Schizophrenia and Addiction: Is Schizophrenia Linked to Substance Abuse?

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Understanding Schizophrenia

Schizophrenia is a serious mental illness that affects how a person thinks, feels, and behaves. People with schizophrenia may have delusions, hallucinations, disorganised speech, a lack of motivation, and trouble thinking. The symptoms of schizophrenia can make it difficult to participate in everyday life, but effective treatments are available. 

Schizophrenia is complex and there are many misconceptions about the disease due to media representation and discrimination. Living with schizophrenia does not mean someone has a split personality or multiple personalities, and/or is more dangerous than people without the illness. 

What Are Co-occurring Disorders?

Co-occurring disorders — which may also be referred to as dual diagnosis, COD, or dual pathology — is a common and complex condition that describes someone having a concurrent mental illness and substance use disorder. Co-occurring disorders describe a combination of mental health concerns: depression and alcohol use disorder; severe mental illness such as schizophrenia and cocaine misuse; or milder mental illness like anxiety and a dependency on sedatives.

Diagnosing psychiatric illness in those who use mood-altering substances is challenging as substance use can often induce psychiatric symptoms. It is, therefore, necessary to differentiate between substance-induced and pre-existing mental illness. This is only achieved when the person struggling with a substance use disorder stops the use of all addictive substances.

Without a careful diagnosis, the efficacy of personalised treatment plans is compromised. For example, depression that is separate in origin from drug misuse may require specific medication and specifically focused psychotherapy. If misdiagnosed, drugs and therapy may be ineffectual and perhaps prevent someone from fully recovering, leading to relapse. 

Those with co-occurring disorders face complex challenges. They have increased rates of relapse, hospitalisation, and homelessness compared to those with either singular mental or substance use disorders.

schizophrenia and addiction

Schizophrenia Symptoms and Effects

Schizophrenia is characterised by episodes in which someone is unable to distinguish between real and unreal experiences. The severity, duration, and frequency of symptoms vary and include the following: 

  • Psychosis — loss of touch with reality due to how the brain processes information. A psychotic episode is a disturbance in someone’s thoughts and perceptions. As such, they find it difficult to understand what is real and what is not real
  • Hallucinations — hearing, seeing, smelling, tasting, or feeling things that are not there. Hallucinations are vivid and mirror normal perceptions
  • Delusions — holding false beliefs despite evidence that they are untrue. Paranoid delusions are when someone believes they are being harmed or harassed 
  • Confused thinking and speech — thoughts and speech that do not make sense. Someone may switch from one subject to another or respond to a question with an unrelated answer
  • Abnormal movements and/or behaviour — childlike, unpredictably agitated, or repeated movements. Severe, abnormal movements related to schizophrenia can cause problems in daily life
  • Catatonia — a dazed state with little movement or response to surroundings

While there is no cure for schizophrenia, with the proper treatment most symptoms of schizophrenia will greatly improve and the likelihood of a recurrence can be diminished.

Brain Structure and Chemistry

Schizophrenia is associated with changes in the structure and functioning of the brain. In MRI studies of schizophrenia, the most consistent findings include the following:

  • Reduced grey matter in areas of the brain that affect memory, processing of auditory information, short-term memory and decision-making. These grey matter deficiencies have been shown to be partially hereditary
  • Brain surface contraction possibly plays a role in the onset of schizophrenia symptoms
  • Disrupted white matter has been implicated in disordered communication between brain regions and the subsequent onset of schizophrenia symptoms

Genetic Underpinnings of Schizophrenia and Co-occurring Substance Use Disorder

Evidence that schizophrenia is inherited has come from twin studies as identical twins share the same genes. In identical twins, if a twin develops schizophrenia, the other twin has a high (one in two) chance of developing the illness, even if raised separately. In non-identical twins who have different genes, when a twin develops schizophrenia, the other has a much lower (one in eight) chance of developing the illness. However, as yet, no particular gene for schizophrenia has been found. Combinations of genes may make people more vulnerable to the condition.

