Substance Abuse and the Brain: What Happens Inside Your Mind When You’re Addicted?

We all like to picture our brains working at their sharpest, strongest and clearest. The thought of that power fading can be enough to fill us with dread, even when it happens naturally through old age.

But fewer people realise how profoundly addiction can disrupt the brain’s essential functioning. The most intricate organ in the body can become like an unlit labyrinth, which we struggle with daily.

What happens in the brain when you’re addicted?

There are physical changes that happen in the brain as addiction unfolds that highlight how addictions are not a matter of poor choices or weak willpower. Biological shifts in the brain’s structure show how its reward system is physically altered over time. Being at the mercy of an addiction makes a person strive to satisfy it, which changes the fundamental ways we experience pleasure, motivation and self-control.

At the centre of most of these changes is the neurotransmitter dopamine. This chemical is intrinsically related to how we feel pleasure and reward. Before an addiction forms, healthy activities like eating our favourite foods, socialising and hitting goals will release dopamine and gratify us. Addictive substances flood the brain with far more dopamine than natural rewards ever could, with some research suggesting as much as 10 times as much.

Over time, your brain gets used to “shortcutting” its way to deep pleasure. It starts producing less dopamine on its own and reduces the number of dopamine receptors. This is believed to lead to increased tolerance and the need to use more of a drug each time to achieve the same effect. Meanwhile, the previously mentioned natural sources of pleasure can be cast aside as drug or alcohol addiction unfolds.

How different substances hijack the brain

We’ve mentioned how an addictive substance can lay the foundation for manipulation in the brain’s chemistry. However, some substances can influence the brain’s functioning and impact neurotransmitters in different ways. These can include

• Alcohol and GABA/glutamate disruption: Alcohol increases the activity of GABA (gamma-aminobutyric acid), a neurotransmitter that calms brain activity while reducing glutamate, which typically excites the nervous system. This dual action slows down a lot of your physical functioning, including slurred speech, impaired judgement and sluggish reactions. Over time, the brain compensates by reducing GABA sensitivity and increasing glutamate, which is why withdrawal from alcohol can cause agitation, seizures and even delirium tremens.
• Stimulants and dopamine overload: Drugs like cocaine and methamphetamine cause a huge spike in dopamine, leading to intense feelings of euphoria, focus and energy. But, repeated use quickly depletes natural dopamine levels and desensitises the brain’s receptors. This leaves users unable to feel pleasure from everyday experiences and fuels a powerful drive to continue using just to feel “normal.”
• Opioids and pain/reward circuits: Opioids like heroin and prescription painkillers bind to the brain’s opioid receptors, dulling pain and triggering deep relaxation and euphoria. With continued use, the brain lowers its own natural production of endorphins (the body’s painkillers), making the person more sensitive to pain and emotional distress, conditions that further drive the addiction.

Addiction changes the brain over time

While the initial hijacking of the brain’s chemistry explains how addiction begins, the longer-term consequences are even more concerning. Continued substance use causes physical changes to the brain’s structure and function and can have catastrophic effects on a person’s daily life.

These changes include:

Addiction is a medical condition, not a “bad habit”

For too long, drug and alcohol addictions were viewed by the public and medical community as a moral failing, a sign of weak character, or a lack of willpower. Thankfully, the science behind addiction has grown clearer and we understand that addiction is a complex medical condition rooted in changes to brain chemistry and structure.

Brain imaging studies show how prolonged substance use alters the areas of the brain in control of judgement and motivation. The changes that happen here help to explain why someone may continue to use a substance, despite knowing the damage it’s causing.

By recognising and valuing addiction as a medical condition, we can stand in better stead to reduce the shame and stigma that so often keeps people from seeking help. It sets the stage for us to deliver compassion, not condemnation. With the right framing, an alcohol or drug addiction can be treated like other chronic illnesses, like diabetes or heart disease, with the right treatment and support.

How the brain heals in recovery

While addiction can significantly alter brain function, healing in recovery is possible. The brain is adaptable, and many of the changes caused by substance use can begin to reverse with sustained recovery.

Grey matter volume, often reduced during active drug addiction, can start to regenerate within months of sobriety. Cognitive functions like memory, focus and emotional regulation typically improve with time, especially when paired with therapy, exercise and healthy habits.

Recovery also helps restore balance to the brain’s reward system. Natural activities like connecting with others, mindfulness and physical activity can slowly replace the need for artificial highs.

Healing doesn’t happen overnight, but with consistency and support, your brain will start to rebuild, bringing back the purpose and drive you need for a stronger, healthier life.

I need help with an addiction in my life

If you or someone you love is struggling with addiction, know this: the brain can heal and recovery is possible.

At UKAT, we provide specialist addiction treatment designed to support both your body and your mind. Our programmes include medical detox, expert-led therapy and long-term aftercare to help rewire the patterns addiction has formed.

No one should have to fight addiction alone. Reach out to us today and take the first step towards healing, not just for your brain, but for your life.