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Depression and Gender Differences 297from diffuse recruitment of cortical regions by children performing cognitive tasksinvolving executive functions to more focal recruitment of PFC regions specificallyimplicated in cognitive control by adolescents (Brown et al., 2005; Caseyet al., 2005a; Durston et al., 2005). Specifically, we hypothesize that four cognitivecompetencies (attentional executive functions, working memory, hypotheticalthinking, and future orientation) attained during adolescence and linked to maturationof the PFC are cognitive developmental “prerequisites” for the CognitiveVulnerability × Stress interaction to “pack its depressogenic punch.” Ironically,adolescents’ increased brain maturation and cognitive competence may come witha cost. It puts them at greater risk for depression than they were in childhood.Earlier, we showed how attention is a self-regulatory mechanism in the causalchain of the cognitive vulnerability-stress model. Cognitively vulnerable individualsbecome stuck in the self-regulatory cycle with their attention focused on negativecognitive content (i.e., rumination; Abramson et al., 2002; MacCoon et al.,2006). An implication is that a cognitively vulnerable individual must haveachieved substantial attentional executive functions in order for the CognitiveVulnerability × Stress interaction to lead to full-blown depression. A cognitivelyvulnerable child who has not developed sufficient competence in selective andsustained attention may generate negative inferences when faced with a negativeevent but will not remain focused on such inferences and, thus, will not be as likelyto suffer their depressogenic effects. We suggest that normative cognitive developmentof self-regulatory executive functions (i.e., sustained and selective attentionand executive control over attentional switching) is a prerequisite for adolescentsto fully engage in attempts to self-regulate negative affect and, thus, for full-blownrumination to occur (Abramson et al., 2002; Steinberg et al., 2004). Attentionalprocesses are known to become more efficient with age and continue to developthrough adolescence (Casey, Trainor, Giedd et al.et al., 1997a). Adolescent developmentalmaturation of the medial PFC and anterior cingulate cortex (ACC)is centrally involved in improved selective attention performance (Botvinik et al.,2001; Casey, Trainor, Giedd et al., 1997a). Thus, as attentional executive controldevelops during adolescence, rumination and the Cognitive Vulnerability × Stressinteraction can fully “pack their punch” in contributing to the onset of and emergenceof gender differences in depression.Similarly, normative development of working memory is essential for maintaininginformation and the present context in mind (Cohen & Servan-Schreiber,1992; Kimberg & Farah, 1993) and, thus, is also an important cognitive capacityunderlying self-regulation. Thus, increases in working memory skills should alsobe a prerequisite for adolescents to fully engage in self-regulation and full-blownrumination. Working memory is most reliably associated with activation of thedorsolateral PFC (Owen, 2000).With the advent of formal operations in adolescence comes the ability to thinkabout possibilities rather than only concrete realities—in other words, abstract,