The Effect of Drug Addiction on Dopamine and the Brain Reward System

Drug Addiction on Dopamine


One of the questions that lie at the center of addiction research is this: why do people continue to use drugs even though it causes them problems for their health, finances, family, and even with the law? Addiction research has come a long way since, with strides in both psychology and neuroscience enabling scientists to have a much greater grasp of how addiction can affect the brain. The contemporary model of substance addiction has expanded to include a wide range of aspects including biological, psychological, and socio-cultural, which better inform the development of addiction treatment methods.

Understanding drug addiction isn’t merely a psychological one because drug addiction isn’t merely “in your head”. Drugs have biological and chemical effects on the brain, which is why addiction is so hard to kick! It isn’t just weak will or a lack of self-control because drugs literally rewire one’s brain to become dependent on them. It is hence crucial to understand also the brain and how it functions, and then see how drugs affect the brain functions. This article will focus on, in particular, the brain reward system and a chemical called dopamine which are impacted by the use of drugs.

How the Brain Works

The brain is responsible for ensuring that all bodily functions are carried out. To do this, the brain has a very complicated communication system that is carried out through electrochemical processes. Cells known as neurons make up the framework of this communication system by sending out electric pulses throughout the brain. Together, neurons make up the nervous system of the body and it manages the rest of the functions and parts by coordinating processes and activities in the body. These electric impulses are further controlled by neurotransmitters, chemicals that are secreted from the neurons. Neurotransmitters can either inhibit or activate the surrounding neurons, which absorb the neurotransmitters via a receptor. You can think of receptors and neurotransmitters as a lock and key, the receptor being the lock and the neurotransmitter as the key. The neurotransmitter will either activate the neuron to send another electric pulse or inhibit it from activating the next neuron.

The Brain’s Reward System

Our brains have evolved over human history in order to help us continually adapt and survive. One aspect of the survival system is the reward system. On a basic level, the brain rewards food and sex because these are crucial to survival as food is needed for energy and life, while sex is for procreation and the continuity of a family line. However, drugs can also work their way into this reward system. When the reward center of the brain activates, it releases a neurotransmitter called dopamine. Dopamine is responsible for a pleasurable and enjoyable feeling. From an evolutionary perspective, we continually engage in behaviors necessary for survival because they release dopamine and our brain is rewarding us for participating in these crucial activities. However, this same reward system is also how drug addiction begins. Drugs trigger the release of dopamine, which produces a pleasurable feeling and hence motivates us to repeat drug use because it feels good. All types of addictive drugs such as cocaine, heroin, and morphine, all release some level of dopamine into the body. Dopamine is often associated with “drug-seeking” behavior because it causes cravings for the drug.

What Happens When Someone Takes Drugs?

When someone first takes drugs, the pleasurable feeling dopamine produces is that quintessential “high: that they feel. Dopamine essentially unlocks the brain’s reward center, which is made up of the ventral tegmental area (VTA), nucleus accumbens, and substantia nigra (SN). However, as pleasurable as the first high can be for people, it is not what drives a sustained addiction. The novelty of someone’s first experience of being high soon wears off, and there are many other factors leading to a serious addiction forming. The next thing that happens is a psychological approach to the rewards system of the brain known as learning theory.

Learning theory explores how humans learn. One side of learning theory is known as operant conditioning and it is related to rewards and punishment. When a behavior is rewarded, one will increase the behavior. When there is a punishment associated with the behavior, it decreases. A substance can hence only be addictive if it is associated with rewards, such as pleasure or enjoyment. Addiction is hence a behavior that is learned as initial engagement in it was pleasurable or rewarding. Hence, someone who takes drugs and experiences the high will associate rewards with drug-taking. Drug addiction occurs because the person will actively seek out the drug to experience the brain’s reward response again.

Compulsive, continuous use of drugs occur because the person’s dopamine response lasts beyond the immediate activity of drug abuse. Natural reward behaviors like eating or having sex have an end to the dopamine release, but drugs do not. The intensity of dopamine is what keeps addicts coming back to the drug. Long-term usage of a drug also has an impact on the brain reward system and dopamine itself. The dopamine receptors will begin to decrease over time as it adjusts to the increased amount of dopamine in the brain. This decrease in dopamine will have a few effects on the brain. When there is this decrease in dopamine receptors, there will be impulsive behavior and increased self-administration of drugs due to the effect on the substantia nigra. The reduction in receptors also means that the person suffering from drug addiction will lose pleasure in other activities that they might have previously enjoyed. This state is also known as anhedonia. Anhedonia can cause depressive feelings that will also lead to a loss of control and impulsive decisions to take more drugs in order to feel pleasure and enjoyment again. Long-term drug abuse can also start to erode away the grey matter in the brain’s prefrontal cortex. The prefrontal cortex is responsible for our rational decision-making and ability to consider and evaluate various options. As a result, long-term drug abusers will lose their ability for rational thought and brain functioning.


Drugs have a very strong and sinister impact on our brains, by manipulating our brain reward system. Sometimes, pharmacological treatments are required for drug addiction as it is a chemical problem in the brain. Knowing this is key to developing an effective addiction recovery program. Do seek professional help if you suspect you might have a substance abuse problem.