Schizophrenia and Substance Abuse

Schizophrenia is a complex and severe mental health disorder that affects an afflicted individual’s ability to think, feel and act. Often characterized by hallucinations, paranoia and loss of a sense of reality, schizophrenia is frequently accompanied by substance use disorders.

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Schizophrenia is a debilitating mental disorder that affects the way an individual thinks, acts and feels. Those with schizophrenia may hear voices in their head or see things that do not exist. They may display signs of paranoia, psychosis and irrational or delusional thinking. Schizophrenia is also linked to high rates of addiction.

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Co-occurring disorders, when a mental health disorder and another health disorder such as a substance addiction occur concurrently, are common among those with schizophrenia. Approximately 50 percent of individuals with schizophrenia have a history of substance abuse or addiction, according to a variety of studies cited by the U.S. National Library of Medicine.

Co-occurring substance use disorders can hinder the effectiveness of schizophrenia treatment and vice versa. Those with schizophrenia are also less likely to engage in treatment for their mental disorder when abusing drugs or alcohol.

Substance abuse also increases the risks of suicide, trauma and homelessness among those with schizophrenia, in addition to other health risks. The most commonly abused substances among individuals with schizophrenia are nicotine, alcohol, marijuana, cocaine and psychedelic drugs.

Experts believe individuals with schizophrenia abuse substances to self-medicate and alleviate symptoms of the disorder.

33.7 percent of individuals with schizophrenia meet the criteria for alcoholism.

For people with co-occurring schizophrenia and substance addiction, specialized rehab programs treat the disorders together rather than independently, providing the best chance of recovery. Knowing the signs and symptoms of co-occurring schizophrenia and substance abuse is the first step to helping those with schizophrenia get healthy.

What Causes Schizophrenia?

Though the exact cause of schizophrenia is not known, a number of factors are believed to play a key role in the disorder’s development.

The dominant schizophrenia development factors include:
Schizophrenia runs in families. Schizophrenia occurs in less than 1 percent of the population; however, 10 percent of those with a first-degree relative with schizophrenia also develop the disorder. Individuals with second-degree relatives with schizophrenia also have higher rates of the disorder as well. Those with an identical twin who has schizophrenia have a 40 percent to 65 percent chance of developing the disorder.
Environmental factors are also believed to contribute to schizophrenia development. Exposure to viruses or chemicals in the womb, malnutrition before birth, complications during birth and psychosocial influences are possible factors for schizophrenia development. Individuals with older fathers are also at an increased risk of developing schizophrenia.
Brain Chemistry and Structure
Researchers believe that a chemical imbalance involving dopamine, glutamate and other neurotransmitters can contribute to schizophrenia development. Additionally, the brain structures of those with schizophrenia differ from those of healthy individuals. Ventricles — fluid-filled cavities at the brain’s center — are larger in individuals with schizophrenia. Individuals with schizophrenia usually have less gray matter, and some areas of their brains may have less or more activity than an average brain.
Drug Use
Mind-altering substance use during adolescence and young adulthood has been linked to schizophrenia, and substance use can speed the rate of schizophrenia development.

What Are Common Symptoms of Schizophrenia?

The onset of schizophrenia symptoms is usually not recognizable until late adolescence or early adulthood. Schizophrenia diagnoses are rare among children and individuals 45 or older. Schizophrenia typically occurs in males, although a good portion of schizophrenia cases are female.

Schizophrenia symptoms can be extremely debilitating, hindering an individual’s ability to function normally.

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Delusions from schizophrenia are strongly held false beliefs that are not based on reality or logic. Often, these delusions are characterized by paranoia and fear. Delusions are one of the most common symptoms of schizophrenia, as four out five individuals with schizophrenia experience them.

Examples of schizophrenic delusions include:
  • Irrational feelings of being harmed or harassed.
  • Belief that random or unrelated gestures and comments are directed at the schizophrenic individual.
  • False belief of having extraordinary abilities or powers.
  • Believing individuals are in love with them who are not.
  • Believing a major catastrophe is going to occur.


