How Do Opioids Rewire the Brain?

How Opioids Work in the Brain

Opioids work by attaching to opioid receptors in the brain and other parts of the body. These receptors help regulate pain, reward and other important functions.

When an opioid activates these receptors, it can reduce the intensity of pain signals. Opioids can also affect reward and reinforcement pathways, which is one reason repeated use can become strongly motivating for some people.

Opioids also influence brain systems involved in breathing. At high enough exposure—especially during an overdose—breathing can become dangerously slow or stop completely.

Immediate Effects vs. Brain Adaptation Over Time

The immediate effects of an opioid are not the same thing as the longer-term changes associated with repeated exposure.

Immediate effects can include pain relief, sedation, euphoria and slowed breathing.

Tolerance means that repeated exposure can reduce the effect produced by the same amount of a drug.

Physical dependence means the body has adapted to ongoing exposure and may develop withdrawal symptoms if the opioid is stopped.

Opioid use disorder is a clinical condition involving a problematic pattern of opioid use and is not defined simply by tolerance or physical dependence.

Repeated opioid exposure does not “rewire” every person’s brain in an identical or permanent way. The effects vary with the opioid, dose, frequency, duration of exposure, genetics, health, environment and other factors.

Buprenorphine Works Differently From Full Opioid Agonists

Buprenorphine is also an opioid medication, but its pharmacologic profile differs from full opioid agonists such as fentanyl or heroin. It can be used as part of evidence-based treatment for opioid use disorder when prescribed and monitored appropriately.

For the medication-specific distinction, read Recovery Care of Columbia’s guide to buprenorphine, dependence and addiction.

If you’re addicted to opioids, then you already know the feelings of constant cravings, much like the song Constant Craving by K.D. Lang.

Various studies have been conducted, hoping to find the reason that some people seem to get addicted to opioids more easily than others.

Do Some People Get Addicted to Opioids More Easily?

Yes, absolutely. Opioid addiction doesn’t affect everyone equally, and some individuals are definitely more prone to developing a dependence on these drugs than others. This is due to a complex interplay of factors, but here are some of the key reasons why some people might get addicted more easily:   

1. Flooding the Reward Circuit:

• Dopamine surge: Opioids bind to opioid receptors in the brain, particularly in the ventral tegmental area (VTA) and nucleus accumbens, key areas of the reward circuit. This triggers a massive release of dopamine, a neurotransmitter associated with pleasure and motivation. The dopamine surge caused by opioids is far more intense and longer-lasting than those produced by natural rewards like food or sex.
• Reinforcing drug use: This intense pleasure reinforces the act of taking opioids, making the brain “learn” that opioid use is highly desirable and should be repeated. This is a crucial step in the development of addiction.

2. Changing Brain Chemistry and Structure:

• Reduced dopamine production: Over time, the brain adapts to the constant flood of dopamine caused by opioids. It becomes less sensitive to dopamine and starts producing less of it naturally. This leads to dependence, where a person needs opioids just to feel “normal” and avoid withdrawal symptoms.
• Altered brain circuitry: Chronic opioid use can lead to changes in the brain’s structure and function, particularly in areas related to decision-making, impulse control, and stress response. This can make it harder for individuals to resist cravings and make sound choices.

3. Creating a Cycle of Dependence:

• Tolerance: As the brain adapts, users need to take higher and higher doses of opioids to achieve the same effect. This is known as tolerance.
• Withdrawal: When opioid use is stopped or reduced, the brain experiences a sharp drop in dopamine and other neurochemicals, leading to withdrawal symptoms. These can be extremely unpleasant, including intense cravings, anxiety, muscle aches, vomiting, and diarrhea.
• Relapse: The intense discomfort of withdrawal and the powerful cravings drive many people to relapse, perpetuating the cycle of addiction.

Opioids hijack the brain’s reward system, altering its chemistry and structure to create a powerful dependence on the drug. This makes it challenging for individuals to overcome opioid addiction without professional help.