Living with Schizophrenia and Cocaine Addiction

The high prevalence of substance abuse in schizophrenia demonstrates the link between the use of substances and the development of psychoses. Apart from alcohol misuse, cocaine is one of the most commonly abused substances by those with schizophrenia. Cocaine use during psychosis is associated with increased psychotic symptoms and poorer treatment outcomes. Since both substance use disorder and schizophrenia have been observed to be closely interdependent, a particular treatment for schizophrenic patients with cocaine abuse issues is needed to provide effective care. 

Those with schizophrenia and cocaine addiction are at an increased risk of: 

  • illness and injury;
  • impaired cognitive functioning during intoxication;
  • needing inpatient treatment and care from the emergency services;
  • Incarceration; and
  • lack of stable housing.

Treating the Different Types of Schizophrenia and Addiction

A range of treatments for co-occurring schizophrenia and addiction are available. Schizophrenia must be treated with an individually-tailored combination of talking therapy and medicine as schizophrenia can present very differently from person to person. Co-occurring disorders should be treated concurrently in one setting with one consistent message to ensure positive treatment outcomes and prevent relapse. 

Types of Treatment Options Available 

The goals of treating co-occurring schizophrenia are targeting symptoms, preventing relapse, and increasing adaptive functioning so that clients can be integrated back into their community. Treatment involves a combination of pharmacological (medication) and nonpharmacological (psychotherapy) interventions. 


Most people with schizophrenia who are struggling with an addiction will find it difficult to recover from that addiction without the appropriate medication to treat the symptoms of schizophrenia. As such, prompt medical treatment is vital to return clients to normal functioning — such as eating and sleeping — before addiction treatment can begin.

Maintenance medical therapy for schizophrenia aims to increase socialisation, support self-care, and improve mood which in turn helps with addiction recovery and prevents relapse.

Antipsychotic medications are the most commonly prescribed for schizophrenia. These medications alter levels of dopamine and serotonin which affect mood, movement, and the way a person responds to rewards. Antipsychotic medications help reduce hallucinations and psychotic episodes which can also reduce the risk of substance abuse relapse.  

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Medication is the mainstay of schizophrenia management, but residual symptoms that persist can be managed through psychotherapy. Psychotherapy is also the main treatment approach for addiction. 

Psychotherapeutic approaches for schizophrenia and addiction include individual, group, cognitive behavioural, and compliance therapy. Therapy can help educate patients about the importance of taking their medications, without which they might be hospitalised or relapse. Talking therapies for schizophrenia focus on helping people cope with symptoms, rather than trying to convince them that their beliefs or experiences are wrong.

Therapy for those recovering from schizophrenia and addiction aims to help them: 

  • cope with symptoms of psychosis such as delusions or hearing voices
  • reduce stress so symptoms don’t become more intense
  • manage any side effects from medication
  • cope with social anxiety and depression
  • experience continued free form from substance misuse

Treatment programs for those with schizophrenia and addiction that encourage family support have been shown to decrease rehospitalisation, improve social functioning, and prevent relapse. Family therapy can inform family members on how to monitor their loved ones and when to report the adverse effects of treatment to clinicians. 

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If you are worried about yourself or a loved one and would like to discuss treatment for addiction alongside schizophrenia, please contact our team to find out how our treatment programme can help. 


Are schizophrenia medications addictive?

Most medications for schizophrenia are non-habit-forming. These medications alleviate symptoms and improve health but do not induce craving and the outcome of use is positive.

Do schizophrenics have higher rates of substance use disorders?

According to the medical journal Schizophrenia Bulletin, the rate of substance misuse disorders is 50% higher among individuals with schizophrenia than among the general population. 

What substance misuse do patients with schizophrenia have?

Up to 50% of patients with schizophrenia exhibit either alcohol or illicit drug dependence, and more than 70% are nicotine dependent. In particular, heavy cocaine and cannabis abuse have been reported to be a stressor, eliciting relapse in patients with schizophrenia and related disorders.

What are the coping styles of schizophrenia?

The term “coping” describes conscious and unconscious ways in which people deal with stress. Coping styles of schizophrenia include control, denial, social support, avoidance, self-accusation, diversion, and underestimation. 

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