life adversity and blunted stress reactivity as predictors of alcohol and drug use in persons with COMT (rs4680) Val158Met genotypes