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Can Drugs Cause Mental Illness? The Cause & Effect of Drugs on Mental Health

do drugs cause mental illness

Research has long connected substance abuse to mental illness. Experts report that close to 40 percent of individuals with substance addiction also struggle with mental health disorders like depression and anxiety. Among adolescents, in particular, it’s estimated that 60 percent of those in addiction treatment programs also meet the diagnostic criteria for mental illness. But why is this the case? Do drugs cause mental illness, or are other factors at play?

The truth is, there is no single explanation for the relationship between drugs and mental illness. While substance abuse often does trigger the onset of mental health issues, the same can be said vice versa: Mental health disorders also can lead to drug use, too. Research shows that those with severe mental illness are 3.5 times more likely to use marijuana regularly, and almost 5 times more likely to use other illicit drugs, compared to the general population.

Still, it’s important to underline the fact that drug abuse can lead to the emergence of mental health symptoms, and the reasons for this are multifaceted. Let’s explore them more below.

How Drugs Can Cause Mental Illness Symptoms

  1. Drugs change a person’s brain composition.

Drugs—including marijuana, cocaine, and prescription painkillers—are chemicals that have the fundamental ability to change our brain’s make-up with frequent or long-term use. Specifically, drugs interfere with the way neurons send, receive, and process signals in the brain. They have the ability to activate our brain’s reward system in unnatural ways, and re-wire parts of the brain that are responsible for memory, learning, judgement, self-control, and decision-making. 

The parts of the brain that are affected by substance abuse are the same areas of the brain affected by other mental health disorders, such as schizophrenia, anxiety, mood disorders, and impulse-control disorders. This makes a person more vulnerable to disruptive mental health symptoms. As stated by the National Institute on Drug Abuse, “Drug use that precedes the first symptoms of a mental illness may produce changes in brain structure and function that kindle an underlying predisposition to develop that mental illness.”

Drug abuse is thought to be most problematic during adolescence, when the brain is undergoing dynamic changes. When drugs are introduced during this critical period of development, their use becomes an engrained behavior and increases one’s likelihood of developing an addiction or other mental health disorder down the road. For example, the NIDA reports that “frequent marijuana use during adolescence can increase the risk of psychosis in adulthood, specifically in individuals who carry a particular gene variant.” For this reason, early drug abuse—and any sequential signs of mental illness—should be addressed immediately.

  1. Withdrawal from drugs causes an array of mental health symptoms.

While withdrawal from drugs and alcohol may not cause mental illness directly, it can create space for a range of difficult mental health symptoms. Withdrawal is the body’s physiological response to suddenly quitting drugs after an extended period of time, and happens when the body has become reliant on those drugs to function. Symptoms of drug withdrawal are often physical, such as tremors, high blood pressure, nausea, and fatigue. However, many do not realize that withdrawal often triggers mental health problems such as:

  • Depression
  • Anxiety
  • Paranoia
  • Hallucinations
  • Sudden and severe mood changes
  • Anger and irritability
  • Loss of motivation

Withdrawal from drugs and alcohol typically is not a long-term occurrence, and can be alleviated as a person detoxes their body from the substances used. However, there is such thing as post-acute withdrawal syndrome, where these symptoms can last for months or even years after drug use has stopped. The long-term nature of this syndrome – and the long-term struggle with difficult physical and mental health issues – can take a toll on a person’s emotional and mental well-being. 

  1. Some drugs are linked to psychosis.

There is a growing body of research that is connecting substance abuse to psychosis, formally known as substance-induced psychosis. Substance-induced psychosis means that there a person has developed delusions or hallucinations, either during intoxication, withdrawal, or within a month of using drugs. While these symptoms can be temporary, it is estimated that close to one-third of substance-induced psychoses may convert into either schizophrenia or bipolar disorder.

Many drugs have psychotomimetic properties, causing psychotic symptoms while intoxicated. However, studies show that these drugs also have the potential to cause a syndrome that directly resembles a psychotic disorder, such as schizophrenia. 

Problematic drugs that have been studied range from illicit substances like cocaine and hallucinogens, to new substances like synthetic opioids and synthetic marijuana. One study, published in 2017, found that even marijuana use during the adolescent years represents significant risk: “In teenagers – and, in particular, in the 12-15 age range – teenagers who are smoking daily are at about threefold higher risk of developing schizophrenia down the road.”

So, Do Drugs Cause Mental Illness?

While drugs can trigger the onset of mental health symptoms, it is difficult to offer a definitive “yes” to this question. This is because there are a variety of other risk factors that make one vulnerable to mental illness. Drug use can stir up and surface mental health problems, but it is possible that the individuals affected have already been predisposed to mental illness in some way: through genetics, chronic stress, abuse and trauma, or other environmental factors. Learn about the risk factors for mental illness here.

Regardless of these nuances, though, there is no denying the relationship between mental illness and substance abuse. Co-occurring disorders are common, with over eight million adults in the U.S. struggling with both a mental illness and substance use disorder. At the end of the day, the causes of mental illness, and the causes of substance addiction, are manifold. And no matter what they are, the most important thing is what happens next. 

Mental illness and substance use disorders are chronic, complex conditions that often require professional support. If you or your loved one is struggling, you do not need to do so in silence. Getting help now – especially for young people – can set you up for a lasting recovery and productive, fulfilling life long-term. 

If you are interested in learning how Turnbridge can help, please do not hesitate to reach out. Turnbridge offers mental health and substance use disorder treatment programs for adolescents and young adults struggling. Call us at 877-581-1793 to speak with a specialist.