Limitations of the present study warrant comment. First, the cross-sectional design of this study does not permit causal inferences regarding the directionality of the ob served associations. Future prospective work using longitudinal data may be a useful next step for work directed at isolating onset and developmental patterns between marijuana use and panic psychopathology. Similarly, research could usefully build on such work by attempting to explicate the patterning between age of onset for marijuana use and panic psychopathology. Second, whereas these results are generalizable to the adult U.S. population, it is not clear whether they are applicable cross-nationally. In light of the global health implications of panic psychopathology and marijuana use problems (e.g., Vega et al., 2002), future studies examining the cross-national stability of the current findings are, therefore, an important next scientific step Finally, the NCS-R survey does not permit a categorization of marijuana abuse or dependence. Thus, future work may benefit by exploring marijuana–panic psychopathology relations using abuse and dependence diagnostic criteria rather than relying exclusively on “marijuana use.” In related fashion, the use of marijuana use history
