Fewer but heavier caffeine consumers in schizophrenia: a case-control study.
ABSTRACT According to the literature, there is an association between schizophrenia and caffeine consumption, but it is not clear whether schizophrenia is associated with either higher prevalence of daily caffeine intake or the amount consumed. In this study we compared our previously published schizophrenia patients (n=250) with a control sample (n=290) after controlling for demographic variables and tobacco and alcohol consumption. Current caffeine intake was less frequent in schizophrenia patients (59%, 147/250) than in controls (70%, 204/290). In the multivariate analyses, caffeine intake was less frequent at an older age and in schizophrenia patients, and more frequent in smokers and alcohol users. Among caffeine consumers, heavy caffeine intake (> or =200 mg/day) was significantly associated with schizophrenia (64%, 94/147 in schizophrenia versus 36%, 73/204 in controls), as well as older age and smoking. Daily amount of caffeine intake and smoked cigarettes correlated significantly in the schizophrenia group but not in the control group; the correlation of caffeine intake with nicotine dependence was low and non-significant in both groups. The association between current smoking and heavy caffeine intake may be partly explained by a pharmacokinetic effect: tobacco smoke compounds induce caffeine metabolism by the cytochrome P450 1A2. Although schizophrenia by itself may be associated with heavy caffeine intake in caffeine users, part of this association was explained by the association between schizophrenia and smoking. The relationship between caffeine and alcohol intake appeared to be more complex; alcohol and caffeine use were significantly associated, but within caffeine users alcohol was associated with less frequent heavy caffeine consumption among smokers. In future studies, the measurement of plasma caffeine levels will help both to better define heavy caffeine intake and to control for smoking pharmacokinetic effects.
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ABSTRACT: The aim of the present study was to explore and compare the caffeine intake, intoxication, withdrawal and dependence prevalence in Italian psychiatric patients and healthy subjects. Three hundred and sixty-nine out- and inpatients, suffering from different psychiatric disorders, and 104 healthy subjects were included in the study. They were assessed by the SCID and by a structured interview for caffeine intoxication and withdrawal and for substance dependence applied to caffeine use. Patients and healthy subjects did not differ in terms of current caffeine intake (mg/day, mean+/-SD: 281+/-325 vs. 288+/-148, respectively), while the maximum lifetime intake of caffeine was significantly higher in the first group (mg/day, mean SD: 630+/-549 vs. 504+/-344, respectively; F=4.897, p=.03) where it was significantly related to the CGI severity item scores (rho=.107; p=.04). In both patients and healthy subjects, a lower age was related to a higher current caffeine intake, while both current and maximum lifetime caffeine intake in the healthy subjects were significantly higher in men than in women. The patients suffering from eating disorders reported higher current caffeine intake than those with anxiety or mood disorders. The prevalence of dependence and intoxication was significantly higher in the patients than in the healthy subjects, without inter-group differences. Healthy subjects showed a trend towards a higher prevalence of withdrawal. Our study highlights the need that a more accurate attention should be paid to the caffeine use which seems to be strongly, although generically, related to different psychiatric disorders.European Psychiatry 07/2009; 25(4):230-5. · 2.77 Impact Factor