Registered Nurses' Association of Ontario

Addiction/Substance Dependence Definition

  • Addiction is a result of a complex interaction of factors with no distinct single cause. It is not the result of a character flaw, personal choice or weakness (Centre for Addiction and Mental Health, 2008c).  Addiction and substance dependence are characterized by the compulsive and continued misuse of a substance, despite its overtly negative consequences
  • Multiple factors that can influence additions include: Genetics, brain physiology, physical and mental illness, complex trauma, posttraumatic stress disorder, stress, street culture, and a history of childhood abuse. These factors are often compounded by other social determinants of health (i.e. homelessness, unemployment, and poverty).
  • Addiction can present as a combined psychological and physiological dependence (opioid) or solely as a psychological dependence (cocaine) disorder.
  1. Physical dependence occurs when a person’s body has developed a tolerance to the drug so that more is needed to achieve the same effect (often includes feeling “normal”). This may include the presence of withdrawal symptoms if there is a sudden discontinuation of drug.
  2. Psychological dependence occurs when the pattern of compulsive drug use is characterized by a continued craving for a drug and the need to take it due to the feelings of well-being that the drug produces.
Addiction and Mental Health
Supporting Clients on Methadone Maintenance Treatment
Background Information