Schizophrenia and Substance-Related Disorders

schizophreniaSchizophrenia, characterized by positive symptoms, such as delusions, hallucinations, disorganized speech, and negative symptoms, such as blunted affect, reduced motivation, and poor social relationships, affects approximately one percent of the population.[1]

Approximately 50 percent of individuals with schizophrenia have a comorbid lifetime substance use disorder, commonly addicted to tobacco and cannabis.1 With schizophrenia, the presence of a substance use disorder is associated with alterations in neurocognitive performance.1

Nicotine and Tobacco

Individuals with schizophrenia are more likely to smoke cigarettes and often begin at a younger age.1 They tend to extract more nicotine from each cigarette and have a preference for higher-tar brands.1 One hypothesis suggests that individuals with schizophrenia smoke to alleviate negative symptoms by improving a dysfunctional dopamine system.1 Also, another hypothesis further adds that genetic and neurobiological factors associated with schizophrenia, such as alterations in nicotine acetylcholine receptors and central dopamine systems may actually predispose schizophrenia patients to nicotine addiction.1

A recent study by Wing and colleagues found that smoking history and current smoking status was associated with neurocognition in individuals with schizophrenia.1 In fact, patients without a history of nicotine and tobacco use actually performed worse than those who did use nicotine and tobacco on neurocognitive tasks that assess processing speed, attention, and response inhibition.1

Sacco and colleagues conducted a study on smoking abstinence on visuospatial working memory in individuals with schizophrenia and found that there were significant impairments.1 Abstinence specifically impaired visuospatial working memory, but were restored after smoking began again.1

Both studies found that cigarette smoking may actually enhance visuospatial working memory and attention in individuals with schizophrenia.1 However, using nicotine and tobacco are not healthy ways of treating symptoms of schizophrenia, and more studies are needed on these topics.1


Individuals with schizophrenia have high rates of cannabis use disorder, with a lifetime prevalence of 13 to 64 percent.1 Studies have shown that there is an increased risk of schizophrenia and psychotic symptoms following heavy cannabis use.1 In fact, cannabis misuse often occurs before the onset of psychosis and cause the symptoms to worsen over time.1

Surprisingly, some studies have shown that despite the worsening symptoms, cannabis actually increases neurocognitive performance.1 Still, this is counterintuitive as cannabis has been shown to deteriorate neurocognitive performance over time in individuals with schizophrenia.1 A closer look at this association is warranted.1

Schnell and colleagues conducted a study to see the impact of cannabis use on neurocognition in a large sample of individuals with schizophrenia.1 The group who used cannabis performed better on tests of verbal and working memory, visuomotor speed, and executive function.1 However, individuals with schizophrenia who use cannabis may possess essential skills required to communicate with drug dealers and negotiate within the subculture required to get illicit drugs, traits that have been associated with higher neurocognitive capacities among those with schizophrenia.1

Future Research

Therapies that target the nAChRs, which mediate the reinforcing properties and neurocognitive effects of nicotine in smokers may have therapeutic effects on neurocognitive dysfunction in individuals with schizophrenia.1 Also cannabinoid antagonists or partial agonists may improve neurocognition in these individuals.1 Further research on such treatments are needed, as using the real substances pose other significant health issues.1

[1] Sharif-Razi, M., Rabin, R., & George, T. (2013, October 14). Schizophrenia, Neurocognitive Dysfunction, and Substance-Related Disorders: A Review. Psychiatric Times. Retrieved November 14, 2013, from http://www.psychiatrictimes.com/schizophrenia/schizophrenia-neurocognitive-dysfunction-and-substance-related-disorders-review/page/0/1

One Comment

  • Yamileth

    November 21, 2013, 1:19 am

    This hit home. My daughter has schizophrenia with psychosis.

Leave a Reply

Your email address will not be published. Required fields are marked *

We are the only facility in Florida owned and operated by an addiction psychiatrist involved in all treatment decisions. Learn more
Hello. Add your message here.