The interplay of childhood maltreatment and maternal depression in relation to the reward positivity in youth

Guided by developmental psychopathology and dual-risk frameworks, the present study examined the interplay between childhood maltreatment and maternal major depression history in relation to neural reward responsiveness in youth. The sample consisted of 96 youth (ages 9–16; M = 12.29 years, SD = 2.20; 68.8% female) drawn from a large metropolitan city. Youth were recruited based on whether their mothers had a history of major depressive disorder (MDD) and were categorized into two groups: youth with mothers with a history of MDD (high risk; HR; n = 56) and youth with mothers with no history of psychiatric disorders (low risk; LR; n = 40). The reward positivity (RewP), an event-related potential component, was utilized to measure reward responsiveness and the Childhood Trauma Questionnaire measured childhood maltreatment. We found a significant two-way interaction between childhood maltreatment and risk group in relation to RewP. Simple slope analysis revealed that in the HR group, greater childhood maltreatment was significantly associated with reduced RewP. The relationship between childhood maltreatment and RewP was not significant among the LR youth. The present findings demonstrate that the association between childhood maltreatment and blunted reward responsiveness is dependent on whether offspring have mothers with histories of MDD.

Acute Ketamine Modulated Functional Brain Coupling and Dissociative and Affective States in Human Subjects: Interim Analyses

Ketamine is a non-competitive antagonist of the N-methyl-D-aspartate (NMDA) glutamate receptor that is both a drug of abuse and an FDA-approved anesthetic used off-label for treatment-resistant depression. Despite its growing clinical use for depression and pain, the relationships between the acute dissociative and affective effects of ketamine that contribute to its abuse liability and therapeutic potential, along with the neural mechanisms underlying these effects, are not well established. To address this need, we have implemented a randomized, double-blinded, placebo-controlled, within-subjects mechanistic trial. Healthy adult subjects undergo infusion with two fixed doses of subanesthetic racemic intravenous (IV) ketamine and placebo and their acute responses are assessed with self-report questionnaires, behavioral measures, hormone levels, and neuroimaging. As planned in our analysis strategy, we present interim results for the first 7 subjects of our study, focusing on dissociative and affective states and resting functional brain coupling signatures of these states. The first key finding was that ketamine induced dose-dependent increases in dissociation and related intoxication. Ketamine also altered affective states, reducing emotional insensitivity but increasing stress assessed by cortisol. Second, ketamine had an effect on altering brain connectivity, particularly for specific connections between regions of the reward and negative affect circuits and involving thalamic sub-regions. Third, regarding brain-response associations, ketamine-induced increases in amygdala-anteroventral thalamus coupling were correlated with greater dissociation and intoxication, whereas decreases in the coupling of the anteromedial thalamus and posterior parietal thalamus were correlated with increased sensory aspects of reward responsiveness. Additional specific correlations were observed between affective measures relevant to reward responsiveness or its absence and drug-altered changes in localized functional connections involving the nucleus accumbens (NAcc), amygdala, and thalamic sub-regions. We also discovered a consistent profile of negative associations between ketamine altered connectivity involving the NAcc and specific thalamic sub-regions and effects of anxiety. Further, drug-altered increases in the coupling of the amygdala and anteroventral thalamus were associated with increases in cortisol, an indicator of biochemical stress. The findings highlight the utility of integrating self-reports, objective measures, and functional neuroimaging to disentangle the brain states underlying specific acute responses induced by ketamine. With the likely continued expansion of FDA indications for ketamine, understanding acute responses and underlying neural mechanisms is important for maximizing the therapeutic potential of ketamine while minimizing the risk of promoting misuse or abuse of this substance. Clinical Trial Registration ID #: NCT03475277

Genetic and depressive traits moderate the reward-enhancing effects of acute nicotine in young light smokers

Rates of light smoking have increased in recent years and are associated with adverse health outcomes. Reducing light smoking is a challenge because it is unclear why some but not others, progress to heavier smoking. Nicotine has profound effects on brain reward systems and individual differences in nicotine’s reward-enhancing effects may drive variability in smoking trajectories. Therefore, we examined whether a genetic risk factor and personality traits known to moderate reward processing, also moderate the reward-enhancing effects of nicotine. Light smokers (n=116) performed a Probabilistic Reward Task to assess reward responsiveness after receiving either nicotine or placebo (order counterbalanced). Individuals were classified as nicotine dependence ‘risk’ allele carriers (rs16969968 A-allele carriers) or non-carriers (non-A-allele carriers), and self-reported negative affective traits were also measured. Across the whole sample, reward responsiveness was greater following nicotine compared to placebo (p=0.045). For Caucasian A-allele carriers but not non-A-allele carriers, nicotine enhanced reward responsiveness compared to placebo for those who received the placebo first (p=0.010). Furthermore, for A-allele carriers but not non-A-allele carriers who received nicotine first, the enhanced reward responsiveness in the nicotine condition carried over to the placebo condition (p<0.001). Depressive traits also moderated the reward-enhancing effects of nicotine (p=0.010) and were associated with more blunted reward responsiveness following placebo but enhanced reward responsiveness following nicotine. These findings suggest that individual differences in a genetic risk factor and depressive traits alter nicotine’s effect on reward responsiveness in light smokers and may be important factors underpinning variability in smoking trajectories in this growing population.

Measuring Behavioral Inhibition and Behavioral Activation in Older Adults: Construct Validity of the Dutch BIS/BAS Scales

Research on the validity of the behavioral inhibition system/behavioral approach system (BIS/BAS) scales focused on adolescent, student and adult populations. This study is the first to examine the psychometric properties of the BIS/BAS scales in a community ( n = 368) and a clinical sample ( n = 160) of older adults. Exploratory structural equation modelling with target rotation to the Carver and White model supported the construct validity of the BIS/BAS scales. Internal consistencies of the scales were generally satisfactory. Female participants scored higher on BIS and BAS-Reward Responsiveness compared with males. The community-dwelling sample scored higher on BAS-Drive and BAS-Reward Responsiveness compared with the clinical sample. Concerning the nomological net, BIS was positively related to Anxiety, Depression, maladaptive coping strategies, Neuroticism and Cluster C personality disorders. BAS was positively related to Openness, Extraversion, Active Confronting and Cluster B personality disorders and negatively related to the schizoid personality disorder. The BIS/BAS Scales are a useful instrument for measuring Gray’s theory of personality in older adults.