Long-term Consequences of Drug Use on the Brain

Your brain is the most complex organ in your body, weighing in around three pounds and made up of white and gray matter that serve as the source of all of the qualities that make you human.

Different parts of the brain serve different functions, and they all work together to coordinate specific actions, from interpreting marks on paper into language and information to tasting the donut you had for breakfast. Because drugs affect the mind, it can have negative effects on the brain. Here we explain the long-term consequences of drug use.

Areas of the Brain Affected by Drugs

Drugs alter your brain by affecting the following structures:

  • The brain stem, which controls basic functions like breathing and heart rate
  • The cerebral cortex, which processes information from our senses and houses the thinking center of the brain that enables us to solve problems and make decisions
  • The limbic system, which contains the brain’s reward circuit that controls our ability to feel pleasure, enables us to perceive emotions and motivates us to do things like socialize, exercise and eat—things that are essential to our existence.

To understand how drugs affect your brain, it’s critical to understand how the brain communicates with itself.

The Communications Center: A Primer

Your brain contains billions and billions of nerve cells known as neurons. Groups of neurons send and receive messages to and from the various brain structures, the spinal cord and the body’s complex system of nerves. These messages contain instructions for virtually everything we do: scratch an itch, create art, or experience emotions.

The messages are sent and received as chemical and electrical signals that are carried by chemicals called neurotransmitters. A neurotransmitter is like a key, and it fits perfectly into the receiving neuron’s receptor, which is like a lock. Once the message is received, a transporter located on the neuron that sent the message takes the neurotransmitter back, shutting off the signal between the neurons.

Introducing… Drugs

The National Institute on Drug Abuse explains that drugs interfere with the way neurons send and receive messages.1 The chemical structure of drugs like heroin and marijuana mimics the structure of a neurotransmitter and fools the receptors into letting the drug activate the neuron, but they don’t activate it in the same way natural neurotransmitters do; instead, abnormal messages get sent through the neuron networks.

Other drugs, like cocaine and meth, cause the release of abnormally large amounts of a neurotransmitter. In some cases, they prevent the brain from recycling the neurotransmitter. This causes a disruption in the brain’s communication protocol.

Dopamine and the Reward System

Most psychoactive drugs act on the brain’s reward system. They flood the circuits with dopamine, the neurotransmitter responsible for movement, motivation, emotion and feelings of pleasure. Under normal, natural circumstances, this system rewards behaviors like eating when we’re hungry so that we’ll stay alive and having sex so that we’ll procreate.

Each time we do something that’s pleasurable, the brain takes copious notes and teaches us to do it again and again—keep eating, keep having sex. When this system is overstimulated—some drugs release up to 10 times the amount of dopamine that rewards us for normal activities—we feel an incredible sense of euphoria and wellbeing, and the brain again takes notes and teaches us to crave that behavior again and again

How the Brain Compensates for Drugs: The Building Up of Tolerance

When you chronically abuse a drug, the brain compensates for the abnormally high surge of neurotransmitters by either reducing its production of those neurotransmitters or by reducing the number of receptors that will accept the message. This reduces the drug’s ability to produce the pleasure the user has come to expect. In response, the user increases the amount of the drug. This is how you build up a tolerance to a drug.

At the same time, the reduction of neurotransmitters leads to the inability to feel pleasure without the drug, which reinforces the drug-taking behaviors. Eventually, you may develop an addiction, which is characterized by the inability to control your drug use, poor decision making and intense, uncontrollable cravings for the drug of choice.

How Tolerance Leads to Dependence

The more drugs you take to compensate for the brain’s adjustment to the drug, the more the brain will continue to counteract, and eventually, this will lead to profound changes in its structures and functions. When the tipping point is reached, your brain will need the drug to operate “normally.”

When the drug is withheld, the now-suppressed or overactive neurotransmitters will rebound, and you’ll experience withdrawal symptoms. Withdrawal symptoms are an indication that you have developed a dependence on the drug.

Long-Term Effects of Drugs on the Brain

Long-term drug abuse leads to serious, long-lasting consequences for the brain, according to the National Institutes of Health.1 Drugs like alcohol and MDMA kill neurons, which can lead to impaired memory, problems with thinking and processing information and changes in functions like sleep patterns and appetite. Drugs like cocaine reduce the activity level of neurons for the long-term, making it difficult to feel pleasure, which is why depression is a common withdrawal symptom that can persist for far longer than other withdrawal symptoms.

Regardless of the substance, drugs almost always worsen a mental illness, and they can even cause the onset of symptoms of a mental illness, such as depression or anxiety. Other long-term effects of drugs on the brain include the inability to appropriately cope with stress, trouble with decision-making and emotional problems. Click here to contact us for help.

Restoring Brain Function

Detox is the first step of professional drug treatment, and it breaks the physical dependence on drugs by withholding the drug so that traces can be flushed from the brain and brain function can begin to return to normal. But detox generally isn’t enough to end an addiction. Doing so requires intensive therapy that helps you consciously change your way of thinking and work through the issues that led you to abuse drugs in the first place.

While some of the effects of drugs on the brain may never be completely reversed, the sooner you get help for chronic drug abuse or addiction, the sooner your brain function can return to normal and healing can begin.


  1. http://www.drugabuse.gov/publications/drugs-brains-behavior-science-addiction/drugs-brain
  1. Long-term drug and alcohol abuse can have disastrous physical and mental health consequences. As the body adapts to the presence of a substance, it requires increasing amounts of it to experience the desired results, a process known as tolerance. As a user continues to increase doses, physical dependence may develop, which may subsequently give rise to unpleasant and sometimes deadly withdrawal symptoms once the person stops using the substance.

    • And during this tolerance the amounts of dopamine that are artificially released due to use slowly begins to burn out and not produce as much and the receptors tend to burn out as well which can then cause serious mood and behaivor disorders.

  2. Beth D'Angelo says:

    I was addicted to drugs and alcohol for 34 years. My addiction started with alcohol, I added cocaine, pain pills, xanex and finally ended my addiction injecting heroin and meth. 2015 was one of the worst and best years for me. My brother died of a heroin in overdose in February. I overdosed twice that year and finally went to treatment in December. After 92 days in treatment I entered a faith based recovery program where I lived for two years. I was raised by a drug addicted mother and because I did not know better I also raised three of my four children in the madness of addiction. I am happy to say that all 3 of my children are now in recovery. I met and married my husband who is in recovery from heroin as well.

    I am writing today because I have had this continual ringing sound in my brain since I detoxed. A doctor friend of mind who works with recovering addicts believes the noise is from long term drug addiction. I have noticed that when I become emotional the noise becomes louder also during my period its almost unbearable. Do you know of others in recovery that suffer with this ringing noise?

    • Congratulations on your long term sobriety. Thank you for sharing a piece of your story with us. I haven’t heard much about the continuous ringing noise with others in recovery, but cannot rule out that the abuse that our brains and bodies took could result in such a phenomenom.

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  4. Jillian smith says:

    I am 66 years old. I have bipolar disorder. I was introduced to crack cocaine approx 8 years ago. The effects were better than that of my prescribed meds. Does this seem “average” for those who suffer with bipolar? I also have short term memory issues. Family lineage is; grandmother with dementia and mother with full blown alzheimers. Am i causing more damage to my brain function than bipolar alone?

  5. Great advice on how you should not underestimate the effects of drugs since it affects your brain’s dopamine reward system. I learned that my colleague has been demotivated at work recently and I want to help him get back on his feet. I’ll suggest getting treatment for substance abuse if necessary.

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