Smoking and schizophrenia.
Smoking prevalence for schizophrenic patients is higher than this for general population. More than 60% of schizophrenic patients are current smokers, which contributes to excessive mortality in these patients. The reasons for high frequency of both smoking prevalence and heavy smoking in schizophrenic patients is thought to be at least partially related to enhancement of brain dopaminergic activity, which, in turn, results in behavioral reinforcement due to stimulant effects. Smoking stimulates dopaminergic activity in the brain by inducing its release and inhibiting its degradation. There is also evidence that cigarette smoking can reduce deficits relative to dopamine hypofunction in prefrontal cortex. Recent neuroimaging studies have further contributed the evidence of complex influences of cigarette smoking on brain dopaminergic function. It has been suggested that smoking may be an attempt by schizophrenic patients to alleviate cognitive deficits and to reduce extrapyramidal side-effects induced by antipsychotic medication. Cigarette smoke also increases the activity of CYP 1A2 enzymes, thus decreasing the concentration of many drugs, including clozapine and olanzapine. There is also evidence that smoking is associated with increased clearance of tiotixene, fluphenazine and haloperidol. Given the high frequency of smoking in schizophrenic patients, clinicians need to check smoking status in each patient. Schizophrenic patients who smoke may require higher dosages of antipsychotics than nonsmokers. Conversely, upon smoking cessation, smokers may require a reduction in the dosage of antipsychotics.
University Department, Clinical Hospital Zagreb, 10000 Zagreb, Croatia. weekend@paris.hr
Marina
M
Sagud
Alma
A
Mihaljević-Peles
Dorotea
D
Mück-Seler
Nela
N
Pivac
Bjanka
B
Vuksan-Cusa
Tomo
T
Brataljenović
Miro
M
Jakovljević
D014150:Antipsychotic Agents / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use; D001921:Brain / Q000503:physiopathology; D015897:Comorbidity; D003430:Cross-Sectional Studies; D019388:Cytochrome P-450 CYP1A2 / Q000502:physiology; D004298:Dopamine / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008657:Metabolic Clearance Rate / Q000502:physiology; D012559:Schizophrenia / Q000188:drug therapy / Q000453:epidemiology* / Q000503:physiopathology; D012565:Schizophrenic Psychology; D012907:Smoking / Q000453:epidemiology* / Q000503:physiopathology / Q000523:psychology; D016540:Smoking Cessation
D014150:Antipsychotic Agents; C504573:CYP1A2 protein, human; D019388:Cytochrome P-450 CYP1A2; D004298:Dopamine