Methodological flaws and inconsistencies confound interpretation of today's literature. Based on this synthesis of available evidence and our clinical experience, we propose recommendations for further discussion.

Recent years have seen considerable progress in epidemiological and molecular genetic research into environmental and genetic factors in schizophrenia, but methodological uncertainties remain with regard to validating environmental exposures, and the population risk conferred by individual molecular genetic variants is small. There are now also a limited number of studies that have investigated molecular genetic candidate gene-environment interactions (G × E), however, so far, thorough replication of findings is rare and G × E research still faces several conceptual and methodological challenges. In this article, we aim to review these recent developments and illustrate how integrated, large-scale investigations may overcome contemporary challenges in G × E research, drawing on the example of a large, international, multi-center study into the identification and translational application of G × E in schizophrenia. While such investigations are now well underway, new challenges emerge for G × E research from late-breaking evidence that genetic variation and environmental exposures are, to a significant degree, shared across a range of psychiatric disorders, with potential overlap in phenotype.

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Background: Prenatal nicotine exposure is associated with increased neonatal mortality, low birth weight, and smaller head circumference. Opioid-dependent pregnant women show a particularly high prevalence of tobacco smoking and are at greater risk for additional adverse events. However, little is known about the impact of tobacco smoking on opioid-maintained pregnant women and neonatal outcomes. Patients and Methods: This study examined the effect of cigarette smoking on 139 opioid-maintained pregnant women and their neonates. Forty-five percent of the participants were maintained on slow-release oral morphine (SROM), 39% received methadone maintenance, and 16% received buprenorphine. Participants were divided into two groups: (1) women who reported a low cigarette consumption of ≤10 cigarettes/day (56.8%) and (2) those reporting heavy consumption of ≥20 cigarettes/day (43.2%). Neonatal outcome measures were assessed, and a standardized Finnegan score was applied to determine the neonatal abstinence syndrome (NAS). Results: Fifty-two percent of the newborns did not require treatment for NAS (54% of neonates born to methadone-maintained mothers, 30% born to SROM-maintained mothers, and 95% born to buprenorphine-maintained mothers; p < 0.001). Heavy cigarette consumption was associated with significantly lower neonatal birth weight (p < 0.001), smaller birth length (p = 0.017) as well as with the severity of NAS (p = 0.03). With regard to concomitant consumption of opioids (p = 0.54), cocaine (p = 0.25), amphetamines (p = 0.90) or benzodiazepines (p = 0.09), no significant differences between heavy or low nicotine consumption were noted. Conclusion: Heavy tobacco smoking in opioid-maintained pregnant women is associated with adverse medical and developmental consequences for the newborn. Future treatment programs for this target group should focus on an individualized approach to opioid maintenance therapy in addition to offering specially tailored counseling for smoking cessation.

Results support high rates of smoking with little change during pregnancy among opioid-dependent patients, regardless of the type of agonist medication received. These findings are consistent with evidence that suggests nicotine effects, and interactions may be similar for buprenorphine compared with methadone. The outcomes further highlight that aggressive efforts are needed to reduce/eliminate smoking in opioid-dependent pregnant women.