Disease Model & Genetic Model of Substance Abuse

Instructor: Natalie Boyd

Natalie is a teacher and holds an MA in English Education and is in progress on her PhD in psychology.

Why do some people become addicted to drugs and alcohol, while others don't? In this lesson, we'll examine two theories that try to answer that question in terms of biology: the disease model and genetic model of substance abuse.

Substance Abuse

Yuri is worried about his twin brother, Franco. Franco drinks way too much, and can't control himself. He always says that he will stop, but he just can't seem to get it together.

Franco is suffering from alcoholism, a chronic addiction to alcohol. Alcoholism is a type of substance dependence which involves being dependent upon alcohol, or other drugs, for everyday functioning. People with substance abuse problems like Franco often struggle to stop using.

Yuri is curious about why Franco is the way that he is, and what causes his substance abuse. To help answer Yuri's questions, let's look at two theories about the cause of substance abuse: the disease model and the genetic model of addiction.

Disease Model

When Yuri goes looking for answers about why Franco is an addict, the first person he talks to tells him that he shouldn't be angry at Franco because addiction is a disease, like lupus or asthma.

The disease model of addiction, as its name suggests, looks at addiction as a physical disease. That is, it says that there are biological causes for substance dependence. The disease model of addiction has been around for over a century, however different ideas about the biological causes have changed throughout the years.

An article from 1904 supporting the disease model of alcoholism
Disease Model

These days, most proponents of the disease model believe that there are neurological causes for addiction. For example, perhaps Franco's brain has a different chemical or structural make-up compared to Yuri's. He may have less of a specific neurotransmitter, or one part of his brain might be smaller, like the frontal lobe. This region of the brain helps people consider consequences, and deals with impulse control. Both of which can have an affect on addiction, and may be the cause of Franco's alcoholism.

Like asthma, the disease model of addiction views substance dependence as an incurable disease. That is, doctors don't have a pill or injection to cure those with addiction. However, similar to asthma, substance dependance can be managed and treated. In the case of addiction, the disease can be treated with a combination of factors including therapy, 12-step programs, and sometimes prescription drugs.

Genetic Model

Yuri understands that his brother's addiction might be explained by biological causes, similar to asthma. But both Yuri and Franco have asthma. Does that mean that Yuri could become an addict too?

The genetic model of addiction attributes the cause of addiction to specific genes. This model shares certain characteristics like that of the disease model. Specifically, they both see biological causes as the underlying heart of addiction. In fact, like asthma, the genetic model sees addiction as a genetic disease, so it is very much linked to the disease model.

For centuries people have been aware that addiction can run in families. That is, parents who are addicts are more likely to have children who are addicts. But for a long time, scientists didn't know whether this was due to genetics being passed down, or whether it was a product of the addict's environment.

To understand the difference, let's look at Yuri and Franco. Their father was an alcoholic, just like Franco. So, did Franco inherit a gene from their father that made him an alcoholic? Or, did he become an alcoholic because he was raised in a home environment with an alcoholic father?

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