How drugs change your feelings.

By David Joel Miller, MS, Licensed Therapist & Licensed Counselor.

Brain circuits.

Photo courtesy of

Drugs of abuse alter the chemical balance in your brain.

PNG of brain.

Photo courtesy of

The human brain is a very complex organ. Everything you think, feel, experience, or do is the result of brain activity. Drugs, especially drugs of abuse, can alter the chemical balance in your brain either temporary or sometimes permanently.

The brain is made up of millions of tiny nerve cells called neurons. These nerve cells connect to each other through billions of tiny nerve endings. In the early days of physiological psychology, this all seemed so simple.

Electricity moves information within a nerve cell.

Early on, we discovered that a nerve cell can develop an electrical charge and when this charge moved down the nerve cell, it transmitted information. Electrically stimulating a rat’s brain might cause him to move the leg.

Electrical stimulation doesn’t explain everything. Between one nerve cell and the next, there are infinitesimal, small gaps. Scientists refer to those gaps as synaptic gaps, or sometimes they speak of the connections between cells as synapses. It turns out that electricity doesn’t flow very well from one brain cell to another through the brain fluid.

Information moves from one nerve cell to another chemically.

The human nervous system manufacturers a large number of chemicals, some of which are called neurotransmitters. When I first studied the subject in the 1960s, we study two neurotransmitters. Today hundreds of neurotransmitters have been identified and studied. The more research I read, the more newly identified neurotransmitters I encounter.

Drugs of abuse alter the way information moves between cells chemically.

For a drug of abuse to affect the way you think, feel, or behave, it needs to do two things. First, it needs to get into your brain. The brain contains a large amount of fluid. Protecting that fluid from contamination is the blood-brain barrier. This membrane is designed to keep undesirable material out of your brain. All drugs of abuse must have molecules that can get through this blood-brain barrier.

Each neurotransmitter has a shape which fits a receptor in the next cell.

You hear a gun go off and your nervous system produces a stimulant chemical that gets your heart pounding and prepares you for action. That stimulant chemical is sometimes called adrenaline. A similar chemical is found in the nervous system. We, here in the US, call that chemical norepinephrine, in some other countries it is called noradrenaline. This chemical fits into receptors on other cells and causes them to act.

One of the explanations for how drugs of abuse affect your nervous system is called the “lock and key theory.” Each naturally occurring neurotransmitter has a shape, and other cells have a receptor designed to accept that shape. So, when your nervous system sends out norepinephrine, it fits into receptors throughout your nervous system to prepare you to take immediate action.

Drugs of abuse mimic the shapes of naturally occurring neurotransmitter.

Stimulant drugs, such as cocaine or methamphetamine, are shaped in a way that is similar to norepinephrine. Because they mimic a natural neurotransmitter’s shape, they can make all the circuits in your nervous system fire.

Drugs of abuse not only activate a few cells, but they can activate many cells in far more emphatic ways than your naturally occurring neurotransmitters do. Because of this, drugs of abuse can feel very pleasurable, but only for brief periods of time. Each time you use a drug, it changes the chemical balance in your brain. Over time it changes the balance so much, you are unable to feel the things you used to feel unless the drug is present in your system.

Of course, the process in the brain is far more complicated than this simple description. Many other things are taking place every time you think a thought or the chemistry in your brain changes. Understanding how drugs of abuse mess with the way your nervous system works helps to explain a large part of how those drugs can lead to abuse, dependence, addiction, and a whole range of disorders we call substance use disorders.

For more on this topic see – Drug Use, Abuse, and Addiction and Recovery

Staying connected with David Joel Miller

David Joel Miller MS is a Licensed Marriage and Family Therapist (LMFT) and a Licensed Professional Clinical Counselor (LPCC.)  Mr. Miller provides supervision for beginning counselors and therapists and teaches at the local college in the Substance Abuse Counseling program.

Two David Joel Miller Books are available now!

Bumps on the Road of Life. Whether you struggle with anxiety, depression, low motivation, or addiction, you can recover. Bumps on the Road of Life is the story of how people get off track and how to get your life out of the ditch.

Casino Robbery is a novel about a man with PTSD who must cope with his symptoms to solve a mystery and create a new life.

For these and my upcoming books; please visit my Amazon Author Page – David Joel Miller

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For more about David Joel Miller and my work in the areas of mental health, substance abuse, and Co-occurring disorders see my Facebook author’s page, davidjoelmillerwriter. If you are in the Fresno California area, information about my private practice is at


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