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«by Amy Lynn Byrd, Ph.D. B.S. in Psychology, College of Charleston, 2006 M.S. in Clinical Psychology, University of Pittsburgh, 2010 Submitted to the ...»

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Incorporating aspects of both reward and punishment systems, Newman and colleagues (Newman, 1998; Patterson & Newman, 1993; Wallace & Newman, 2008) proposed that CP can be attributed to deficits in the modulation of both systems, specifically when the avoidance of punishment requires overriding a dominant reward response. Drawing upon these theories, considerable behavioral work has evaluated the extent to which CP youth manifest abnormalities in reward and/or punishment processing. In addition, researchers have attempted to examine the degree to which potential abnormalities may be specific to a subset of youth, characterized by high levels of CU traits or psychopathic features. This works is review below, following a review of important developmental considerations.

2.3.1 Developmental Considerations Research in this area has focused primarily on adolescents with CP and it is important to highlight several relevant development considerations prior to a review of the literature. First, there may be substantial developmental change in the manifestation of CP over time, specifically

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1998). Adolescence marks a transition period noted for drastic physical, psychological, and social development. Most pertinent to our interpretation of the current literature are marked behavioral increases in risk-taking and reward seeking behaviors that are thought to reflect still developing neurobiological systems (Steinberg & Morris, 2001). Along these lines, it is important to note the substantial change in the neural circuitry subserving reward and punishment processing in youth, seen most prominently during adolescence. Specifically, there is a significant increase in axonal myelination coupled with decreases in both cortical and subcortical gray matter as well as with functional changes in reward/punishment neural circuitries (e.g., Giedd, 2004). Some studies have documented a heightened sensitivity to reward in the striatum when comparing adolescents to adults (Ernst, et al., 2005; Galvan, et al., 2006) and this, coupled with underdeveloped regulatory frontal regions, has been hypothesized to lead to increases in problem behaviors during adolescence (Fareri, Martin, & Delgado, 2008; Luna, et al., 2001). Indeed, the prevalence of delinquent behaviors tends to rise and peak in adolescence, followed by dissipation for most individuals into adulthood (Farrington, 1986). As such, attempts to characterize reward/punishment mechanisms that give rise to early-onset, chronic CP may be most effective during pre-adolescence, prior to heightened neural maturation and associated increases in CP related behaviors. Thus, the following review of the literature seeks to highlight gaps in the current literature related to this issue, emphasizing the importance of developmental timing with regard to interpretation.

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Extensive behavioral work has attempted to disentangle the contributions of reward and punishment processing in CP youth using a variety of behavioral paradigms. Results from past empirical research are summarized below within the context of each of the proposed mechanisms underlying severe and persistent CP: 1) primary abnormality in reward processing; 2) primary abnormality in punishment processing; or 3) abnormalities in both reward and punishment processing. In addition, efforts to evaluate the extent to which these abnormalities may be most pronounced in a subgroup of CP youth with 1) CU traits or 2) psychopathic features are highlighted. Lastly, distinctions between samples of youth in late childhood versus adolescence are noted as this is particularly important with regard to interpretation and design of the current dissertation.

2.4.1 Primary Abnormality in Reward Processing Research attempting to examine whether aberrant reward processing characterizes CP youth has utilized a variety of paradigms, the majority of which assess ‘risk taking’ or responsivity to immediate rewards despite potential punishment. These tasks included the Iowa Gambling Task (IGT; Bechara, Damasio, Damasio, & Anderson, 1994), the Risky Choice Task (RCT; Rogers, et al., 2003) and the Balloon Analogue Risk Task (BART; Lejuez, et al., 2002). Studies utilizing these tasks have fairly consistently shown youth with CP to exhibit a greater affinity for large, immediate rewards despite a high probability of punishment relative to controls (Fairchild, et al., 2009; Miura, 2009; Schutter, van Bokhoven, Vanderschuren, Lochman, & Matthys, 2011) and

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differences in risk taking behavior were seen within groups of CP when subtypes were based on the severity of CP (e.g., violent vs. non-violent; Miura, 2009) or age of onset (Fairchild, et al., 2009). However, research assessing samples of CP youth with increased psychopathic features, were linked to higher levels of risk taking (Blair, Colledge, & Mitchell, 2001; Fairchild, et al., 2009), suggesting these abnormalities may be most pronounced in this subgroup of youth.

