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Why do so many schizophrenic patients smoke?

NOTE: for additional information on schizophrenia and Smoking or Nicotine

Why do schizophrenic patients smoke?

Persons with serious mental illness, especially schizophrenia, smoke at much higher rates (45% to 88%) than those without mental illness (23%). Patients with schizophrenia also have a harder time in quitting smoking. Researchers have found this when they looked at abstinence rates in smoking cessation trials using nicotine replacement patches (36% to 42% abstinence in schizophrenia) and bupropion (11% to 50% abstinence in schizophrenia). In comparision, non-psychiatric smokers have higher abstinence rates at the end of such trials (50% to 75%). Below are two studies that were published this month, that discuss why this may be.

The German article (Cattapan-Ludewig et al) reviews studies that discuss why individuals with schizophrenia smoke chronically. Certain thinking patterns are affected in schizophrenia including sustained attention, focused attention, working memory, short-term memory, recognition memory and even processes that are preattentive (eg reflexes). Some studies have suggested that there may be improvements in these areas after treatment with nicotine. So, it maybe that nicotine is used as a "self-medication" strategy by those with schizophrenia to improve these difficulties with attention, cognition, and information processing as well as the side effects of antipsychotic medications (eg extrapyramidal effects).

The second recent study (Dolan et al) specifically looked at what happens if a smoking cessation intervention is used. They investigated whether the presence of these cognitive problems prior to smoking cessation treatment was associated with smoking cessation treatment failure in schizophrenia as compared to non-psychiatric control smokers. They looked at performance on neuropsychological tests of thinking, planning, visual-spatial skills and attention.

After going through the smoking cessation program, those with schizophrenia who initially had more difficulity with visual-spatial skills, thinking and planning prior to the starting the program, were significantly less likely to quit smoking. This was not true for controls.

Interestingly, they also found that differences between quitters and non-quitters were not likely to be related to the medications or depressive symptoms. Previous work has shown that treatment with atypical antipsychotic medications can reduce smoking behaviors in schizophrenics, so in this study the relationship between impaired baseline neuropsychological test performance and smoking cessation outcome was not likely related to improvements produced by the medications.

They conclude from these results that in schizophrenia, neuropsychological problems are associated with smoking cessation treatment failure. There are parts of the brain that are affected in schizophrenia (eg prefrontal cortex or PFC) that control certain chemicals (eg dopamine). Based on the results here, it maybe that patients "self medicate" to remediate the chemical imbalance in the brain (dopamine hypofunction in the PFC) which may help with certain difficulties with thinking tasks involving this PFC area and might explain why there is smoking persistence in schizophrenia. With the higher risk of nicotine addiction in schizophrenia, comes a greater risk for the development of smoking-related medical problems and mortality. So, it becomes important to develop improved methods for smoking cessation in schizophrenia.

In terms of clinical interventions, the authors suggest that programs aimed at remediating PFC-related neuropsychological deficits may assist patients in efforts to quit smoking, especially for those with more severe difficulites. The authors report that there are mixed findings about the impact of medications on these cognitive problems. Some have found that risperidone can improve spatial working memory deficits, others have found that clozaril helps with psychomotor speed, attention, verbal fluency & executive thinking, while olanzapine may also help with thinking and planning. The authors also discuss other non-medication based interventions such as Neurocognitive Enhancement Therapy and Cognitive Remediation Therapy which involve intensive practice of skills found to be deficient in schizophrenia.

There are several limitations of their study including small sample size, the use of two separate clinical trials with different pharmacological smoking cessation interventions (bupropion in schizophrenia patients and selegiline in controls), lack of long term evaluation, multiple statistical comparisons, no measure of pre-trial IQ, and smoking deprivation.

Sources:

Why do Schizophrenic patients smoke?
Cattapan-Ludewig K, Ludewig S, Jaquenoud Sirot E, Etzensberger M, Hasler F.Nervenarzt. 2004 Sep 23.

Neuropsychological deficits are associated with smoking cessation treatment failure in patients with schizophrenia.Schizophr Res. 2004 Oct 1;70(2-3):263-75.
Dolan SL, Sacco KA, Termine A, Seyal AA, Dudas MM, Vessicchio JC, Wexler BE, George TP.

Click here to find the first article on PubMed

Click here to find the second article on PubMed

NOTE: for additional information on schizophrenia and Smoking or Nicotine

Author: Farzin Irani