Misconceptions about gene-environment interactions in psychiatry

Long-term mortality of persons with severe mental illness and diabetes: a population-based cohort study in Denmark

“…Persons suffering from both severe mental illness and diabetes tended to have higher mortality than would be expected when adding the independent risk of death associated with each of the two diseases, but a lower mortality than would be expected if the risks were multiplied. Not all authors agree upon using the synergy index as an indication of biological interaction (Greenland, 1993;Zammit et al 2010), as it rests upon the assumption that there is no residual confounding from unmeasured or unknown risk factors (Greenland, 1993). Thus the results regarding synergistic action should be interpreted cautiously.…”

Association Between Cannabis and Psychosis: Epidemiologic Evidence

“…see 37,38). More recently an interaction has been reported (39), and replicated in one study, between cannabis use and AKT1 on psychosis risk (40); however there are substantial concerns around gene environment interaction studies (38,41), and currently evidence that effects of cannabis differ according to variation at AKT1 is not robust.…”

Gene × Environment Interaction Models in Psychiatric Genetics

“…Several researchers have criticized this optimistic view, pointing out that theG×E interaction effects identified to date aresmall, with odds ratios generally between 0.67 and 1.5 [24], limiting the potential influence of G×E interaction on advances in psychiatric genetics and clinical practice [25, 26, 15]. In particular, the power for finding main effects might only marginally increase by including G×E interaction effects in the statistical model [18] [27].…”

“…In addition, G×E findings might help identify the underlying biological pathway only through the detection of qualitative G×E interactions, a case known to be rare in epidemiology [16]. Thus, there is an ongoing debate about the benefit of G×E interaction research and the considerable amounts of resources spent in the field [14, 23, 26]. …”