Early life substance abuse and epigenetic programming

The vulnerability to substance use disorders (SUDs) is reliant on genetic, environmental, and social factors. The interaction of environmental and genetic factors, particularly epigenetic mechanisms, has recently gained attention as a potent contributor to the development of SUDs. Epigenetic modifications are defined as heritable changes in gene expression not caused by alterations in the DNA sequence. Recent evidence has shown that abused substances, including alcohol, nicotine, cocaine, and marijuana, have profound effects on gene expression, which can persist over long periods of time. Interestingly, both maternal and paternal drug use prior to conception, as well as prenatal drug exposure, has been shown to alter gene expression in offspring and can predispose to future drug use. Epigenetic modifications are also induced following adolescent and adult drug use. This chapter highlights the various types of epigenetic modifications induced by abused substances and the effects of these modifications on future vulnerability to SUDs.