Background Cannabis use among adolescents with depression is prevalent. Dysfunction of the reward system has been implicated in each condition separately, yet rarely examined together. Here, we investigated resting-state properties of reward networks in an adolescent sample with diverse internalizing psychopathology and cannabis use patterns. Methods Clinicians interviewed adolescents and assessed depression severity dimensionally. Cannabis use was characterized by self-report and toxicology screens. Neuroimaging scans were acquired and processed using the Human Connectome Project pipelines. Participant-level resting state data were parcellated, and Reward Expectancy and Reward Attainment network masks derived from a reward task were applied. Graph theoretical metrics, including Strength Centrality (CStr), Eigenvector Centrality (CEig), and Local Efficiency (ELoc), were estimated within each network. Group-level clinical correlates of network properties were assessed with non-parametric analyses (10,000 permutations), adjusted for age, sex, and family-wise error (FWE) rates (pFWE < 0.05). Results In the full sample (N = 131; 15.3 ± 2.2 years; 65.7% female), depression severity was associated with stronger ELoc of the ventral striatum within the Reward Attainment network. Among those who used cannabis (n = 38), heavier cannabis use was linked to weaker CStr of the anterior cingulate cortex and ELoc of the postcentral somatosensory area within the Reward Expectancy network. Exploratory analyses further suggested cannabis-related dorsolateral prefrontal and cerebellar dysconnectivity across the whole brain, as well as sex- and age-moderated effects. Conclusion Our findings provide preliminary evidence for adolescent cannabis use and depression being differentially associated with resting-state reward network properties. Additional research with larger cohort sizes is needed to corroborate findings.

Objective: Cannabis use is prevalent among youth with depression and may alter the reward neurocircuitry, which also plays a role in depression. Yet, reward function in co-occurring cannabis use and depression remains poorly understood. Here, we sought to examine neural reward processing in an adolescent sample with varying cannabis use and depression severity. Methods: Participants completed diagnostic interviews and self-reported depression symptoms dimensionally. Cannabis use patterns were determined from clinician interviews, self-reports, and urine toxicology screens. Structural and Reward Flanker Task functional MRI data were collected and preprocessed using Human Connectome Project-style pipelines. Using a parcellated, network-based approach, we examined neural responses during reward expectancy (reward vs. non-reward cues) and attainment (reward vs. non-reward feedback) in relation to cannabis use and depression severity, controlling for age, sex, and multiple comparisons. Results: In the full sample of 117 adolescents (age: 15.5 ± 2.3 years, 63.3% female), greater depression severity was linked to blunted caudate activity during reward expectancy and heightened activation of posterior cingulate and entorhinal cortices during reward attainment. Among 34 adolescents who used cannabis, heavier use was associated with greater activation in the left mediodorsal posterior thalamus and habenula during reward expectancy, while depression severity positively correlated with activation across cortico-striatal, default, memory, and visual networks during reward attainment. Cannabis use × depression interaction effects were detected in frontal and entorhinal cortices during reward attainment. Exploratory analyses showed sex differences. Conclusions: Our results reveal divergent neural profiles of cannabis use and depression, as well as their additive associations with altered reward processing in adolescents. ### Competing Interest Statement Dr. Russell Tobe reported receiving grant support from Axial Therapeutics, F. Hoffmann-La Roche; Intra-Cellular Therapies, Janssen Research & Development, and MapLight Therapeutics and attending advisory boards for F. Hoffmann-La Roche outside the submitted work. ### Funding Statement This work was supported by the National Institutes of Health (NIH) under award numbers F30DA056227 (to T.N.B.N.); R01MH120601, R01MH131207, R01DA054885, RM1DA055437, R01MH128878, R01MH126821, and R01DA059527 (to V.G., Principal Investigator). T.N.B.N. was additionally supported by NIH training grants T32GM149364 (Medical Scientist Training Program; PI: Myles H. Akabas) and T32TR004537 (PI: H. Dean Hosgood). E.R.S. was also supported by NIH R01MH126981 and by a Breakthrough Award from the International Obsessive-Compulsive Disorder Foundation (IOCDF), both unrelated to the submitted work. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Institutional Review Boards of the University of Miami Miller School of Medicine, Nathan Kline Institute for Psychiatric Research, Albert Einstein College of Medicine, and Icahn School of Medicine at Mount Sinai gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the corresponding author.

Adolescence represents a critical neurodevelopmental period of high vulnerability to the onset of psychiatric conditions. Altered processing of uncertain reward outcomes likely contributes to this vulnerability, yet remains poorly understood. Addressing this knowledge gap, we sought to use the fMRI Reward Flanker Task, originally developed by our group, to examine neural responses to uncertain rewards and their clinical associations. To fully capture clinical correlates, we recruited adolescents with mood and anxiety symptoms ranging from low to high severity, including healthy controls (HC). Participants were 84 psychotropic-medication-free adolescents (15.3 ± 2.1 years; 62% female; 17 HC); all completed diagnostic and dimensional symptom assessments. Neuroimaging data were preprocessed using Human Connectome Project pipelines. Analyses examined participant-level neural responses to uncertain reward expectancy and attainment, adjusted for age, sex, and multiple comparisons. Across the whole sample, uncertain versus certain cues activated the default network and suppressed the fronto-parietal control network. Neural responses during expectancy to uncertain reward were intermediate between responses to certain reward and non-reward stimuli. Outcome attainment following uncertain cues activated stronger neural responses in reward and salience regions compared to reward cues. Anhedonia severity correlated with default network activation during uncertain outcome attainment. Anxiety severity correlated with blunted striatal responses during uncertain vs. certain non-reward expectancy. Exploratory group comparisons revealed that adolescents with mood and anxiety symptoms versus HC showed blunted striatal responses during uncertain versus non-reward expectancy and hyperactivation in visual and default network areas during attainment following uncertain cues. Together, these findings support the role of uncertain reward processing in adolescent mood and anxiety psychopathology.