Interestingly, those studies examining CU traits specifically found no significant differences in overall risk taking (Centifanti & Modecki, 2013; Marini & Stickle, 2010), suggesting that reward sensitivity and heightened risk taking may be less associated with the core affective features of psychopathy.

Taken together, findings may seem to provide initial evidence for abnormalities in reward processing among youth with CP, particularly those with psychopathic features. However, it is important to consider these findings within the context of several limitations. First, while these tasks aim to assess reward processing, the incorporation of both reward and punishment preclude firm notions about the mechanism underlying the reward dominant response style as abnormalities in reward and/or punishment processing may be responsible for these effects. It is also noteworthy that null findings in this area are specific to tasks that more successfully isolated responsivity to reward by reinforcing the majority of responses and in some instances excluding punishment (Castellanos-Ryan, Rubia, & Conrod, 2011; MacPherson, et al., 2010; Marini & Stickle, 2010; Newman & Kosson, 1986), negating theories that propose a primary dysfunction in reward processing. Second, and perhaps more importantly, all of the aforementioned studies utilized samples of adolescents, with the majority of positive studies failing to include adequate control groups. Moreover, the only study to examine reward processing in late childhood found

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al., 2010). Thus, given discrepancies based on developmental timing of assessment and lack of control groups, it is possible that performance deficits reflect more normative increases in risktaking and reward-seeking behaviors during adolescence.

These findings, while notably limited, fail to provide support for a primary dysfunction in reward processing and instead suggest that deficits in behavioral performance may be most evident in the presence of competing reward and punishment cues. However, as underscored above, behavioral attempts to isolate and examine reward processing in youth with CP are limited and highlight the need for alternative empirical methods (e.g., neuroimaging) that may be more effective in evaluating abnormalities in reward processing in youth with CP. Moreover, there is a dearth of research examining reward processing as a mechanism underlying CP in childhood, necessitating the need for continued investigation within this domain.

2.4.2 Primary Abnormality in Punishment Processing Empirical work investigating a primary deficit in punishment processing has mostly utilized psychophysiological measures to examine reflexive responses to punishment, with the majority of studies focusing on individual differences in responsivity to inherently aversive stimuli (e.g., loud tones). Research in the area demonstrates consistent results across both late childhood and adolescence, with CP youth, relative to controls, demonstrating reduced responsivity to randomly presented aversive tones (Fairchild, van Goozen, Stollery, & Goodyer, 2008; Herpertz, et al., 2001; van Goozen, Snoek, Matthys, van Rossum, & van Engeland, 2004) and to cues of impending punishment (Fairchild, et al., 2008; Loeber, Pardini, Stouthamer-Loeber, & Raine, 2007; Raine & Venables, 1981; Raine, Venables, & Williams, 1996). This suggests that youth

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their ability to form associations with cues of impending punishment. At the same time, there is some evidence to suggest that CP youth can cognitively identify cue-punishment pairing in a post-task questionnaire (Fairchild, et al., 2008), indicating that they may be aware of these contingencies but exhibit deficits in the affective component of processing.

Further, despite long standing theory that punishment insensitivity is characteristic of individuals with psychopathic features, the only study that attempted to examine this empirically found no differences in responsivity to punishment among delinquent youth with high vs. low psychopathic features (Fung, et al., 2005). Given the consistent findings described above, one may conclude that these deficits are not specific to this subgroup of CP youth and are instead associated with CP more generally. At the same time, it is important to note that research in this area is limited and Fung et al. (2005) failed to differentiate between variants of psychopathy as indexed by CU traits. Thus, further investigation is warranted.

