What Does Long-Term Drug Use Do to the Brain?

Substance abuse impacts the brain in the short-term to create a euphoric high or exert other effects such as sedation, pain relief, etc.¹ However, long-term drug use can also result in more fundamental changes in the brain that can last for years or even a lifetime.^2,3

How Do Drugs and Alcohol Affect the Brain?

According to the National Institute on Drug Abuse (NIDA), drugs produce their effects by changing the ways the brain’s neurons process information via neurotransmitters.⁴

These changes in brain functioning can propel the compulsive use indicative of a substance use disorder, but they can also impact the brain in ways that create other lasting issues such as problems with learning, memory, and judgment.^4,5

What Parts of the Brain Are Affected by Drug Use?

NIDA discusses 3 main regions of the brain that are impacted by substance use and abuse: ⁴

• The basal ganglia (which makes up a key part of the reward circuit and is involved in the formation of habits and routines).
• The extended amygdala (which plays a role in dependence and the feelings of stress and anxiety during withdrawal).
• The prefrontal cortex (essential for higher cognitive functions like decision-making and impulse control).

By interfering with these areas, drugs can:⁴

• Produce a powerful addictive high and, over time, some drugs will diminish the brain’s ability to feel substantial pleasure from natural rewards like food, sleep, sex, or exercise.
• Cause adaptations in the brain such that a person goes into withdrawal when drug use slows or stops.
• Impair a person’s ability to think, solve problems, create a plan, and control their impulses. Because the prefrontal cortex is the last part of the brain to fully develop, adolescents and teens who abuse drugs are most at risk of the lasting impact of drugs on this region of the brain.

What is Dopamine and How Do Drugs Affect It?

All addictive drugs trigger the release of dopamine.⁶ In past years, it was believed that dopamine was directly responsible for the intense euphoric high that a drug produced, but experts now believe that dopamine plays a more complicated role.⁴

Dopamine surges signal to the brain that an activity should be remembered and makes it easier for it to be repeated. For example, if a person enjoys a nice meal, a little surge of dopamine occurs to help the brain remember to eat that meal again. This role dopamine plays in repetition of behavior helps us create habits.⁴  

Drugs produce much larger bursts of dopamine than a natural reward like a meal would, however, so they create a very strong connection between taking the drug, the pleasure that comes afterward, and all of the cues around the person that are linked to their drug consumption (for example, the location where the drug is used). As these connections are created and strengthened, the brain begins learning to prioritize getting and taking drugs over seeking out natural, healthy rewards.⁴

Because dopamine helps to create such powerful connections in the brain, the external cues associated with drug use can trigger overwhelming drug cravings years after a person has gotten clean.⁴ This is one of the reasons that recovery is a lifetime pursuit and that relapse is so common.

How Does Addiction Change Your Brain?

Addiction is characterized by a compulsion to keep using a drug, or drugs, in light of the adverse consequences that arise as a result of doing so. Addiction, once thought to be a problem of morality and bad decision-making, has now become recognized widely as a chronic and relapsing disorder that involves changes to the brain that can be long-lasting.^7,8

The brain changes that occur with repeated substance use make getting sober much more difficult than simply saying “no” to drugs. When a person first uses a drug, it is a choice; however, the person’s ability to control their use becomes diminished as brain functioning changes and addiction takes hold. NIDA compares addiction to heart disease, stating that both diseases cause an essential organ of the body to stop functioning optimally and that, without treatment, both diseases can lead to death.⁷

A person struggling with addiction often requires treatment—sometimes multiple attempts at treatment—to find long-lasting recovery.⁹ Treatment can help people learn to manage their addiction and develop tools and skills to cope with cravings, triggers, and other challenges that arise with sobriety.

Which Drugs Cause Long-Term Damage to Your Brain?

Different drugs are associated with varying long-term effects on the brain. While the changes that drive addiction are relatively universal, specific classes of drugs are associated with other unique effects on the brain.

The brain changes discussed below do not represent an exhaustive list of all changes that may occur as a result of using these drugs.

Long-Term Effects of Opiates on the Brain

Some opioid-dependent individuals have exhibited concerning brain changes such as:¹⁰

• Alterations in the brain’s white matter tracts. Abnormalities of the white matter tracts in the brain may be linked to antisocial behavior, including violence and aggression.¹¹
• Changes in functional interconnectivity between certain brain regions. Disrupted interconnectivity may cause issues with cognitive processing. It may also be an indicator of structural changes in the brain.
• Loss of volume in the amygdala, as well as impaired information processing by the amygdala.

Opioid Overdose and Brain Injury

Individuals who abuse opioids are also particularly at risk of overdose, especially with the proliferation of super-potent synthetic opioids such as fentanyl on the street. An overdose from opioids involves severe respiratory depression that, if not treated quickly, may result in hypoxia-related injuries. Hypoxia refers to insufficient oxygen in the tissues.¹²

A lack of sufficient oxygen for long enough may lead to brain injury. Hypoxia-related brain injury can result in:¹³

• Confusion/disorientation.
• Memory problems, such as short-term memory loss.
• Behavior changes.
• Impaired cognitive functioning.
• Decreased motor skills and reaction time.
• Problems walking.
• Paralysis.
• Incontinence.

