The etiology of these syndromes warrants examination, particularly from a genetic perspective. Nicotine withdrawal is heritable (113) with a proportion of these genes being distinct from those influencing other aspects of smoking. While there have been no formal tests of the univariate heritability of cannabis withdrawal, one study indicates that variance in withdrawal may be adequately captured by a factor representing general vulnerability to cannabis abuse/dependence (114). There are no studies, however, of the extent to which shared genetic influences impact tobacco and cannabis withdrawal, either the syndrome in general or individual features.