Finally, the majority of work in this area has focused on reactivity to inherently aversive stimuli, with much less research examining abnormalities in responsivity to other forms of punishment (e.g., loss of money). Those studies that have examined the extent to which youth with CP demonstrate reduced sensitivity to loss of money have produced inconsistent results (Beauchaine, Katkin, Strassberg, & Snarr, 2001; Matthys, van Goozen, Snoek, & van Engeland, 2004). It is particularly important to better understand potential differences in processing alternative punishments as they are inherent to everyday experiences and are often used as integral components of parenting interventions.

As a whole, studies in this area provide strong evidence for reduced sensitivity to inherently aversive stimuli (e.g., loud tones), which is suggestive of a primary deficit in

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examining responsivity to alternative forms of punishment, such as monetary loss, as well as research investigating whether aberrant punishment processing is specific to CP youth with heightened CU traits.

2.4.3 Abnormalities in Reward and Punishment Processing The majority of empirical work examining reward/punishment processing in youth with CP has implemented tasks that incorporate aspects of both reward and punishment processing. Two of the most commonly used paradigms (i.e., passive-avoidance learning, response-reversal) require participants to learn by trial-and-error and vary in the predictability and probability of received reward (e.g., fixed versus variable). In both instances, youth are required to adapt their performance based on the receipt of reward and punishment. Results consistently find CP youth to show performance deficits in the face of competing reward and punishment relative to controls, suggesting difficulties inhibiting a dominant response to reward despite increasing punishment (e.g., Fonseca & Yule, 1995; Matthys, et al., 2004; O'Brien & Frick, 1996; O'Brien, Frick, & Lyman, 1994). These findings have been replicated in community, clinical, and offender samples of youth in late childhood (Daughtery & Quay, 1991; Fonseca & Yule, 1995;

Matthys, et al., 2004; Matthys, van Goozen, De Vries, Cohen-Kettenis, & Van Engeland, 1998;

O'Brien & Frick, 1996; O'Brien, et al., 1994) and adolescence (Budhani & Blair, 2005; Fisher & Blair, 1998; Fonseca & Yule, 1995; Frick, et al., 2003; Shapiro, Quay, Hogan, & Schwartz, 1988). In addition, CP youth with psychopathic features showed pronounced deficits on these tasks relative to CP youth without psychopathic features, with some evidence that CU traits in particular may differentiate a subgroup of CP youth with severe performance deficits (Budhani

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that CP youth, particularly those with CU traits/psychopathic features have difficulty inhibiting a prepotent reward response in the face of increasing punishment, specifically when the avoidance of punishment requires overriding a dominant reward response.

In light of the consistent deficits on tasks that examine punishment sensitivity, it may be that abnormalities in punishment processing are driving performance differences on these tasks.

However, it is also possible that youth with CP evidence greater difficulties when cognitive demands are high and they are required to shift attention to less salient cues of punishment in the face of a dominant reward focused action. This is consistent with Newman’s response modulation hypothesis (e.g., Patterson & Newman, 1993), which posits deficits in the modulation of both reward and punishment processing systems. However, at present the mechanism underlying these performance deficits remains unclear and the extent to which this is attributable to abnormalities in reward processing, punishment processing or a combination of the two warrants further investigation.

2.4.4 Limitations Taken as a whole, it appears that youth with CP exhibit abnormalities in reward and punishment processing, with some suggestion that deficits may be most pronounced in CP youth with CU traits or psychopathic features. However, while the behavioral literature has increased our understanding of associations between reward/punishment processing and CP, there are several limitations. First, these studies are limited in their inability to completely disentangle the mechanisms underlying reward and punishment processing. For example, while behavioral tasks may identify a reward dominant response style, it is difficult to determine whether a hyperactive

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behavioral paradigms discussed above incorporate aspects of reward and punishment, making it difficult to discern potential differences in the strength of associations with CP. Moreover, behavioral studies and the theory they are founded upon often fail to acknowledge the complexities of reward and punishment processing, as each of these mechanisms are comprised of multiple phases of learning (Ernst, Pine, & Hardin, 2006; Seymour, Singer, & Dolan, 2007).



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