The prominent 18th century American physician Benjamin Rush considered compulsive drinking a loss of self-control on the part of the drinker. This view toward addiction influenced many of the early modern approaches to prevention and treatment. However, with the advent of brain science, the last few decades have ushered in a new way of thinking about addiction: as a chronic but treatable disease.
Addiction as a Disease
Many people initially resist the idea as a chronic disease, remaining convinced that the problem lies with a person’s poor willpower or loss of self-control. While it is true that a person may 
choose to use drugs or alcohol, powerful biological mechanisms make it more likely that some people will struggle to control their use.
In this way, addiction is akin to other chronic medical conditions such as cardiovascular disease. The choices people make — eating fatty foods, not getting enough exercising, being under high stress — increase the likelihood of having cardiovascular disease. However, the disease occurs because of biological processes that are influenced by genetics and individual differences in physiology.
Biological Contributors to Drug Addiction
Addiction is a complex and multifactorial illness. There is not one single variable that causes your loved one to struggle with addiction while other family members do not. Scientists are still unraveling the biological mechanisms underlying addiction, but some factors include:
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Genetics
According to the National Institute on Drug Abuse, between 40 and 60% of an individual’s likelihood to become addicted can be attributed to genetic factors. In fact, many people struggling with addiction can identify family members who have also suffered from substance abuse. Scientists have isolated several genetic risk factors that are more common among drug users; however, there is no current way to change genetic risk.
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Gender
Overall, more men than women use drugs and experience addiction. Whether this is due to social factors or underlying biological factors is unclear. However, it is likely to be a mixture of both.
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Brain structure and chemistry
When a person first takes a drug, the drug travels into the brain and affects its reward system. This triggers intense feelings of pleasure, causing the brain to tell the person,
“I want more of that!” Certain individuals may be predisposed to have more sensitive reward systems. Thus, when those people begin using drugs, their brains may be primed to experience the drug use very positively. These differences in brain structure and levels of certain brain chemicals make those people more vulnerable to addiction -
Vulnerability to mental health problems
Addiction and other mental health issues seem to hang together, with an estimated 8.9 million Americans experiencing both problems, according to the Substance Abuse and Mental Health Services Administration. Although the exact mechanisms are unclear, having conditions such as depression, anxiety disorders, schizophrenia, or bipolar disorder appear to make people more vulnerable to drug use and addiction.
How Our Understanding of Drug Addiction Informs Treatment
We now know that addiction is a chronic disease that results from biological factors such as differences in brain chemistry. However, addiction is not a life sentence. Researchers have found several forms of treatment that help people overcome this chronic illness.
For example, medically supervised detox, medication management, and psychotherapy are important components of effective treatment. Recognizing that addiction is a treatable, manageable condition is the first step in ensuring that your loved one gets help.
Resources:
- Crocg, M-A. (2007). Historical and cultural aspects of man’s relationship with addictive drugs. Dialogues in Clinical Neuroscience, 9(4), 355-361. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3202501/
- National Institute on Drug Abuse. Drug abuse and addiction. Drugs, Brains, and Behavior: The Science of Addiction. July 2014. http://www.drugabuse.gov/publications/drugs-brains-behavior-science-addiction/drug-abuse-addiction
- Substance Abuse and Mental Health Services Administration. Rates of co-occurring mental and substance use disorders. Co-occurring Disorders. http://media.samhsa.gov/co-occurring/topics/data/disorders.aspx