Resilience to substance use disorder following childhood maltreatment: association with peripheral biomarkers of endocannabinoid function and neural indices of emotion regulation

Alterations of the endocannabinoid system in adolescents with non-suicidal self-injury as a function of childhood maltreatment

Non-suicidal self-injury (NSSI) is a highly prevalent phenomenon in adolescence, often associated with prior traumatic experiences. The development and maintenance of NSSI is associated with dysregulation of the stress response, and evidence suggests that the hypothalamic-pituitary-adrenal (HPA) axis plays an important role. The endocannabinoid system is a neuromodulatory system in close functional interaction with the HPA axis. Several studies have reported alterations of the endocannabinoid system in adult patients with post-traumatic stress disorder. However, the role of the endocannabinoid system in children and adolescents with NSSI is less clear, and previously no study examined endocannabinoids in youth with experiences of maltreatment. N-arachidonyl ethanolamide (AEA) and 2-arachidonyl glycerol (2-AG) were quantified alongside sociodemographic and clinical characteristics in n = 148 adolescents (12-17 years of age). Analyses addressed group differences comparing healthy controls (HC, n = 38), patients with NSSI without (NSSI - CMT, n = 42) and with a history of childhood maltreatment (NSSI + CMT, n = 68). We show that AEA is reduced in adolescents with NSSI independent of childhood maltreatment. Further, we present first evidence for a negative association between AEA and NSSI frequency as well as AEA and the severity of childhood maltreatment. This is the first study providing evidence for alterations in the endocannabinoid system in children and adolescents engaging in repetitive NSSI. Findings from the study support current endocannabinoid-hypotheses on the neurobiology of trauma and adversity, extending existing findings of altered endocannabinoid signaling following exposure to traumatic events to a well-powered sample of children and adolescents.

The consequences of childhood maltreatment on dual-diagnosis psychiatric conditions and clinical outcomes in substance use disorders: A systematic review and meta-analysis

BACKGROUND

Evidence suggests that the phenotypic expression of substance use disorders (SUD) may be influenced by exposure to childhood maltreatment (CM).

OBJECTIVE

To assess how CM could impact severity (relapse, treatment dropout, withdrawal), age of substance use onset, psychiatric dual diagnosis (depression, anxiety, PTSD, distress), and self-harm behavior/suicide attempts in adults with SUD, we performed a systematic review and meta-analyses.

METHODS

We searched PubMed, Web of Science, PsycINFO, and Embase to identify articles examining the association of maltreatment (physical, sexual, or emotional abuse or neglect) before age 18 years with clinical features and course of illness SUD. Multilevel random effects models were performed. Heterogeneity was quantified using the I2 statistic. Subgroup/meta-regression analyses were employed to investigate sources of heterogeneity. Risk of bias was assessed using an adapted version of the Newcastle-Ottawa Quality Assessment Scale.

RESULTS

Forty-five studies were included. CM was associated with all tested outcomes, such as anxiety (OR = 1.52; 95 % CI = 1.39, 1.65), depression (OR = 1.57; 95 % CI = 1.40, 1.77), PTSD (OR = 1.67; 95 % CI = 1.40, 1.99), psychological distress (OR = 1.49; 95 % CI = 1.24, 1.78), self-harm behavior and suicidal attempts (OR = 1.70; 95 % CI = 1.47, 1.96), SUD severity (OR = 1.15; 95 % CI = 1.04, 1.26), and younger age of onset use (OR = 0.76; 95 % CI = 0.69, 0.84). However, comparisons between outcomes revealed that the association was stronger for dual diagnosis symptoms/conditions than for measures of SUD severity itself. Meta-analyses for some outcomes had large statistical heterogeneity, though these were partly addressed through additional analyses. Gender, mean age of participants, polysubstance use pattern, substance of preference, and CM subtype were found to be moderators of these associations.

CONCLUSIONS

The consequences of CM on individuals with SUD are more closely linked to co-occurring psychiatric manifestations than to the severity of common clinical indicators (relapse, treatment dropout, withdrawal), and this finding has important implications.

FUNDING

None.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (CRD42021245936).

