and problem gambling. For example, Breslau and Davis (1992) identified several unique risk factors for chronic compared with nonchronic PTSD.
Etiological research must also consider how the effects of age and being in a cohort (a group of people born in the same year or decade) increase or decrease one's risk for initiating gambling or developing a gambling problem. Although these effects are infrequently considered in existing pathological and problem gambling research, Erikson's stages of development (Erickson, 1963, 1968, 1982) are one explanatory model that accounts for aging effects and could potentially be applied when investigating gambling behaviors. Specifically, the model hypothesizes that, as people age, they move through several developmental stages that correspond to certain stage-related tasks. When applied to gambling behavior, the implication is that, at certain developmental stages, the motivation for and expectations about gambling might change. A recent review demonstrated that gambling among young people occurs on a developmental continuum of gambling involvement ranging from no gambling experimentation to gambling with serious consequences (Stinchfield and Winters, 1998). These effects pertain to how risk factors and outcomes change with age and differ among groups of people (Mok and Hraba, 1991).
Cohort effects pertain to specific events that affect groups of people born during the same time period (Mok and Hraba, 1991). When applied to gambling behavior, this means that increases in gambling opportunities during a certain period in history may affect a certain age group of people. For example, a cohort of same-age people who are passing through the age of risk for gambling problems when gambling opportunities are expanding may experience greater and increasing exposure to, involvement in, and social acceptance of gambling during their lifetimes than a cohort of same-age people at risk during periods of fewer gambling opportunities. In addition, circumstances can affect more than one cohort in the same way or in different ways. A classic example of an event that changed the trajectory of same-age