Schizophrenia is an incurable, yet treatable, chronic brain disorder that affects a person’s ability to think, feel, and behave clearly. More than 21 million people worldwide are affected by the disease. Research has discovered numerous correlations between schizophrenia and substance abuse disorders.

This co-occurrence has been a heavily debated topic for decades. Most researchers feel substances such as drugs and alcohol do not cause schizophrenia; instead, people living with mental illness use substances as a coping mechanism. However, some researchers have also concluded that it could occur the other way around and have found that substance abuse can increase the risk of developing schizophrenia.

This particular type of psychosis can have many of the same symptoms as an addiction. This can make a diagnosis of both conditions difficult and can even hamper a person’s recovery from these disorders. Luckily, Vertava Health has several behavioral health treatment facilities that specialize in treating co-occurring disorders such as schizophrenia and addiction.

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What Is Schizophrenia?

Schizophrenia is a serious mental disease that often causes individuals to experience irrational or delusional thinking. Doctors typically describe schizophrenia as a type of psychosis, as this condition can often make a person unable to distinguish their thoughts and ideas from reality.

People that have schizophrenia may display signs of paranoia and psychosis. They often will hear voices in their heads or see things that do not exist. Sufferers may also have drastic back-and-forth changes in behavior, becoming upset, anxious, confused, angry, or suspicious in short periods of time.

Many with schizophrenia believe they do not need help. This can not only present problems in a person seeking treatment but is also one reason a sufferer may turn to substances as a way to cope.


Like substance use disorders, mental illness does not discriminate. Schizophrenia can occur despite age, race, gender, social status, or family history. However, it is slightly more common in males than females, and onset is most prevalent in adolescent years or early adulthood.

When active, schizophrenia changes how a person thinks and behaves. The disease typically develops slowly and often begins during the teenage years, which can make it hard to identify since these symptoms can mimic other common adolescent behaviors.

Severity, frequency, and duration of symptoms can vary, but there are some common signs. Not taking medications as prescribed, using drugs or alcohol, and high stress tends to increase symptoms of this condition.

Common symptoms of schizophrenia include:

  • Disorganized Thinking — A person may have trouble keeping track of thoughts, become easily confused, have a low attention span, poor logical thinking, give answers to questions not asked or utterly unrelated to the topic at hand, experience a decline in educational performance, and put words together that do not make sense.
  • Abnormal Motor Behavior — This may present in several ways. Acting extremely childlike, unpredictable agitation, resistance to instructions, and useless or excessive movements are all very common.
  • Hallucinations — These can affect any of the senses. A person may hear or see things that don’t exist. Hearing voices is the most common form of hallucinations.
  • Delusions — These are false or unusual beliefs that are not reality. For example, a sufferer may be convinced that a major catastrophe is about to occur, that someone is going to harm them, or that they are of celebrity status.
  • Changes In Everyday Behaviors — A person may neglect personal hygiene, lose interest in daily activities, come across as emotionless (speaks in a monotone voice, makes no eye contact, and has few facial expressions), and be socially withdrawn.
  • Violence — Some people think schizophrenia causes a “split personality” or violent behavior. This is not typically the case. The cause of violent action is usually a result of the co-occurrence of drug or alcohol abuse.

Causes Of Schizophrenia

The exact cause of schizophrenia is unknown. However, genetics, environmental factors, and altered brain chemistry are all documented as potential causes.

  • Genetics — Scientists have yet to pinpoint a specific gene that causes schizophrenia. They believe that many different genes increase risk. It has long been known that schizophrenia runs in families; however, this does not mean that someone with a strong family history of the condition will develop the disorder.
  • Environment — Scientists have found a correlation between genes and certain environmental factors such as exposure to viruses, malnutrition before birth, and problems with brain development before birth.
  • Brain Chemistry — Scientists believe that an imbalance involving certain neurotransmitters often plays a role in the development of schizophrenia.

Experts continue to examine potential causes of the disease by performing behavioral research, studying genetics, and using advanced imaging to explore the brain’s structure and function.

