The relationship of neuropsychological impairment to conduct disorder in adolescence: A conceptual review

This review is an attempt to expand the understanding of the neuropsychological mechanisms that may influence the expression of violent or aggressive behavior in adolescents. Although a relative large literature of adult studies examining the relation of neuropsychological impairment and aggression exists, the research literature investigating this relationship in adolescents is much smaller. With a few exceptions, the delinquent literature suffers from methodological problems, including biased sampling methods, small numbers of subjects, failing to objectively diagnose conduct disorder, incorrect use of specific statistical procedures, and lacking of appropriate control groups. In general, a mixed pattern of neuropsychological deficits are displayed across studies, depending on the sampling method, methodological design, statistics employed, control groups, and assessment tools that were utilized. Verbal deficits have been frequently displayed across the literature, while evidence for executive dysfunction varies, depending on the specific construct being evaluated (e.g., attention, cognitive flexibility, concept formation, planning abilities) and the specific population. Relatively inconsistent findings have been observed for visuospatial, sensory, and motor deficits. This article provides a critical review of this literature and discusses the varying impact that any neurological insult will have, depending on premorbid personality and cognitive functioning, location of the lesion, age at which the injury occurred, child's pre- and postinjury environment, and ability of the brain to adapt to acquired deficits as the result of the insult. On the basis of this review and neuropsychological theory, four subgroups within this population are proposed (i.e., adolescents with subcortical injuries, dominant hemisphere temporal-parietal injuries, nondominant hemisphere temporal-parietal injuries, and injuries to the prefrontal regions), which may better explain the neuropsychological and behavioral outcomes exhibited by this heterogeneous population. Recommendations for future research are offered.