Long-Term Effects of Benzodiazepines on the Brain

There is some evidence to indicate the benzos are linked to cognitive decline. While cognitive function has been shown to improve once benzodiazepines are withdrawn, it does not appear to return to pre-benzodiazepine levels even after sustained periods of abstinence.¹⁴

Benzodiazepines have also been shown to cause memory problems and can produce anteretrograde amnesia, a condition in which a person is unable to create new memories.^15,16

Furthermore, benzodiazepines are associated with an increased risk of Alzheimer’s disease.¹⁷ One study of nearly 9,000 elderly individuals in Quebec found that the risk of developing Alzheimer’s was increased by up to 51% in those who had used benzodiazepines at some point in the past and that higher risk was linked to long-acting benzos such as Valium.¹⁷

Long-Term Effects of Alcohol on the Brain

Alcohol has numerous short-term effects on the brain, such as slowed reaction time and memory lapses, but it may also lead to significant long-term harm. For example, chronic alcohol use may result in brain shrinkage, and women may be particularly vulnerable to this effect.¹⁸

Alcoholism can also affect the brain indirectly. Alcoholism often results in poor nutrition and can lead to a deficiency in vitamin B1 (thiamine). In fact, the National Institute on Alcohol Abuse and Alcoholism states that up to 80% of those with alcohol use disorders have a thiamine deficiency. Unfortunately, this can have dire consequences for the brain.¹⁸

Thiamine deficiency can lead to a brain disorder called Wernicke-Korsakoff syndrome, a disease that combines Wernicke’s encephalopathy and Korsakoff’s psychosis.¹⁸ Wernicke-Korsakoff syndrome symptoms include:¹⁸

• Confusion.
• Paralysis of nerves in the eyes.
• Decreased muscle coordination.
• Severe memory and learning problems.

Alcohol is also known to be very harmful to the developing brain. Alcohol use during pregnancy may result in numerous problems ranging from learning difficulties to behavioral issues. In the most severe cases, a child may develop fetal alcohol syndrome. This condition may cause distinct facial features, smaller brain size, and fewer brain cells that function properly.¹⁸

Long-Term Effects of Stimulants on the Brain

Prescription stimulants like Adderall, which are often abused as “study drugs,” have a reputation for boosting mental performance, but in fact research shows that stimulant abuse can decrease the brain’s plasticity, causing problems with executive function and decreasing cognitive and behavioral flexibility. This can be particularly concerning for someone who has become addicted to stimulants, as behavioral flexibility (the ability to adapt behavior as necessary in different situations) is critical to recovering from substance use disorders. Young people whose brains are still developing may be more susceptible to these changes.¹⁹

The abuse of illicit psychostimulant drugs such as methamphetamine and cocaine are linked to depressive symptoms.²⁰ Symptoms such as a low mood or irritability will often resolve during periods where stimulants are not used. However, other symptoms like anhedonia (the inability to feel pleasure) and lack of motivation may persist even after sustained periods of sobriety.²⁰

Long-term methamphetamine users may experience psychotic symptoms (paranoia, delusions, etc.) that may persist long after they’ve quit using the drug. Stressful situations may bring on spontaneous psychosis in former meth users.²¹

Chronic methamphetamine use may also cause significant functional and structural brain changes in areas related to emotion and memory. Additionally, similar problems with flexibility as those that occur in relation to prescription stimulant use may occur as a result of meth use. These individuals may find it incredibly difficult to stop useless or counterproductive behaviors, again making long-term recovery from addiction that much more difficult.²¹

Long Term Effects of Marijuana on the Brain

Marijuana is widely believed to be relatively harmless, but this may not be the case, especially as recreational marijuana strains are becoming more potent than ever.²² One study found that smoking marijuana with high levels of tetrahydrocannabinol (THC) can cause damage to a part of the brain called the corpus callosum, which collects and transfers information from both hemispheres of the brain to process motor, sensory, and cognitive signals.^23,24

Altered brain development may also occur in adolescents who use marijuana. Frequent use during youth has been associated with significant declines in an individual’s IQ.²⁵

Marijuana use also increases the risk of schizophrenia and other chronic psychotic disorders in those who are predisposed to such disorders.²⁵

Long-Term Effects of Hallucinogens on the Brain

Classic hallucinogens such as LSD and mushrooms have two major long-term effects on the brain:²⁶

• Persistent psychosis. This condition may cause visual and mood disturbances, paranoia, and problems organizing one’s thoughts.
• Hallucinogen persisting perception disorder (HPPD). This involves the repeated occurrence of flashbacks and visual disturbances like seeing halos.

What are the Long-Term Psychological Effects of Drug Abuse?

Drug addiction very commonly occurs alongside mental health disorders, such as anxiety disorders, depression, and bipolar disorder. An estimated 25% of people with a serious mental illness also suffer from a substance use disorder.²⁷ Drug use in a person’s youth may increase their risk for the development of both substance use disorders and mental health disorders later in life.²⁷

Substance use can worsen the course of mental disorders and vice versa. The National Alliance on Mental Illness explains that someone with a mental health disorder may look to drugs or alcohol to cope with their symptoms only to find it actually worsens their symptoms.²⁸

Integrated treatment that addresses both the substance use disorder and the mental health disorder may be needed for a person to find and sustain recovery. Laguna Treatment Center offers co-occurring disorder treatment in a beautiful California setting. Getting treatment can prevent or, in some cases, reverse the harmful effects of drugs on the brain and help restore you to optimal health. Call us at today to learn more about our hospital-based detox and inpatient rehab programs.

If you or a loved one is struggling with substance abuse and you live in California, you can search for inpatient rehab programs in Orange County, to start your road to recovery.