The American Society of Addiction Medicine (ASAM), the largest professional society of doctors dedicated to treating and preventing addiction, has released a new definition of addiction, calling it a chronic brain disorder, not just a behavior problem, USA Today reports. The medical group announced the new definition after a four-year process that involved more than 80 experts.

“At its core, addiction isn’t just a social problem or a moral problem or a criminal problem. It’s a brain problem whose behaviors manifest in all these other areas,” Dr. Michael Miller, Past President of ASAM, who oversaw the development of the new definition, said in a news release. “Many behaviors driven by addiction are real problems and sometimes criminal acts. But the disease is about brains, not drugs. It’s about underlying neurology, not outward actions.”

This marks the first time ASAM has taken an official position that addiction is not simply related to substance abuse. The group said outward behaviors of substance abuse are manifestations of underlying disease that involve different parts of the brain. According to the new definition, addiction is a primary disease, not the result of other causes such as psychiatric problems. ASAM notes addiction is chronic and must be managed throughout a person’s lifetime.

Dr. Raju Hajela, Past President of the Canadian Society of Addiction Medicine, who chaired the ASAM committee that came up with the new definition, said addiction is not a choice. “The disease creates distortions in thinking, feelings and perceptions, which drive people to behave in ways that are not understandable to others around them.”

Dr. Nora Volkow, Director of the National Institute on Drug Abuse (NIDA), told USA Today the new definition will help her agency convince more primary care doctors to screen patients for signs of addiction. According to NIDA, 23 million Americans need substance abuse treatment, but only two million receive it.