Schizophrenic hallucinations are characterized by seeing or hearing things that do not exist and believing they are real. Hallucinations can be through any of the senses; however, hearing voices is the most common hallucination.

Other hallucinations may include seeing people, objects or events that are not there, smelling odors that do not exist and feeling things such as an invisible finger when no one is present.

Disorganized Thinking

Disorganized thinking, usually manifested through disorganized speech, is a common side effect of schizophrenia. Disorganized thinking hinders schizophrenic individuals’ ability to effectively communicate.

They may give answers to questions completely unrelated to the topic or to questions never asked. They may also exhibit “word salad,” the term used to refer to combining words and thoughts in nonsensical fashion.

Abnormal Behavior

Symptoms of abnormal behavior can vary and may be hard to comprehend or recognize. Schizophrenic behavioral symptoms can range from acting irregularly childish to unpredictably agitated. Individuals exhibiting these symptoms may resist instructions, display odd or inappropriate posture or movements, fail to respond to verbal communication and exhibit other odd or irregular behaviors.

Negative Symptoms

Negative schizophrenia symptoms hinder the ability to function normally and rationally. They are often characterized by isolation and social withdrawal.

Negative symptoms include:
  • Lack of Emotion
  • Not Making Eye Contact
  • Not Changing Facial Expressions
  • Monotone Speech
  • Inability to Plan or Carry Out Activities
  • Speaking Less
  • Personal Hygiene Neglect
  • Loss of Interest
  • Lack of Ability to Experience Pleasure

Recognizing Teen Schizophrenia Symptoms

Discerning schizophrenia symptoms in teenagers can be difficult, as many symptoms are often associated with normal teen behaviors. Symptoms that could indicate schizophrenia or the potential development of schizophrenia include withdrawing from friends and family, poorer school performance, trouble sleeping, agitation, depression and a lack of motivation. Additionally, teens are less likely to exhibit delusion symptoms but are more likely to experience visual hallucinations.

Why Do People with Schizophrenia Abuse Drugs or Alcohol?

Substance abuse is the most common co-occurring disorder among people with schizophrenia. It is generally believed that individuals with schizophrenia use substances as self-medication to alleviate schizophrenic symptoms. The most commonly abused substances among those with schizophrenia are nicotine, alcohol, cannabis and cocaine, respectively.


More than 40 percent of the cigarettes smoked in the United States are smoked by individuals with a mental health disorder. In particular, schizophrenia is linked to incredibly high rates of smoking. According the National Institute on Drug Abuse, smoking rates among individuals with schizophrenia has ranged as high as 90 percent. A study cited in the American Journal of Psychiatry found that cigarette-smoking schizophrenic individuals were significantly more likely to be males and have an earlier onset of schizophrenia and a higher number of previous hospitalizations. According to studies cited by the U.S. National Library of Medicine, nicotine may alleviate cognitive deficiencies in schizophrenic individuals and is thought to be used to reduce the severity of schizophrenic symptoms; however, the negative health consequences from tobacco use outweigh the benefits for these individuals.


Alcohol addiction is the second most common co-occurring substance use disorder among people with schizophrenia. Alcohol is legal and widely available, making it an easy choice for individuals with schizophrenia. A study by the National institute for Mental Health’s Epidemiologic Catchment Area program found that 33.7 percent of those with schizophrenia or schizophreniform disorder (disorders with similar symptoms of schizophrenia that last less than six months) met the criteria for alcoholism at some point in their lives.


According to a study done by researchers at the University of Vienna, a growing amount of evidence from numerous studies shows that marijuana use may increase the odds of schizophrenia. Additionally, adolescents who use marijuana have twice the risk of developing schizophrenia or schizophreniform disorder in adulthood. Heavy cannabis use may also accelerate or exacerbate schizophrenic symptoms. A study cited in the Diagnostic and Statistical Manual of Mental Disorders found evidence that daily marijuana users had rates of psychotic symptoms 1.6 to 1.8 times higher than those of non-marijuana users.