Endocannabinoid concentrations in major depression: effects of childhood maltreatment and relation to hippocampal volume

Evidence from preclinical animal models suggests that the stress-buffering function of the endocannabinoid (eCB) system may help protect against stress-related reductions in hippocampal volume, as is documented in major depressive disorder (MDD). However, stress exposure may also lead to dysregulation of this system. Thus, pathways from marked stress histories, such as childhood maltreatment (CM), to smaller hippocampal volumes and MDD in humans may depend on dysregulated versus intact eCB functioning. We examined whether the relation between MDD and peripheral eCB concentrations would vary as a function of CM history. Further, we examined whether eCBs moderate the relation of CM/MDD and hippocampal volume. Ninety-one adults with MDD and 62 healthy comparison participants (HCs) were recruited for a study from the Canadian Biomarker Integration Network in Depression program (CAN-BIND-04). The eCBs, anandamide (AEA) and 2-arachidonylglycerol (2-AG), were assessed from blood plasma. Severe CM history was assessed retrospectively via contextual interview. MDD was associated with eCBs, though not all associations were moderated by CM or in the direction expected. Specifically, MDD was associated with higher AEA compared to HCs regardless of CM history, a difference that could be attributed to psychotropic medications. MDD was also associated with higher 2-AG, but only for participants with CM. Consistent with hypotheses, we found lower left hippocampal volume in participants with versus without CM, but only for those with lower AEA, and not moderate or high AEA. Our study presents the first evidence in humans implicating eCBs in stress-related mechanisms involving reduced hippocampal volume in MDD.

Endocannabinoids and Stress-Related Neurospsychiatric Disorders: A Systematic Review and Meta-Analysis of Basal Concentrations and Response to Acute Psychosocial Stress

Background: Dysregulation of the endocannabinoid (eCB) system is implicated in various stress-related neuropsychiatric disorders (SRDs), including anxiety, depression, and post-traumatic stress disorder (PTSD). In this systematic review and meta-analysis, our objectives were to characterize circulating anandamide (AEA) and 2-arachidonoylglycerol (2-AG) concentrations at rest and in response to acute laboratory-based psychosocial stress in individuals with SRDs and without (controls). Our primary aims were to assess the effects of acute psychosocial stress on eCB concentrations in controls (Aim 1), compare baseline (prestress) eCB concentrations between individuals with SRDs and controls (Aim 2), and explore differential eCB responses to acute psychosocial stress in individuals with SRDs compared with controls (Aim 3). Methods: On June 8, 2023, a comprehensive review of the MEDLINE (PubMed) database was conducted to identify original articles meeting inclusion criteria. A total of 1072, 1341, and 400 articles were screened for inclusion in Aims 1, 2, and 3, respectively. Results: Aim 1, comprised of seven studies in controls, revealed that most studies reported stress-related increases in AEA (86%, with 43% reporting statistical significance) and 2-AG (83%, though none were statistically significant except for one study in saliva). However, meta-analyses did not support these patterns (p's>0.05). Aim 2, with 20 studies, revealed that most studies reported higher baseline concentrations of both AEA (63%, with 16% reporting statistical significance) and 2-AG (60%, with 10% reporting statistical significance) in individuals with SRDs compared with controls. Meta-analyses confirmed these findings (p's<0.05). Aim 3, which included three studies, had only one study that reported statistically different stress-related changes in 2-AG (but not AEA) between individuals with PTSD (decrease) and controls (increase), which was supported by the meta-analysis (p<0.001). Meta-analyses showed heterogeneity across studies and aims (I2=14-97%). Conclusion: Despite substantial heterogeneity in study characteristics, samples, and methodologies, consistent patterns emerged, including elevated baseline AEA and 2-AG in individuals with SRDs compared with controls, as well as smaller stress-related increases in 2-AG in individuals with SRDs compared with controls. To consider eCBs as reliable biomarkers and potential intervention targets for SRDs, standardized research approaches are needed to clarify the complex relationships between eCBs, SRDs, and psychosocial stress.

