Nicotine could have a beneficial effect on the symptoms of schizophrenia
Mar 3, 2005 - 6:04:38 PM
A new study has suggested that nicotine could have a beneficial effect on the symptoms of schizophrenia among mildly dependent smokers. However, people with schizophrenia who have high nicotine dependence are more likely to be readmitted to hospital and have a poor outcome.
Published in the March issue of the British Journal of Psychiatry, the study set out to explore the hypothesis that smoking is a form of 'self-medication' for people with schizophrenia.
Worldwide, schizophrenia is associated with a higher rate of smoking than that observed in the general population, or among those with other severe mental illnesses.
Although it has been suggested that smoking may have a beneficial effect on either schizophrenic symptoms, or on the side effects of antipsychotics drugs, research so far has been hampered by confounding factors, such as medication, or alcohol and drug use.
The study was carried out in two community mental health centres in Granada in Spain. 250 patients diagnosed with schizophrenia were classified into three categories: highly dependent smokers, mildly dependent smokers and non-smokers.
'Positive' symptoms of schizophrenia (e.g. delusions and hallucinations) and 'negative' symptoms (e.g. withdrawal and depression), and the number of admissions to hospital, were compared between the three groups.
69% of the patients studied were current smokers. It was found that high total and positive symptom levels were less frequent in mildly dependent smokers than in non-smokers or in highly dependent smokers. This finding supports the self-medication hypothesis for these symptoms in this group of patients.
Negative symptoms were not significantly associated with nicotine dependence, however, and so the self-medication hypothesis is not borne out in this respect.
Highly dependent smokers had the highest proportion of hospital admissions compared with mildly dependent smokers and non-smokers.
The authors of the study comment that the findings do not generally support the self-medication hypothesis, but rather suggest a complex interaction between nicotine dependence and the symptoms of schizophrenia.
If there is any beneficial effect of nicotine, it may be restricted to mildly dependent smokers, and particularly to those on low dosages of typical antipsychotics who are sensitive to the side effects of these older types of drug.
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