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The Science Behind Addiction; How does it change the Human Brain?

Updated on May 9, 2013
A pipe and lighter associated with an addiction to crack cocaine
A pipe and lighter associated with an addiction to crack cocaine

So what exactly is drug addiction?

An addiction in its simplest definition is a chronic, relapsing brain disease. An addict has a compulsive need to seek drugs, despite the harmful effects on themselves and those around them. Modern science and research has determined that an addiction is a brain disease. Though, there are many people that argue this. The brain structure and how it functions is changed because of the addiction, therefore it can be categorized as a brain disease.

representation of the human brain and drug effects
representation of the human brain and drug effects | Source

How does the brain normally communicate?

The human brain is packed full of nerve cells. These nerve cells, also called neurons pass messages back and forth in the form of electrical impulses. The neurotransmitters are the actual structures that carry these messages. Receptors are the portion of these nerve cells that receive the massage. If the neurotransmitter was a key, the corresponding receptor would be the lock. The transporters are the portion of the nerve cells that take in the neurotransmitters and recycle them. This entire network is responsible for the way we feel, how we think and what we do. Without this communication network, the human body would not know what to do with itself.

How do drugs affect the brain?

Drugs are chemicals that are taken into the body. There are many forms and multiple levels of effects, but essentially they all do the same things. They corrupt the brain’s natural communication system and change the way nerve cells function. These nerve cells are crippled. The way they normally send, receive and interpret information is then changed.

There are two distinct ways that drugs change these nerve cells. Certain drugs will activate neurons in the brain because their chemical structure mimics the natural neurotransmitter. Though it is similar, it is still not the same as these natural neurotransmitters. Therefore, the drugs cause abnormal signals to be sent around the entire brain. The other way that nerve cells are affected is by forcing nerve cells to release large amounts of natural neurotransmitters and prevent the normal recycling of these brain chemicals. The brain chemicals that would naturally dissipate are then trapped in the brain.

Dopamine is the specific neurotransmitter in which drugs try to replicate or over produce. This is the neurotransmitter naturally found in the areas of the brain that control movement, emotion, cognition, motivation, and feelings of pleasure. Over stimulating the brain or flooding the network with dopamine is what gives the drug user the “high” sensation.

Dopamine and how it changes the human brain
Dopamine and how it changes the human brain
An addiction to drugs is something that changes the brain.
An addiction to drugs is something that changes the brain.

Why does this become an addiction?

Dopamine is naturally stimulated in the brain during times of happiness or pleasure. It is released when we feel happy in our lives, feel accomplished, feel appreciated, are proud or excited for something, are in love, having sex, etc. There are so many times that dopamine is released in the brain. It is essentially the “happy brain chemical” as it is present during the happiest times. Someone suffering from depression is often lacking the amount of dopamine that should be normally traveling in the brain. Thus, we refer to depression as a chemical imbalance.

Our brains are wired to remember these things. If it causes happiness, the brain writes it down as something important and it must be repeated. Our brain encourages the “good” activities and teaches us to do them again and again. To a non-addict, these activities are not harmful. To an addict, it is the drug that the brain has been trained to seek out and repeat.

A drug causes more dopamine to be present in the brain than would ever normally be. In some cases, there can be up to 10 times more dopamine present. It over saturates and over stimulates the brain, causing a sensation of extreme pleasure. This results in the brain attempting to balance itself out, causing there to be even less dopamine present than what should be during normal times of pleasure and happiness.

A drug addiction can come in many forms
A drug addiction can come in many forms

What are the long term effects of drug use?

After continued drug abuse, the brain is incapable of communicating pleasure in any circumstance other than when the drug is present. A person will stop feeling good about anything in their lives and it is not a choice. The brain is preventing them from enjoying anything in life. The addict will desperately seek that pleasure and happiness which only comes in the form of their chosen drug. The brain adjusting to the dopamine is what is often referred to as tolerance. The user will have to use a larger amount of the drug in order to achieve the same “high” that they once did.

Altering the way the natural cell and chemicals in the brain can have extremely harmful long term effects. The increased amount of artificial and natural dopamine causes the other neurotransmitters to be pushed out of production. The brain can only hold so many of these. Once you fill the brain to the brim with dopamine, there is not room for the brain to send the other necessary messages.

The nerve cells that normally send out these other signals will learn to not send them when they are needed. This can cause malfunction in the way we talk, move, think, feel and learn. As the nerve cells learn to prevent these signals from being sent out, the brain is less likely to regain this function fully ever again. Therefore, a drug addict can potentially cause issues that will remain long after the addiction has been controlled.

What can be done?

The best possible outcome for a drug addict is for the addiction to be controlled. The early it is treated, the more likely it will be for the person to overcome the side effects. The longer they use drugs, the more likely they are to do permanent damage to themselves.

If you or a loved one is suffering from drug addiction, call 1-800-662-HELP to find a treatment center near you. Or visit

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    • cheaptrick profile image


      5 years ago from the bridge of sighs

      Nicely written. Addiction is an interesting subject and you handle it well.Would like to read a hub about nondrug addictions like work, love, sex etc. Chemically, the same reaction occurs in the brain with 'falling in love' as taking heroin;The brain doesn't morally discriminate. If you write a hub I'm sure you'd get lots of interest. I know I'd read it.


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