In ASAM’s 2011 definition of addiction they write:
Addiction is a primary, chronic disease of brain reward, motivation, memory, and related circuitry. Dysfunction in these circuits leads to characteristic biological, psychological, social and spiritual manifestations. This is reflected in an individual pathologically pursuing reward and/or relief by substance use and other behaviors. Addiction also affects neurotransmission and interactions between cortical and hippocampal circuits and brain reward structures, such that the memory of previous exposures to rewards (such as food, sex, alcohol and other drugs) leads to a biological and behavioral engagement in addictive behaviors.
Redish, A. David, Steve Jensen, and Adam Johnson. “A Unified Framework for Addiction: Vulnerabilities in the Decision Process.” Behavioral and Brain Sciences 31.04, 2008. https://www.ncbi.nlm.nih.gov/pubmed/18662461