Nicotine dependence and symptoms in schizophrenia: naturalistic study of complex interactions.
BACKGROUND
Smoking may have a beneficial effect on either schizophrenic symptoms or antipsychotic side-effects, but studies are hampered by the lack of control of confounding factors.


OBJECTIVE
To explore the self-medication hypothesis in a large sample of stable out-patients with schizophrenia.


METHODS
Symptoms, assessed with the Positive and Negative Syndrome Scale (PANSS), and number of hospitalisations were compared in 250 out-patients with DSM-IV schizophrenia classified into three categories: highly dependent smokers, mildly dependent smokers and non-smokers. Log-linear analysis was used to control for potential confounding and interacting variables.


RESULTS
High PANSS total scores and positive symptoms were less frequent in mildly dependent smokers than in non-smokers or highly dependent smokers. The highly dependent smokers had the worst outcome.


CONCLUSIONS
The data do not generally support the self-medication hypothesis but rather suggest a complex interaction between nicotine dependence and nicotine dependence and schizophrenic symptoms.
Aguilar
M Carmen
MC
Department of Psychiatry and Institute of Neurosciences, Faculty of Medicine, University of Grenada, Av. Madrid 11, E-18071 Granada, Spain.
Gurpegui
Manuel
M
Diaz
Francisco J
FJ
de Leon
Jose
J
D000328:Adult; D017831:Diagnosis, Dual (Psychiatry); D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D011379:Prognosis; D011569:Psychiatric Status Rating Scales; D012565:Schizophrenic Psychology; D012651:Self Medication / Q000523:psychology; D014029:Tobacco Use Disorder / Q000523:psychology*