Using Neuroscience to
Explain How Drugs and
Alcohol Affect the Brain

Opioids Bond to Opioid Receptors

An opioid is a drug derived from or synthesized from a poppy plant. Opioids come in a variety of forms, including as the active ingredient in many commercial pain relievers, and in street drugs like heroin and fentanyl. Essentially, opioids take effect by mimicking molecules found naturally in the body.

In the brain, there are sites located on nerve cells, called opioid receptors. Our body naturally produces opioid peptides that stimulate these sites to regulate pleasure and pain. The problem is that molecules found in opioid drugs are similar in structure to the body’s natural opioid peptides.

These molecules bind to opioid receptors, triggering a rush of dopamine, a chemical that accompanies feelings of pleasure and euphoria. Opioids are unique in the way that they cause dependence very quickly — the user essentially has to use more and more each time to get the same effect, because the brain develops a tolerance to this heightened level of dopamine.

This is the reason for opioids’ notoriously severe withdrawal period: when a person tries to stop using these drugs, the brain and body don’t know how to react and cause harsh and uncomfortable symptoms to set in.

Alcohol & Benzos Affect GABA Response

While creating similar effects, substances like alcohol and benzodiazepines (often shortened to “benzos”) hijack a different process in the brain. It starts with gamma-aminobutyric acid (GABA) receptors, nervous sites that cause slowed reaction times and decreased inhibitions when interacted with.

The unique chemical structures of alcohol and benzos allow it to bind to GABA receptors and create these depressant effects in the brain, along with a general feeling of calm and pleasure. Similar to the euphoric feelings produced by opioids, the calmness caused by these benzos and alcohol is a feeling that, when used repeatedly, is adopted into the central nervous system’s reward center.

The brain starts to rely on this reaction to function, and once it stops receiving the substance in question, it causes the body to go into withdrawal.

MDMA’s Unnatural Release of Serotonin

MDMA, one of a group of “club drugs”, is a type of stimulating amphetamine that became popular in the 1980s and persists to this day. Studies on MDMA are also less common than ones pertaining to, say, alcohol, because of its status as an illegal drug.

That said, what we can talk about is the way it interacts with the brain. In many amphetamines, and particularly with MDMA, the drug binds to transporter proteins for certain chemicals, and releases serotonin, dopamine and norepinephrine, causing that “high” feeling. Of those three, the most heavily released is serotonin. So much of it is released, that the brain can feel depleted after the presence of the drug has run out.

Serotonin is a mood regulator in the brain, and this shortage is what makes someone’s “low” feelings become so much lower when they come down from MDMA and show symptoms of depression.