People feel pleasure when basic needs such as hunger, thirst and sex are satisfied. In most cases, these feelings of pleasure are caused by the release of certain chemicals in the brain, which reinforce these life-sustaining functions by incentivizing the individual to repeat the behaviors that produce those rewarding feelings (eating, drinking and procreating). Most addictive substances cause the brain to release high levels of these same chemicals that are associated with natural pleasure or reward.

Over time, continued release of these chemicals causes changes in the brain systems involved in reward, motivation and memory. The brain tries to get back to a balanced state by minimizing its reaction to those rewarding chemicals or releasing stress hormones. As a result, a person may need to use increasing amounts of the substance just to feel closer to normal. The individual may experience intense desires or cravings for the substance and will continue to use it despite harmful or dangerous consequences. The person may also prefer the substance to other healthy pleasures and may lose interest in normal life activities. In the most chronic form of the disease, a severe substance use disorder can cause a person to stop caring about their own or others’ well-being or survival.

These changes in the brain can remain for a long time, even after the person stops using substances. It is believed that these changes may leave those with addiction vulnerable to physical and environmental cues that they associate with substance use, also known as triggers, which can increase their risk of relapse.

The initial and early decisions to use substances are based in large part on a person’s free or conscious choice, often influenced by their culture and environment. Certain factors, such as a family history of addiction, trauma or inadequately treated mental health disorders such as depression and anxiety, may make some people more susceptible to substance use disorders than others. Once the brain has been changed by addiction, that choice or willpower becomes impaired. Perhaps the most defining symptom of addiction is a loss of control over substance use.

People do not choose how their brain and body respond to substances, which is why people with addiction cannot control their use while others can. People with addiction can still stop using substances — it’s just much harder than it is for someone who has not become addicted. People with addiction should not be blamed for having a disease, but rather be able to get quality, evidence-based care to address it.

With the help and support of family, friends and peers to stay in treatment, they increase their chances of recovery and survival.

A chronic disease is a long-lasting condition that can be controlled but not cured.

Most people who engage in substance use do not develop addiction. And many people who do so to a problematic extent, such as young people during their high school or college years, tend to reduce their use once they take on more adult responsibilities. Still, about 25-50% of people with a substance use problem develop a severe, chronic disorder. For them, addiction is a progressive, relapsing disease that requires intensive treatments and continuing aftercare, monitoring and family or peer support to manage their recovery.

The good news is that even the most severe, chronic form of the disorder can be manageable, usually with long-term treatment and continued monitoring and support for recovery.

Some people think addiction cannot be a disease because it is caused by the individual’s choice to use substances. While the first use (or early stage use) may be by choice, once the brain has been changed by addiction, most experts believe that the person loses control of their behavior.

Choice does not determine whether something is a disease. Heart disease, diabetes and some forms of cancer involve personal choices like diet, exercise, sun exposure, etc. A disease is what happens in the body as a result of those choices.

Others argue that addiction is not a disease because some people with addiction get better without treatment. People with a mild substance use disorder may recover with little or no treatment. People with the most serious form of addiction usually need intensive treatment followed by lifelong management of the disease. However, some people with severe addiction stop drinking or using other substances without treatment, usually after experiencing a serious family, social, occupational, physical or spiritual crisis. Others achieve recovery by attending self-help (12-step or AA) meetings without receiving much, if any, professional treatment. In all cases, professional treatment and a range of recovery supports should be available and accessible to anybody who develops a substance use disorder. Addiction is a treatable disease.