Individual differences in threat and reward neural circuitry activation: Testing dimensional models of early adversity, anxiety and depression

Genetic variation in endocannabinoid signaling: Anxiety, depression, and threat- and reward-related brain functioning during the transition into adolescence

BACKGROUND

The endocannabinoid system modulates neural activity throughout the lifespan. In adults, neuroimaging studies link a common genetic variant in fatty acid amide hydrolase (FAAH C385A)-an enzyme that regulates endocannabinoid signaling-to reduced risk of anxiety and depression, and altered threat- and reward-related neural activity. However, limited research has investigated these associations during the transition into adolescence, a period of substantial neurodevelopment and increased psychopathology risk.

METHODS

This study included FAAH genotype and longitudinal neuroimaging and neurobehavioral data from 4811 youth (46% female; 9-11 years at Baseline, 11-13 years at Year 2) from the Adolescent Brain Cognitive DevelopmentSM Study. Linear mixed models examined the effects of FAAH and the FAAH x time interaction on anxiety and depressive symptoms, amygdala reactivity to threatening faces, and nucleus accumbens (NAcc) response to happy faces during the emotional n-back task.

RESULTS

A significant main effect of FAAH on depressive symptoms was observed, such that depressive symptoms were lower across both timepoints in those with the AA genotype compared to both AC and CC genotypes (p's<0.05). There were no significant FAAH x time interactions for anxiety, depression, or neural responses (p's>0.05). Additionally, there were no main effects of FAAH on anxiety or neural responses (p's>0.05).

CONCLUSIONS

Our findings add to emerging evidence linking the FAAH C385A variant to lower risk of psychopathology, and extend these findings to a developmental sample. In particular, we found lower depressive symptoms in FAAH AA genotypes compared to AC and CC genotypes. Future research is needed to characterize the role of the FAAH variant and the eCB system more broadly in neurodevelopment and psychiatric risk.

The neurobiological effects of childhood maltreatment on brain structure, function, and attachment

Childhood maltreatment is a risk factor for psychopathologies, and influences brain development at specific periods, particularly during early childhood and adolescence. This narrative review addresses phenotypic alterations in sensory systems associated with specific types of childhood maltreatment exposure, periods of vulnerability to the neurobiological effects of maltreatment, and the relationships between childhood maltreatment and brain structure, function, connectivity, and network architecture; psychopathology; and resilience. It also addresses neurobiological alterations associated with maternal communication and attachment disturbances, and uses laboratory-based measures during infancy and case-control studies to elucidate neurobiological alterations in reactive attachment disorders in children with maltreatment histories. Moreover, we review studies on the acute effects of oxytocin on reactive attachment disorder and maltreatment and methylation of oxytocin regulatory genes. Epigenetic changes may play a critical role in initiating or producing the atypical structural and functional brain alterations associated with childhood maltreatment. However, these changes could be reversed through psychological and pharmacological interventions, and by anticipating or preventing the emergence of brain alterations and subsequent psychopathological risks.

Childhood Maltreatment and Amygdala Response to Interpersonal Threat in a Transdiagnostic Adult Sample: The Role of Trait Dissociation

BACKGROUND

Childhood maltreatment (CM) confers risk for different mental disorders as well as transdiagnostic symptoms such as dissociation. Aberrant amygdala response to interpersonal threat may link CM to transdiagnostic psychopathology and has recently been shown to depend on type and developmental timing of CM experiences. Still, most studies on CM and threat-related amygdala response employ categorical disorder-specific perspectives and fail to consider type and timing of CM exposure. We aimed to investigate associations between CM, amygdala response to interpersonal threat, and dimensional psychopathological symptoms including trait dissociation in a transdiagnostic adult sample, specifically considering type, timing, and duration of CM.

METHODS

We conducted a cross-sectional neuroimaging study in 141 participants with varying levels of CM, including mostly female participants with major depressive disorder (n = 36), posttraumatic stress disorder (n = 34), and somatic symptom disorder (n = 35) and healthy volunteers (n = 36). Participants underwent functional magnetic resonance imaging during an emotional face-matching task, completed the brief German interview version of the Maltreatment and Abuse Chronology of Exposure scale, and answered self-report measures of transdiagnostic CM-related symptoms including trait dissociation. Data were analyzed using a machine learning-based model comparison procedure.

RESULTS

In our transdiagnostic sample, neither type nor timing or duration of CM predicted amygdala response to interpersonal threat. Instead, trait dissociation predicted blunted bilateral amygdala response and emerged as a possible mediator between CM and amygdala function.

CONCLUSIONS

Trait dissociation may be an important confounder in the widely documented association between CM and threat-related amygdala response, which should be considered in future longitudinal studies.

Association between reward-related functional connectivity and tri-level mood and anxiety symptoms

Depression and anxiety are associated with abnormalities in brain regions that process rewards including the medial orbitofrontal cortex (mOFC), the ventral striatum (VS), and the amygdala. However, there are inconsistencies in these findings. This may be due to past reliance on categorical diagnoses that, while valuable, provide less precision than may be required to understand subtle neural changes associated with symptoms of depression and anxiety. In contrast, the tri-level model defines symptom dimensions that are common (General Distress) or relatively specific (Anhedonia-Apprehension, Fears) to depression and anxiety related disorders, which provide increased precision. In the current study, eligibility was assessed by quasi-orthogonal screening questionnaires measuring reward and threat sensitivity (Behavioral Activation Scale; Eysenck Personality Questionnaire-Neuroticism). These participants were assessed on tri-level symptom severity and completed the Monetary Incentive Delay task during fMRI scanning. VS-mOFC and VS-amygdala connectivity were estimated during reward anticipation and reward outcome. Heightened General Distress was associated with lower VS-mOFC connectivity during reward anticipation (b = -0.064, p = 0.021) and reward outcome (b = -0.102, p = 0.014). Heightened Anhedonia-Apprehension was associated with greater VS-amygdala connectivity during reward anticipation (b = 0.065, p = 0.004). The present work has important implications for understanding the coupling between the mOFC and vS and the amygdala and the vS during reward processing in the pathophysiology of mood and anxiety symptoms and for developing targeted behavioral, pharmacological, and neuromodulatory interventions to help manage these symptoms.