“…This conclusion is based on the extant literature that suggests that the co-occurrence of either conduct disorder or anxiety disorder with ADHD interacts with and alters this diagnostic construct in important ways, including its typical clinical phenomenology, psychological characteristics, psychosocial factors, clinical course and outcome, and treatment response. For example, when ADHD is comorbid with conduct disorder, both the neuropsychological deficits (especially in verbal and memory domains) and the outcomes (in terms of drug use and abuse, driving-related accidents, and additional psychiatric comorbidity) appear to be worse than those associated with either ADHD or conduct disorder status alone (Barkley, Guevremont, Anastopoulos, DuPaul, & Shelton, 1993 ;Barkley et al, 1996 ;Halperin et al, 1990 ;Herrero, Hechtman, & Weiss, 1994 ;Mannuzza, Klein, Bessler, Malloy, & LaPadula, 1993 ;Moffitt, 1990 ;Moffitt & Henry, 1989). Moreover, there is preliminary evidence that stimulant medication may not be as effective in reducing motoric activity in children with the aggressive type of ADHD compared to nonaggressive ADHD (Matier, Halperin, Sharma, Newcorn, & Sathaye, 1992).…”