The Connection Between Schizophrenia And Addiction

People with schizophrenia are up to four times more likely to be diagnosed with substance addiction compared to the general population.

The co-occurrence of substance abuse and schizophrenia most often occurs with the mental illness coming first and substance abuse coming second. Commonly, someone with schizophrenia begins using an addictive substance to deal with the symptoms of this condition. This is very dangerous because even moderate use of substances can exacerbate many of the symptoms of schizophrenia.

Researchers have also found the opposite to be true. Statistics show that over half of all people with schizophrenia abused at least one substance before the onset of the disease.

Some substances appear to carry a higher risk than others. Cannabis, alcohol, and nicotine seem to be sited the most.


Statistics show that 53 percent of people experiencing their first episode of psychosis abused marijuana beforehand. Most researchers conclude that cannabis does not cause schizophrenia. They believe the connection is likely because sufferers are using the drug to self-medicate, unaware that cannabis has been proven to do the opposite and enhance the severity of schizophrenia symptoms.

However, one large study did find that marijuana use significantly contributed to the onset of schizophrenia due to a biological interaction between chemicals in marijuana and chemicals in the brain. Several other significant studies also found that teens under the age of 15 that use cannabis regularly are up to four times more likely to develop schizophrenia by their late 20’s.


Because alcohol is legal and easy to obtain, it is easy for someone to attempt to cope with mental illness with excessive drinking. Statistics show that almost one-third of people with schizophrenia develop an alcohol use disorder. However, researchers have also discovered that alcohol abuse can precede schizophrenia, which means that their self-medication theory is not always the case.


Research shows that a large number of people that suffer from schizophrenia smoke regularly. They discovered this might cause sufferers to have more frequent episodes of hallucinations, delusions, or disorganized speech. Those addicted to nicotine also seem to require higher doses of antipsychotic medications.

Experts believe that no matter the addiction, substance abuse creates a higher chance of relapse in those recovering from an active schizophrenic episode.

It is also important to note that not every person suffering from addiction who displays schizophrenic symptoms is also dealing with schizophrenia. Many of the signs of substance abuse will mimic schizophrenic behaviors. This does not mean the substance abuse sufferer has a mental disorder. They need to be examined by a doctor to receive a proper diagnosis.

Effects Of Co-Occurring Disorders:  Substance Abuse And Schizophrenia

If a person with schizophrenia develops an addiction to substances, he or she is more likely to stop taking medications and other forms of treatment for schizophrenia. Substance abuse can also worsen many of the characteristics that someone with schizophrenia exhibits. When the two are mixed, it can lead to a dangerous spiral and relapse of psychosis. They are also more likely to self-harm, be violent, or become incarcerated.

Schizophrenia And Addiction Treatment Centers

According to a 2014 National Survey on Drug Use and Health, 7.9 million people in the U.S. experience a mental disorder and substance use disorder simultaneously. The best treatment for co-occurring disorders is an integrated approach where a person receives care for both substance abuse and the diagnosed mental illness at the same time.

The first step in the situation of substance abuse and schizophrenia would typically be detox. This addresses withdrawal symptoms and also allows doctors to ensure the psychotic symptoms are not just a side effect of addiction and that schizophrenia is indeed medically present.

If medical professionals diagnose schizophrenia, there will then need to be a focus on eliminating the symptoms of the disease. Frequently this is done with antipsychotic medications.

After each issue is diagnosed correctly, and initial medical treatment is complete, a full treatment plan can begin. Inpatient rehab, where someone can receive 24/7 care, is the best approach.

The exact treatment plan will not be the same for everyone, but will likely include various forms of individual, behavioral, family, and group therapy.

If you or someone you know is suffering from co-occurring substance abuse and schizophrenia, we would love to help educate you about our integrated treatment programs. Reach out to one the Vertava Health’ compassionate and fully trained treatment specialists as soon as possible.

Suicidal thoughts and behaviors are common among people with schizophrenia, and substance abuse can enhance these feelings. If you have a loved one who is in danger of attempting suicide or has made a suicide attempt, do not leave the person alone and call 911 immediately.