Substance dependence: Overview of the environmental, genetic, epigenetic, and imaging studies

Abstract

A complex condition like substance dependence (SD) causes disruption in brain circuits leading to various health issues and conditions like homelessness, crime, and violence. Environmental factors play an important role in substance dependence and genetic causes add to the susceptibility of individuals to these disruptions, thereby leading to dependence. Several studies based on twin pairs, families, and adoption point to the involvement of genetics in substance dependence. Besides genetics, there is evidence highlighting the importance of epigenetic modifications of genes leading to neuroplastic changes in the brain of individuals with substance dependence. Brain imaging techniques like positron emission tomography/single-photon emission computed tomography (PET/SPECT) can be helpful in the identification of neuroadaptive and neurodegenerative changes which in the future may help in the development of pharmacological treatment targets for SD. The progress made in the field of genetics, epigenetics, and imaging in substance dependence and their applications, along with genes whose polymorphisms and methylation status may evolve as potential biomarkers in substance dependence, is highlighted here.