Early life stress is associated with greater negative emotionality and peripheral inflammation in alcohol use disorder

Early life stress (ELS) increases risk for psychiatric illness, including alcohol use disorder (AUD). Researchers have hypothesized that individuals with and without a history of ELS who have the same primary DSM-5 diagnosis are clinically and biologically distinct. While there is strong support for this hypothesis in the context of mood disorders, the hypothesis remains largely untested in the context of AUD. This study investigated the impact of ELS on the neuroclinical phenomenology and inflammatory profile of individuals with AUD. Treatment-seeking adults with AUD (N = 163) completed the Adverse Childhood Experiences (ACE) Questionnaire and phenotypic battery as part of a pharmacotherapy trial for AUD (NCT03594435). Participants were classified as having "no-ELS," (ACE = 0) "moderate-ELS," (ACE = 1, 2 or 3) or "high-ELS" (ACE = 4 + ). The Addictions Neuroclinical Assessment domains incentive salience and negative emotionality were derived and used to assess the neuroclinical phenomenology of AUD. We tested (1) cumulative ELS as a predictor of ANA domains and (2) ELS group differences in ANA domains. A subset of participants (N = 98) provided blood samples for a biomarker of peripheral inflammation (C-reactive protein; CRP); analyses were repeated with CRP as the outcome variable. Greater ELS predicted higher negative emotionality and elevated CRP, but not incentive salience. The high-ELS group exhibited greater negative emotionality compared with the no-ELS and moderate-ELS groups, with no difference between the latter two groups. The high-ELS group exhibited elevated CRP compared with the no/moderate-ELS group. Findings suggest that high-ELS exposure is associated with a unique AUD neuroclinical presentation marked by greater negative emotionality, and inflammatory profile characterized by elevated peripheral CRP.

PREFRONTAL CORRELATES OF FEAR GENERALIZATION DURING ENDOCANNABINOID DEPLETION

Maladaptive fear generalization is one of the hallmarks of trauma-related disorders. The endocannabinoid 2-arachidonoylglycerol (2-AG) is crucial for modulating anxiety, fear, and stress adaptation but its role in balancing fear discrimination versus generalization is not known. To address this, we used a combination of plasma endocannabinoid measurement and neuroimaging from a childhood maltreatment exposed and non-exposed mixed population combined with human and rodent fear conditioning models. Here we show that 2-AG levels are inversely associated with fear generalization at the behavioral level in both mice and humans. In mice, 2-AG depletion increases the proportion of neurons, and the similarity between neuronal representations, of threat-predictive and neutral stimuli within prelimbic prefrontal cortex ensembles. In humans, increased dorsolateral prefrontal cortical-amygdala resting state connectivity is inversely correlated with fear generalization. These data provide convergent cross-species evidence that 2-AG is a key regulator of fear generalization and suggest 2-AG deficiency could represent a trauma-related disorder susceptibility endophenotype.

Child maltreatment and resilience in adulthood: a protocol for a systematic review and meta-analysis

Background: Although child maltreatment (CM) has been linked to health problems and poor psychosocial functioning, not all individuals exposed to CM develop or experience negative consequences later in life. This suggests that some individuals show resilience after being exposed to CM. However, conclusions have been limited by inconsistent findings across different CM subtypes and resilience domains.Objective: To develop a protocol for conducting a systematic review and meta-analysis to quantify associations between CM (overall and its subtypes) and resilience (global and its multiple domains) in adulthood, and to examine moderators and mediators of these associations.Method: PubMed, PsycINFO, Embase, Scopus, and Web of Science will be searched to identify relevant studies on the association between CM (exposure) and resilience (outcome) in adults (≥ 18 years). Data will be screened and extracted by at least two independent reviewers. The methodological quality of the included studies will be independently assessed with a modified version of the Newcastle-Ottawa Scale (NOS). If deemed viable, a meta-analysis will be conducted using a random effects model. Heterogeneity of evidence will be estimated with the I2 statistic, and publication bias will be assessed. The effects of potential moderators (e.g. timing and severity of CM, age, sex, family cohesion, socio-economic status, country/region) will be analysed using meta-regression and subgroup analyses, and meta-analytical structural equation modelling will be employed to synthesise indirect mediation effects. Candidate moderators and mediators (e.g. genetic factors, brain functioning, attachment style, personality traits, physical activity, and social support) will be also examined qualitatively.Conclusions: This protocol will facilitate a systematic review and meta-analysis that has the potential to enhance our knowledge about the association between CM exposure in early life and resilience in adulthood. Understanding associations and underlying mechanisms between CM and resilience is potentially important in informing prevention and interventions to sustain health and improve outcomes among adults with a history of CM.PROSPERO registration: CRD42023394120.