How Addiction Affects the Brain

Estimated reading time: 31 minute(s)

Millions of Americans currently suffer from various addictions, which constantly increase with each passing day. While most of these people are under the impression that using drugs or alcohol makes their lives easier and fills them with happiness, the reality is addiction can severely affect mental health and brain functioning. The highly potent drugs most people abuse can interact with the brain, altering mood, behaviors, and perception differently. If you or a loved one has been abusing a substance for a long time, it is high time to devote some time to understanding how addiction affects the brain and its potential side effects on mental health.

How Addiction Affects the Brain: Latest Insights into a Prevalent Problem

Most people fighting addictions are the ones who accidentally fell into the trap and got caught in its snare. As per the latest surveys, almost 23 million people across the United States, or one out of every ten, are currently fighting an addiction to drugs or alcohol. Over two-thirds of these people abuse alcohol and other drugs, the top three of which include opioid pain relievers, cocaine, and marijuana.

The earliest research on addiction and its development mechanism began during the 1930s when the scientific community united to discover the actual causes. Before this research began, society considered people with addictions a consequence of no willpower or moral flaws. Hence, they believed that punishing miscreants or forcing them to break the habit was the only way to eliminate these addictions.

Thankfully, modern research and advancements have changed these beliefs. Today, the world recognizes addiction as a long-term illness that can alter the brain’s function and structure. Just like diabetes affects the pancreas and a cardiovascular illness damages the heart, addiction appears to hijack the brain. It forces the chief organ of the body to undergo a series of changes that begins with an enhanced recognition of pleasure and ends with a heightened drive toward compulsive behavior.  

Addiction and the Brain: The Pleasure Principle

When it comes to pleasure, the brain does not distinguish. It registers all of them similarly regardless of their source, such as a sexual encounter, a monetary award, or a psychoactive drug. Pleasure holds a distinct signature in the brain, i.e., the release of dopamine neurotransmitters in an area called the nucleus accumbens. This dopamine surge in the nuclear accumbens has been associated with intense pleasureful feelings; hence, the region has been termed the pleasure center.

All types of drugs, such as heroin, opioids, or nicotine, work by causing a powerful dopamine surge in the nucleus accumbens. The likelihood of a particular substance triggering addiction in a person is associated with how rapidly it releases dopamine and the reliability and intensity of this release. This phenomenon explains why an individual may be at variable risks of addiction to the same drug consumed through different methods. For instance, injecting a drug intravenously or smoking it can lead to a faster and much more potent dopamine signal than oral ingestion; hence, they may lead to a higher risk of addiction.

To explain addiction in short words, an addictive drug provides the user with a shortcut to trigger the brain’s reward system by releasing tons of dopamine in the nucleus accumbens. The hippocampus notes this rapid sensation of pleasure and happiness, and the amygdala forms a conditioned response to specific stimuli that force users to recreate the pleasureful memories.

Drugs and the Brain: Effect of Addiction on the Learning Process

Scientists once believed that the pleasure experience alone is enough to force people into an addictive habit. However, recent research has suggested that the actual situation is much more complicated than it once was. Dopamine, the primary neurotransmitter for addiction, not only triggers pleasure but also plays a role in memory and learning. Both memory and learning are two primary elements that make a person move from liking something to developing an addiction to it.

As per the current addiction theories, dopamine interacts with glutamate, another neurotransmitter, to take control of the brain’s reward system related to learning. This system plays a crucial role in maintaining life and survival by influencing important pleasure-related activities, such as sex and eating. The reward circuitry in the brain includes areas associated with memory, motivation, and pleasure, and addictive substances can stimulate and overload these areas.

What Does Addiction Do to the Brain?

Addiction can affect the brain in different ways, such as the following:

Changes in the Homeostatic Environment

Psychoactive substances can affect the brain by altering an essential biological process in the brain called homeostasis. The human body has a biological system that maintains different systems in an average balance, called homeostasis. The brain works as a chief supervisor, ensuring this system stays balanced. Each person has a different level of homeostatic balance, and drug abuse can alter it in several ways.

When constant drug use overstimulates the brain, it interferes with homeostasis. Being a remarkable organ, the brain adapts to these circumstances to make adjustments, usually by setting a new balanced set-point. This newly created balance is known as allostasis. While allostasis can cause significant changes in neural functioning, it may also lead to certain addiction-related behaviors, such as:

  • The vital need to obtain drugs.
  • The urge to continue harmful activities.
  • The all-consuming nature of addiction forces a person away from everyday activities.

