For CD, the differences in prevalence rates due to the requirement of impairment seem to suggest that there may be a number of individuals who show enough symptoms of the disorder to meet the diagnostic threshold but for whom these symptoms do not cause significant impairment. Thus, studies requiring impairment report lower prevalence rates. In addition, a significant difference between DSM-III-R and DSM-IV was precisely in the addition of a criterion B in CD that required that the disturbance in behavior cause clinically significant impairment in social, academic or occupational functioning. Such criterion was not part of DSM-III-R. Also, differences in prevalence rates based on variability in the diagnostic criteria are likely due to several changes in the criteria for CD that increased the prevalence in studies using the DSM-IV criteria [3], as opposed to the DSM-III-R [2]. Specifically, the DSM-III-R required the three symptoms of CD to be present within the past six months, whereas the DSM-IV increased the window to the past year. Further, the DSM-IV criteria added two symptoms (i.e., often bullies, threatens, or intimidates others; often
