Dr. Mary Anne Kowal is an addiction specialist at Froedtert and the Medical College of Wisconsin. She says Wisconsin's heroin and opioid problem is "at an epidemic level."

She says that many addicts can stay clean for months or years, doing everything right, "however they're still very vulnerable if they're exposed to the original substance or to a new habit-forming substance."

Listen to the full conversation between Dr. Kowal and WTMJ's John Mercure and Erik Bilstad.

Addiction Specialist Dr. Mary Anne Kowal says addictions cause changes in the brain

WTMJ