Changes in Chemistry

The brain has two types of neurotransmitters: excitatory and inhibitory. Excitatory neurotransmitters can activate neurons and make them fire or conduct a message across. The other type of neurotransmitters, i.e., inhibitory neurotransmitters, prevent the neurons from conducting messages. Glutamate is the most common example of an excitatory neurotransmitter, whereas gamma-aminobutyric acid (GABA) is an example of an inhibitory neurotransmitter. Both types of neurotransmitters in the brain play a crucial role in the development of addiction. Other neurotransmitters commonly associated with addiction include the stress hormones dopamine and acetylcholine.

Some of these neurotransmitters are sensitive to certain drugs. Some examples include the following:

  • Methamphetamines and cocaine affect dopamine
  • Ecstacy affects serotonin and dopamine
  • Nicotine works by inducing changes in the acetylcholine system
  • Alcohol works by altering glutamate, GABA, and dopamine
  • Marijuana activates the cannabinoid system and dopamine
  • Opiates, such as Vicodin, oxycontin, codeine, and heroin, cause changes in GABA, opiate, and dopamine

Decreased Synaptic Activity

Drug abuse can affect the brain much more intensely than natural rewards, such as a certain social interaction or a delicious meal. To manage this overstimulation, the organ tries to adapt and compensate by reducing the number of dopamine receptors present at the synapses. Additionally, the brain signals neurons to increase the total number of dopamine transporters to clear up the flooding levels of this neurotransmitter from the system. Together, these adaptive responses make the brain much less responsive to the drug. While this helps the brain decreases the response towards drug use and allows users to come down, most people need higher amounts of the sought-after substance to get high.

Rewired Brain Connections

As the brain constantly adapts to the presence of a particular substance, some of its areas not related to the reward pathway also sustain collateral damage. For instance, constant drug use affects the brain areas controlling learning, decision-making, judgment, and memory. These changes may also make certain behaviors, such as drug use, “hard-wired,” meaning they become driven by habit.

How Addiction Affects the Brain: Developing Tolerance and Compulsion

As the brain undergoes various changes mentioned above, it slowly starts developing tolerance toward the sought-after substance, making it less pleasurable. In reality, rewards come with effort and time, but when a person starts using an addictive drug, they get a shortcut to get to these rewards. The daily use of drugs floods the brain with various neurotransmitters, such as dopamine. Some addictive drugs can release up to ten times more dopamine than a natural reward ever can. Moreover, this excessive dopamine release is much quicker and more reliable than what a natural reward may secrete. As a response to these high dopamine levels, the brain reduces its natural dopamine production to adapt to the ongoing circumstances. This adaptation is similar to when a person turns down the volume on a loudspeaker when the noise becomes too loud to bear.

As a consequence of these brain adaptations, dopamine’s impact on the brain’s reward center becomes lesser. People on the way to addiction frequently find that their desired substance cannot give them as much pleasure as they used to. Hence, they must increase their daily substance dose to experience the same dopamine “high.” This phenomenon is scientifically termed tolerance.

Once tolerance develops, compulsion takes over. The addict remembers the memory of the pleasures they experienced by using a substance and tries to recreate it as much as possible. The learning process, mentioned earlier in the article, also plays a role in solidifying this compulsion. The memories of previous drug use and the cues associated with them are available in specific brain areas called the amygdala and hippocampus, and the brain uses them to develop conditioned responses, such as intense cravings, whenever they come into contact with specific environmental cues.

Remember that substance cravings fuel addiction and increase the risk of relapse following sobriety. For instance, a person who formerly used to abuse heroin may relapse upon seeing a hypodermic needle. Alternatively, a bottle of whisky may lead to intense cravings in a former alcoholic, forcing them to relapse. Hence, it is imperative to seek complete addiction through a certified, professionally-monitored program where an addict can learn how to overcome their triggers and manage them in the long run for sustained recovery.


How does addiction resemble a chronic physical illness?

Experts consider addiction similar to any other chronic illness because both share the following characteristics:

  • Both are preventable
  • Both change the core biology
  • Both are treatable
  • If left untreated, both may last for life

What role does dopamine play in addiction?

All drugs with the potential to cause addiction primarily affect the reward pathway in the brain. This pathway induces happiness and pleasure; dopamine is the chief neurotransmitter controlling these emotional changes. When a person uses an addictive drug, the drug dramatically changes the brain’s synapses and turns on the reward circuitry in the brain. Once this circuit turns on, dopamine levels increase, creating intense happiness and pleasure.  

How can I know if I have an addiction?

Determining if you suffer from addiction is not as straightforward as it may seem. Admitting it may also not be so easy, mainly due to the stigma attached to it. However, rightfully identifying it in time and acknowledging the problem can be the first step toward recovery. To know if you suffer from addiction, ask yourself the following questions:

  • Are you using a particular substance more often than you used to?
  • Do you develop withdrawal symptoms when you fail to use the substance?
  • Do you lie to others about your substance use?

If you answer yes to any of the questions above, you might suffer from an underlying addiction. You must consult a healthcare provider for further assessment and support.

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