Abstract
BackgroundNicotine use is higher among patients with schizophrenia (50–98%) than in general population (25–30%). This association can reflect a non-specific liability to substance use or specific effects of tobacco on symptoms severity or side effects. Studies about nicotine use and schizophrenia symptoms dimensions are controversial. Some of them showed a relation between severe nicotine use and higher positive symptoms and others presented a correlation between lower negative symptoms and nicotine use. That is why we aimed to verify whether nicotine use is associated with symptoms dimensions in patients with schizophrenia.MethodsTwo hundred and seven outpatients were enrolled from the Programa de Esquizofrenia da Universidade Federal de São Paulo (PROESQ/UNIFESP). Schizophrenia diagnosis was confirmed by Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I). Dimensional psychopathology was assessed with Positive and Negative Syndrome Scale (PANSS) and Fagerstrom Test for Nicotine Dependence. The PANSS items were grouped in five dimensions: positive, negative, disorganized/cognitive, mood/depression and excitement/hostility. The total score of Fagerstrom Test for Nicotine Dependence was the index used for severity in nicotine dependence. We used Wilcoxon-mann- whitney test to compare the means of PANSS dimensions between nicotine users versus non nicotine use.ResultsThe patients mean age was 36.75 (SD 10.648), 69.1% were male, 48.3% reported lifetime tobacco use and 34.3% reported current tobacco use. Lower scores on negative dimension were associated with nicotine use (W = 5642.5, p-value = 0.046, effect size = 0.446). All p-values were corrected by Bonferroni test. Tests that evaluated the relationship between nicotine use and the total PANSS score or other dimensions were not statistically significant.DiscussionThis study shows that nicotine use impacts negative symptoms of schizophrenia. Increase in hepatic metabolism leading to low antipsychotic blood levels has been previously documented in patients with schizophrenia. Thus, the observed results can either indicate effect on primary negative symptoms or indirect effects through reduced D2 blockade caused by lower antipsychotic levels. Future quantitative analyzes and Longitudinal studies may better inform on direction of the association between nicotine dependence and negative symptoms in schizophrenia.
Highlights
Long-term use of cannabis has long been associated with changes in cognition, including memory and learning, verbal learning in man
We aimed to investigate the relationship between substance use and early abstinence and the long-term course of illness in a representative sample of first-episode psychosis (FEP) patients
There was no significant difference in total recall score between cannabis users (CU) and non-using controls (NU)
Summary
Long-term use of cannabis has long been associated with changes in cognition, including memory and learning, verbal learning in man. Methods: We aimed to investigate the relationship between substance use and early abstinence and the long-term course of illness in a representative sample of FEP patients. Out of 301 included patients, 266 could be divided into four groups based on substance use patterns during the first two years of treatment: persistent users, episodic users, stop-users and non-users. Results: Patients who stopped using substances within the first two years after diagnosis had outcomes similar to those who had never used with less symptoms than episodic or persistent users.
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