Our brains are hardwired to seek pleasure and avoid danger. It’s what helps the human species survive. Biting into something luscious, enjoying a passionate kiss, or delighting in a baby’s laugh lights up the brain’s pleasure centers. Negative experiences set off fear and alarm.     

Addictive drugs can “hijack the brain’s reward system,” says Andrew Kolodny, M.D., a senior scientist at Brandeis University and chief medical officer at Phoenix House, a national nonprofit center for addiction treatment. “They can overstimulate the brain’s reward centers and also inhibit the part of the brain that reacts to potential harm.”

It’s a cruel trick. Over time, the brain changes: overstimulated pleasure circuits start shutting down, causing people to feel joyless, anxious, and depressed. Eventually they “are no longer using to feel good but to avoid feeling horrible,” Kolodny says.

In addition, repeated exposure to the addictive substance can damage the brain’s frontal cortex, where decision-making takes place—paradoxically, the part of the brain involved in helping people recognize and control harmful behavior.

Who's at Risk

You’re at greater risk for addiction if you’ve had anxiety, depression, or other mental health disorders or if you or a close family member has a history of substance abuse. But almost anyone can become addicted with the repeated use of a highly addictive drug. 

Opioids, including prescription painkillers such as OxyContinPercocet, or Vicodin are highly addictive. As many as one out of four people taking a prescribed opioid for several months or longer becomes addicted according to the Centers for Disease Control and Prevention (CDC)—even if taking it legitimately to combat pain.

Problems with overuse aren't limited to opioids. Almost one out of five marijuana users has a substance-use disorder, indicating that the drug is causing health problems or interfering with daily life according to a 2014 government survey.    

Avoid the Addiction Trap

If your behavior is harmful or impacting your quality of life (or others tell you that it is) and you are unable to stop, talk to your doctor. He or she can help you regain control, or refer you to a healthcare professional who specializes in substance abuse disorders.

The key to minimizing the risk of opioid addiction is to not take a the drugs longer term, according to the CDC. If you need a prescription to treat severe short-term pain, the CDC recommends a short course—three day's worth is typically sufficient. For persistent pain, talk to your doctor about other types of pain medication and nondrug measures that can provide just as much or more relief than an opioid with less risk. If you wind up taking an opioid for chronic pain, the CDC advises starting at the lowest effective dose and checking in with your doctor regularly to make sure that the drug is helping and that you are able to take it safely.

Read more on the latest advice from the CDC on using opioids to treat chronic pain.

Editor's Note: This article and related materials are made possible by a grant from the state Attorney General Consumer and Prescriber Education Grant Program, which is funded by the multistate settlement of consumer-fraud claims regarding the marketing of the prescription drug Neurontin (gabapentin).

This article also appeared in the June 2016 issue of Consumer Reports magazine.