<p>Nicotine consumption during the prodromal phase of schizophrenia – a review of the literature</p>

Abstract

Recent research has fueled a debate concerning the role of nicotine in the emergence of schizophrenia. The three main hypotheses are: (a) the self-medication effect, (b) the causal relationship hypothesis, or (c) the shared diathesis hypothesis. To explore this role, the study of nicotine consumption during the initial prodromal phase of schizophrenia offers important opportunities. In the present work, 10 relevant studies are reviewed, out of 727 retrieved citations, in order to address questions regarding the prevalence of smoking in the prodromal period, the time of smoking initiation, existing patterns of tobacco use in relation with the escalation of prodromal symptoms into first psychotic episode, and potential differences in symptomatology between smokers and nonsmokers. Even though there was considerable heterogeneity among studies, relevant findings are discussed. Prevalence of nicotine use during the prodromal period was reported to be 16.6–46%. Tobacco use was found to be taken up most often before or during the prodromal period of schizophrenia. Even though a protective role of smoking has been reported by one study, other studies report an increased risk for psychosis, with hazard ratios 2.77 (95% CI: 2.34–3.43) and 2.21 (95% CI: 1.11–4.42) for female and male heavy smokers (11–20 and >20 cigarettes/day), respectively. In a different study, the risk of onset was associated with the progressive use of cannabis and tobacco prior to onset, particularly with rapid escalation to the highest levels of use. Also, nicotine use in ultra high risk (UHR) for developing psychosis subjects is associated with elevated cognitive performance, namely better processing speed, visual learning, and spatial working memory. As a conclusion, it appears that evidence accumulates supporting a possible etiologic role of smoking, in the emergence of schizophrenia along with diverse effects on patients’ symptomatology, already demonstrable at the prodromal phase. Future research employing better-defined criteria should further explore the patterns of use and effects of nicotine during the schizophrenia prodrome.

Clustering of physical health multimorbidity in 68,392 people with severe mental illness and matched comparators: a lifetime prevalence analysis of United Kingdom primary care data

“…However, with both SMI and chronic physical health conditions, a prodromal stage or period of undiagnosed disease may occur and therefore diagnosis dates may not give a clear indication of temporal association. Furthermore, previous studies have found increased physical health problems prior to schizophrenia(57, 58) and bipolar disorder diagnoses(59) and that health risk factors for physical health conditions such as smoking(60) and alcohol and drug misuse may be present prior to SMI diagnosis(61).…”

Does nicotine exposure during adolescence modify the course of schizophrenia-like symptoms? Behavioral analysis in a phencyclidine-induced mice model

“…The association between tobacco smoking and SCHZ has gained attention in recent years [ 108 ]. However, scant studies in prodrome patients and in animal models of SCHZ investigated this comorbidity during adolescence, which has the potential to identify mechanisms of nicotine interference in the development of SCHZ.…”

Adolescent Substance Use and the Brain: Behavioral, Cognitive and Neuroimaging Correlates

“…Heavy nicotine dependence is prevalent in 16–46% of those in the prodromal phase of schizophrenia (Gogos et al, 2019 ), leading researchers to question if there is a causal relationship between schizophrenia and smoking (i.e., does smoking increase the risk for schizophrenia, or does having schizophrenia promote smoking habits to alleviate disease symptoms? ), if the risk for smoking and schizophrenia share common mechanistic underpinnings, or both (Khokhar et al, 2018 ).…”