Motivational and hedonic impairments are core aspects of a variety of types of psychopathology. These impairments cut across diagnostic categories and may be critical to understanding major aspects of the functional impairments accompanying psychopathology. Given the centrality of motivational and hedonic systems to psychopathology, the Research Domain Criteria (RDoC) initiative includes a "positive valence" systems domain that outlines a number of constructs that may be key to understanding the nature and mechanisms of motivational and hedonic impairments in psychopathology. These component constructs include initial responsiveness to reward, reward anticipation or expectancy, incentive or reinforcement learning, effort valuation, and action selection. Here, we review behavioral and neuroimaging studies providing evidence for impairments in these constructs in individuals with psychosis versus in individuals with depressive pathology. There are important differences in the nature of reward-related and hedonic deficits associated with psychosis versus depression that have major implications for our understanding of etiology and treatment development. In particular, the literature strongly suggests the presence of impairments in in-the-moment hedonics or "liking" in individuals with depressive pathology, particularly among those who experience anhedonia. Such deficits may propagate forward and contribute to impairments in other constructs that are dependent on hedonic responses, such as anticipation, learning, effort, and action selection. Such hedonic impairments could reflect alterations in dopamine and/or opioid signaling in the striatum related to depression or specifically to anhedonia in depressed populations. In contrast, the literature points to relatively intact in-the-moment hedonic processing in psychosis, but provides much evidence for impairments in other components involved in translating reward to action selection. Particularly, individuals with schizophrenia exhibit altered reward prediction and associated striatal and prefrontal activation, impaired reward learning, and impaired reward-modulated action selection.
Objective Adult major depressive disorder (MDD) is associated with reduced cortico-limbic functional connectivity thought to indicate decreased top-down control of emotion. However, it is unclear whether such connectivity alterations are also present in early childhood onset MDD. Method Fifty-one children ages 7–11 years, prospectively studied since preschool age, completed resting state fMRI and were assigned to four groups: 1) C-MDD (N=13) personal history of early childhood onset MDD; 2) M-MDD (N=11) a maternal history of affective disorders; 3) CM-MDD (N=13) both maternal and early childhood onset MDD or 4) CON (N=14) without either a personal or maternal history. We used seed-based resting state functional connectivity (rsfcMRI) analysis in an independent sample of adults to identify networks showing both positive (e.g., limbic regions) and negative (e.g., dorsal frontal/parietal regions) connectivity with the amygdala. These regions were then used in ROI based analyses of our child sample. Results We found a significant interaction between maternal affective disorder history and the child's MDD history for both positive and negative rsfcMRI networks. Specifically, when copared to CON, we found reduced connectivity between the amygdala and the “Negative Network” in children with C-MDD, M-MDD and CM-MDD. Children with either C-MDD or a maternal history of MDD (but not CM-MDD) displayed reduced connectivity between the amygdala and the “Positive Network”. Conclusions Our finding of an attenuated relationship between the amygdala, a region affected in MDD and involved in emotion processing, and cognitive control regions is consistent with a hypothesis of altered regulation of emotional processing in C-MDD suggesting developmental continuity of this alteration into early childhood.
Striatal response to reward has been of great interest in the typical development and psychopathology literatures. These parallel lines of inquiry demonstrate that while typically developing adolescents show robust striatal response to reward, adolescents with major depressive disorder (MDD) or those at high-risk for MDD show blunted response to reward. Understanding how these findings intersect is critical for the development and application of early preventative interventions in at-risk children, ideally before the sharp increase in the rate of MDD onset that occurs in adolescence. Robust findings relating blunted striatal response to reward and MDD-risk are reviewed and situated within a normative developmental context. We highlight the need for future studies investigating longitudinal development, specificity to MDD, and roles of potential moderators and mediators.
Carver and White's Behavioral Inhibition System/Behavioral Activation System (BIS/BAS) Scale has been a useful tool for studying individual differences in reward/punishment sensitivity; however, its factor structure and invariance across development have not been well tested. In the current study, we examined the factor structure of the BIS/BAS Scale across five age groups: 6-10-year-old children (N=229), 11-13-year-old early adolescents (N=311), 14-16-year-old late adolescents (N=353), 18-22-year-old young adults (N=844), and 30-45-year-old adults (N=471). Given poor fit of the standard four-factor model (BIS, Reward Responsivity, Drive, Fun Seeking) in the literature, we conducted exploratory factor analyses in half of the participants and identified problematic items across age groups. The four-factor model showed poor fit in our sample whereas removing the BAS Fun Seeking subscale and problematic items from the remaining subscales improved fit in confirmatory factor analyses conducted with the second half of the participants. The revised model showed strict invariance across age groups and by sex, indicating consistent factor structure, item loadings, thresholds, and unique/residual variances. Additionally, in our cross-sectional data, we observed non-linear relations between age and subscale scores, where scores tended to be higher in young adulthood than childhood and later adulthood. Furthermore, sex differences emerged across development; adolescent and adult females had higher BIS scores than males in this age range, whereas sex differences were not observed in childhood. These differences may help us to understand the rise in internalizing psychopathology in adolescence, particularly in females. Future developmental studies are warranted to examine the impact of rewording problematic items.
Advances in cognitive and affective neuroscience come largely from within-subjects comparisons, in which the functional significance of neural activity is determined by contrasting two or more experimental conditions. Clinical and social neuroscience studies have attempted to leverage between-subject variability in such condition differences to better understand psychopathology and other individual differences. Shifting from within-to between-subjects comparisons requires that measures have adequate internal consistency to function as individual difference variables. This is particularly relevant for difference scores-which have lower reliability. The field has assumed reasonable internal consistency of neural measures based on consistent findings across studies (i.e., if a within-subject difference in neural activity is robust, then it must be reliable). Using one of the most common fMRI paradigms in the clinical neuroscience literature (i.e., a face- and shape-matching task), in a large sample of adolescents (N = 139) we replicate a robust finding: amygdala activation is greater for faces than shapes. Moreover, we demonstrate that the internal consistency of the amygdala in face and shape blocks was excellent (Spearman-Brown corrected reliability [SB] > .94). However, the internal consistency of the activation difference between faces and shapes was nearly zero (SB = -.06). This reflected the fact that the amygdala response to faces and shapes was highly correlated (r = .97) across individuals. Increased neural activation to faces versus shapes could not possibly function as an individual difference measure in these data-illustrating how neural activation can be robust within subjects, but unreliable as an individual difference measure. Strong and reproducible condition differences in neural activity are not necessarily well-suited for individual differences research-and neuroimaging studies should always report the internal consistency of, and correlations between, activations used in individual differences research.
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