Cocaine abuse among those with schizophrenia is linked to increased risks of suicide, high hospitalization rates, and noncompliance with substance use and mental health treatments. Researchers believe cocaine is used among individuals with schizophrenia to alleviate symptoms.

What are the Effects of Co-occurring Schizophrenia and Substance Abuse?

Schizophrenic individuals who abuse substances increase their likelihood of many negative consequences. They are more likely to relapse into psychosis, neglect their antipsychotic medications and other medical treatments, commit acts of violence and die by suicide.

They are also more vulnerable to injury and illness, poorer psychosis treatment outcomes and higher rates of inpatient and emergency services. Additionally, incarceration rates among those with co-occurring schizophrenia and substance use disorders are high.

Half of those with schizophrenia develop a substance use disorder in their lifetime.

Long-term substance abuse among those with schizophrenia can result in vast deterioration in functioning. Cannabis and alcohol abuse among those with schizophrenia is linked to psychotic relapse. Those with co-occurring substance abuse and schizophrenia also experience more frequent auditory hallucinations and paranoid delusions.

Overall, substance abuse among those with schizophrenia is linked to immense social, health and legal complications or consequences that can make it nearly impossible to live a healthy and productive life.

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How to Prevent Substance Abuse Among those with Schizophrenia?

While there is no absolute way to prevent schizophrenia, early treatment and recognition of symptoms can help control the development of the disorder and its severity, thus reducing the likelihood of developing a substance use disorder as well.

Compared to the general population, the odds of having a substance abuse diagnosis were found to be 4.6 times higher for people with schizophrenia.

Treatment programs for schizophrenia can help prevent relapse and the worsening of schizophrenia symptoms, as well as co-occurring disorders such as substance abuse. Additionally, eliminating schizophrenia risk factors can also prevent substance abuse.

Reducing stressors for individuals with schizophrenia can prevent negative symptoms, relapse and substance use. According to a study by researchers at Emory University, stressors increase substance use and can exacerbate schizophrenia symptoms. Implementing prevention techniques that eliminate stress among those with schizophrenia may also reduce substance addictions in this population.

Treatment and Recovery for Co-occurring Schizophrenia and Substance Addiction

Treatment for co-occurring schizophrenia and substance use disorder is most effective when it is integrated to manage the disorders together rather than independently. Co-occurring disorder treatment programs give individuals the greatest chance of recovery.

Many co-occurring disorder programs use a technique called behavioral treatment for substance abuse in serious and persistent mental illness (BTSAS) to reduce substance abuse in those with schizophrenia and other mental illnesses.

BTSAS key treatment strategies include:
  • Urinalysis Contingency
  • Setting Short-Term Goals
  • Psychoeducation
  • Developing Substance Refusal Skills
  • Relapse Prevention Training

If you or someone you know has schizophrenia, or you recognize schizophrenic symptoms in your own or another’s behavior, there are options to help prevent the disorder from worsening and prevent the development of a substance abuse disorder. The earlier a schizophrenic individual receives treatment, the better chance that person has to reach recovery.

Medical Disclaimer: aims to improve the quality of life for people struggling with a substance use or mental health disorder with fact-based content about the nature of behavioral health conditions, treatment options and their related outcomes. We publish material that is researched, cited, edited and reviewed by licensed medical professionals. The information we provide is not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be used in place of the advice of your physician or other qualified healthcare provider.

Trey Dyer
Content Writer,
Trey Dyer is a writer for and an advocate for substance abuse treatment. Trey is passionate about sharing his knowledge and tales about his own family’s struggle with drug addiction to help others overcome the challenges that face substance dependent individuals and their families. Trey has a degree in journalism from American University and has been writing professionally since 2011.

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