interventions might include psychosocial programs to directly strengthen family and child protective factors or reduce risk factors; programs in social settings that affect child development, such as preschools, schools, and social welfare agencies; or policy-level changes, such as funding prevention services or directly increasing a family’s access to resources.

Risk and Protective Factors Tend to Be Correlated and to Have Cumulative Effects

Risk factors tend to be positively correlated with each other and negatively correlated with protective factors. Thus, some young people have multiple risk factors, and those with multiple risk factors are less likely to have protective factors. For example, in a five-state sample of 6th through 12th graders, those who were in the highest quintile on a cumulative measure of risk factors were likely to be in the lowest quintile on the measure of protective factors (Pollard, Hawkins, and Arthur, 1999).

Furthermore, the presence of multiple risk or protective factors tends to strengthen the prediction of disorder or positive development (Rutter, 1979; Sameroff, Gutman, and Peck, 2003; Goodyer and Altham, 1991; Fergussson and Horwood, 2003). The effect of cumulative risk and protective factors is also found in studies of populations exposed to a common risk factor, such as poverty, parental substance abuse, parental mental illness, or parental divorce (Wyman, 2003; Roosa, Sandler, et al., 1988; Sandler, Wolchik, et al., 1986). In one analysis, for example, although no single risk factor had a strong relation to disorder or positive development, the accumulation of risk factors across family, parent, peers, and community had a substantial effect in predicting multiple problem outcomes (Sameroff, Gutman, and Peck, 2003). When compared with those with eight or more risk factors, youth with three or fewer risk factors had significantly better odds of showing psychological adjustment and self-competence and not showing problem behavior.

One implication of cumulative risk and protection is that preventive interventions may be more effective when they target multiple risk and protective factors rather than just one. In some cases, mediational analysis from an experimental trial can identify which risk and protective factors are responsible for program effects (e.g., Tein, Sandler, et al., 2006). In other cases, when multiple risk and protective factors are targeted, the trial can be designed specifically to test whether components intended to change specific risk and protective factors have additive effects to improve preventive impact (West and Aiken, 1997).

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