How Does Substance Use Disorder (SUD) Affect the Brain?

Substance use disorders (SUDs) are complex disorders of the brain, with addiction being the most severe form of SUD. These disorders range in severity and intensity, affecting every individual differently. However, what all SUDs have in common is that they affect an individual’s brain and behavior in long-lasting ways. 

While it is often common knowledge that SUD and addiction are problematic, many individuals still do not recognize that these conditions affect the brain on a biological level. Those with loved ones struggling with SUD may feel compelled to view their loved one’s recurrent alcohol or drug use as a choice. However, becoming educated about how SUD affects the brain can help reduce feelings of victimization and increase understanding toward those who are struggling. 

How Does the Brain Work?

Before understanding how alcohol and other drugs impair brain functioning, it is important to become familiar with how the brain works naturally. The National Institute of Neurological Disorders and Stroke (NINDS) explains that the brain is the most complex organ within the human body. They state, “This three-pound organ is the seat of intelligence, interpreter of the senses, initiator of body movement, and controller of behavior. . . the brain is the source of all the qualities that define our humanity.”

The National Institute on Drug Abuse (NIDA) compares the functions of the brain to the functions of a computer network. However, rather than electrical circuits running a computer, the brain is run by billions of tiny cells known as neurons. Neurons are organized into different networks, formed to control the flow of information and to carry out specific responsibilities. 

Think of a neuron as a switch. Neurons work together by releasing messages, known as neurotransmitters, to other neurons. When a neurotransmitter is received by a neuron, it attaches, like a key in a lock, and causes changes to receiving cell. Other neurons are responsible for recycling neurotransmitter messages after they have been sent. These molecules, known as transporters, can shut off or limit signals sent between neurons. 

How Do Drugs Affect the Brain?

The NIDA explains, “Drugs interfere with the way neurons send, receive, and process signals via neurotransmitters.” Every class of drug does this differently. 

Stimulant Drugs

For example, stimulants are drugs that increase the activity of neurotransmitters in the central nervous system (CNS), which often cause increased alertness, attention, concentration, and energy. Common stimulant drugs include amphetamines (prescriptions typically used to treat attention-deficit/hyperactivity disorder) and cocaine.

In the brain, stimulants cause neurons to release abnormal surges of neurotransmitters. Some stimulants also block the normal recycling of neurotransmitter signals by interfering with transporter molecules. This disrupts the normal communication between neurons in the brain by amplifying it. 

Depressant Drugs

On the other hand, depressants are drugs that slow CNS activity. Depressant drugs can cause muscle relaxation, induce sleep, and prevent seizures. Common depressant drugs include alcohol, opioids, sleeping pills, barbiturates, and benzodiazepines. 

In the brain, depressant drugs increase the activity of the neurotransmitter GABA, which is known to slow brain activity. In general, they slow messages between neurons in the brain and body, which can affect both automatic and manual bodily functions. This disrupts normal communication between neurons by slowing it down.

The Effects of Other Drugs

Stimulants and depressants are just two types of drug classes. The NIDA also emphasizes the effects of other drugs, including marijuana, on the brain. They explain that the chemical structure of marijuana actually mimics the structure of a natural neurotransmitter in the body. 

As a result, marijuana can activate neurons in the brain. However, it is important to understand that although the chemical structure of marijuana mimics natural neurotransmitters, it activates neurons abnormally. This causes abnormal messages to be sent throughout the brain. 

The Biological Effects of SUD

While any kind of drug use can cause lasting brain changes, the effects of chronic use of alcohol and other drugs on the brain are yet to be discussed. Often, most people’s initial choice to use or experiment with substances is voluntary. With chronic use, however, the compulsive need to engage with alcohol and other drugs is no longer an option but a necessity for well-being. 

The Brain’s Reward Circuit

All areas of the brain are uniquely impacted by chronic drug use. One of the most significant areas affected is known as the brain’s reward circuit. This circuit is responsible for motivating individuals to repeat behaviors that bring feelings of pleasure. 

A circuit that has not been exposed to alcohol and drug use will encourage natural and healthy behaviors, such as eating, socializing, and having sex. The main neurotransmitter involved in this circuit is dopamine, which is responsible for the reinforcement of pleasurable behaviors. 

When a person is exposed to the effects of alcohol and other drugs, their reward circuit becomes compromised. This is because chemical substances produce significant surges of dopamine – unlike anything produced from natural rewards. As an individual reengages with alcohol or other drugs repeatedly, the reward circuit adapts to it, and an individual will need more of a substance to achieve its desired effects. This phenomenon is known as drug tolerance. 

Additionally, the increased use of alcohol and other drugs will also produce withdrawal symptoms. Over time, the main goal of substance use shifts from attempting to achieve a desired high to merely attempting to numb severe withdrawal symptoms. This is how voluntary substance use can quickly shift into addictive behavior. 

Seeking Recovery From SUD

When it comes to addiction and SUD, there is much more than meets the eye. Recovery is more than just stopping substance abuse; it involves working to reverse the brain changes that result from chronic substance use. The task is not just getting sober but learning how to challenge brain dysfunction and healthily cope with stress while preventing relapse. Fortunately, professional treatment and support can help loved ones seeking recovery to achieve lasting healing from these concerns. 

Substance use disorder (SUD) is a chronic and complex brain disorder affecting an individual’s thoughts, feelings, and behavior. Professional treatment can help reverse lasting brain changes caused by repeated substance use. We at 12 South Recovery utilize a client-centered philosophy of treatment for our clients, which means we tailor treatment to fit your individualized needs. We offer partial hospitalization (PHP), intensive outpatient (IOP), and general outpatient (OP) programming to ensure that we have a program for everyone at our facility. Within our programs, we offer a wide range of therapeutic techniques to help meet clients exactly where they are in their healing journey. To learn more about our program, call 866-839-6876.

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