Answer:
. Vulnerability to
develop an addiction to drugs is dependent on genetic, environmental, social and
biological factors. In particular, the interactions of environmental and genetic factors
indicate the significance of epigenetic mechanisms, which have been found to occur in
response to illicit drug use or as underlying factors in chronic substance abuse and
relapse. Epigenetics is defined as the heritable and possibly reversible modifications in
gene expression that do not involve alterations in the DNA sequence. This review
discusses the various types of epigenetic modifications and their relevance to drug
addiction to elucidate whether epigenetics is a predisposing factor, or a response to,
developing an addiction to drugs of abuse.