The impact of new research into schizophrenia on individuals with dual diagnosis - Sovereign Health Group
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05-06-16 Category: Dual Diagnosis, Research

new research into schizophrenia on individuals with dual diagnosis

Earlier this year, researchers discovered a genetic variation peculiar to people with schizophrenia. The possibility of an underlying organic cause for the disorder could lead to more precise treatment. But this development may not be any consolation to individuals with co-occurring schizophrenia and a substance abuse disorder.

Complement component 4 and SETD1A

Scientists have long known schizophrenia is inheritable. But until recently, they have been unable to pinpoint where the abnormalities appear in an individual’s genetic makeup. Identifying variations in complement component 4 (C4) genes and loss of function in SETDIA genes has provided researchers with the chromosomal jumping off point from where they can trace the etiology of the disorder. But a review of the literature reveals nothing substantial with respect to individuals with co-occurring schizophrenia and substance abuse disorders (SUDs).

SUDs and schizophrenia

The Epidemiologic Catchment Area (ECA) study, conducted by the National Institute of Mental health between 1980 and 1983, was unprecedented in scale. Over the course of the study, researchers conducted over 20,000 interviews with individuals with mental health issues, SUDs or both. The study found 37 percent of individuals with alcohol disorders and 53 percent with drug disorders had co-occurring psychiatric problems. Individuals with schizophrenia were three times more likely to abuse alcohol and six times more likely to abuse drugs compared to individuals without schizophrenia. On a related note, over 70 percent of individuals with schizophrenia smoked and 40 percent of these smoked over 40 cigarettes a day.

Reasons why individuals with schizophrenia have high rates of substance abuse

Researchers at the University of Manchester developed four hypotheses for why individuals with schizophrenia have higher-than-average rates of substance abuse:

  • Substance abuse causes schizophrenia. There is insufficient evidence to establish a cause-and-effect relation between substance abuse and mental illness, but a landmark study that followed 45,000 Swedish soldiers for 15 years does lend credence to the connection between extensive marijuana use and the onset of schizophrenia.
  • People with schizophrenia self-medicate with substances in order to deal with their condition.
  • SUDs and schizophrenia share etiological factors.
  • Schizophrenia and SUDS have a symbiotic relationship.

Of the four, researchers considered the second hypothesis as the most likely. They looked at 11 studies that examined substance abuse among individuals with psychosis. They found in the majority of these studies, the individuals self-medicated to alleviate depression, anxiety, boredom or simply to relax. They also used alcohol and drugs to improve socialization skills.

Mental illness then substance abuse (or vice versa)

One explanation for why researchers have not extrapolated their genetic variation findings to SUDs is that in the majority of cases involving dual diagnosis, mental illness developed before substance abuse. But they also note in a study involving cannabis and schizophrenia, 23 of 24 patients reported a history of cannabis use prior to the onset of their schizophrenia.

In their study, the Manchester researchers concluded that studying this chicken-or-egg dynamic in individuals with schizophrenia is extremely difficult because SUDs and schizophrenia typically develop slowly after adolescence. A myriad of factors can affect the pathologies of both conditions.

The Sovereign Health Group specializes in treating individuals with dual diagnosis. As the above shows, mental illness and SUDs are often interwoven. Our treatment programs treat the conditions and the underlying factors that cause them. Contact our helpline to learn more about our dual diagnosis and other programs.

About the author:

Darren Fraser is a content writer for Sovereign Health Group. He worked two and half years as reporter and researcher for The Yomiuri Shimbun until they realized he did not read, speak or write Japanese and fired him. Undeterred, he channels his love of research into unearthing stories that provide hope to those dealing with addiction and mental illness. Darren loves the Montreal Canadiens hockey club and horror films and would prefer to enjoy these from the comforts of his family’s farm in Quebec. For more information about this media, contact the author at

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