Suicide is the second leading cause of death among adolescents and young adults, and understanding neurobiological features that distinguish youth experiencing suicidality remains a critical public health challenge. Converging evidence suggests that pain plays a key role in suicidality. Yet, no studies to date have examined the role of pain neurocircuitry in adolescent suicidality. Here, we present preliminary findings from an ongoing functional magnetic resonance imaging (fMRI) investigation of neural pain responses and their associations with suicidality and depression symptomatology in youth.Adolescents (age 12-21; N=24) with mild-to-severe depression completed diagnostic interviews; depression, anxiety, anhedonia, and suicidality scales; and the fMRI Electric Pain Task. Participants observed cues, received painful or non-painful electric stimuli, and rated subjective pain. Scans used high-spatiotemporal resolution 3T sequences and Human Connectome Project processing methodology. Results were evaluated using FSL FEAT at cluster-corrected p<0.05.Painful stimuli engaged canonical pain circuitry, including somatosensory, insula, and anterior-mid cingulate cortices. During pain ratings, adolescents with current suicidality (n=12) had stronger activation in perigenual cingulate, fusiform, and orbitofrontal cortices. Across participants, suicidality severity correlated with subgenual cingulate, posterior insula, ventral striatal, and lateral orbitofrontal activation. Anxiety negatively correlated with pain rating activation in the bilateral insula, caudate, thalamus, and medial temporal lobe. Consummatory anhedonia correlated with dorsomedial prefrontal activation during pain anticipation, while anticipatory anhedonia negatively correlated with lateral occipital activation during pain experience.Though preliminary, findings indicated distinct phases of neural pain response were associated with adolescent suicidality, particularly in ventral cingulate and dopaminergic circuitry, and with depression symptomatology.

Objective:Youth with depression use cannabis at high rates, and exposure to cannabinoids in adolescence has been shown to deleteriously alter the reward system. However, there has been sparse research on the link between adolescent cannabis use and anhedonia, a core symptom of depression and clinical manifestation of reward dysfunction. Here, in a sample of adolescents presenting predominantly with mood and anxiety symptoms, we investigated the relationships between cannabis use and anticipatory and consummatory aspects of anhedonia. Method:Adolescents underwent psychiatric diagnostic interviews and completed dimensional symptom measures. Cannabis use was quantified using information from clinician interviews, self-reports, and urine toxicology screenings. Bivariate associations between cannabis use and anhedonia subconstructs were determined. To further assess associations adjusting for age and sex, linear regression models were performed. We additionally explored how cannabis use was related to other mood and anxiety symptoms, as well as age and sex effects. Results:Among 153 participants (age: 15.9 ± 2.2 years, 64.1% biologically female), we identified 49 who used cannabis. Primary analyses showed that relative to those who never used or had only tried cannabis once, adolescents who used cannabis endorsed worse anticipatory anhedonia. More frequent cannabis use also correlated with greater anticipatory anhedonia. Exploratory analyses revealed that adolescents diagnosed with cannabis use disorder reported greater depression and anxiety than those with non-disordered cannabis use, and female and male youth differed in their experiences of mood and anxiety symptoms related to cannabis use. Conclusion:Our findings have important public health implications as policies on cannabis evolve. We advocate for the detection and interventions specific to anhedonia for the management of cannabis use in youth with internalizing conditions. Diversity & Inclusion Statement:We worked to ensure sex and gender balance in the recruitment of human participants. We worked to ensure race, ethnic, and/or other types of diversity in the recruitment of human participants. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented sexual and/or gender groups in science. We actively worked to promote sex and gender balance in our author group. We actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our author group. While citing references scientifically relevant for this work, we also actively worked to promote sex and gender balance in our reference list. While citing references scientifically relevant for this work, we also actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our reference list. The author list of this paper includes contributors from the location and/or community where the research was conducted who participated in the data collection, design, analysis, and/or interpretation of the work.We worked to ensure that the study questionnaires were prepared in an inclusive way.

White matter pathways, typically studied with diffusion tensor imaging (DTI), have been implicated in the neurobiology of obsessive-compulsive disorder (OCD). However, due to limited sample sizes and the predominance of single-site studies, the generalizability of OCD classification based on diffusion white matter estimates remains unclear. Here, we tested classification accuracy using the largest OCD DTI dataset to date, involving 1336 adult participants (690 OCD patients and 646 healthy controls) and 317 pediatric participants (175 OCD patients and 142 healthy controls) from 18 international sites within the ENIGMA OCD Working Group. We used an automatic machine learning pipeline (with feature engineering and selection, and model optimization) and examined the cross-site generalizability of the OCD classification models using leave-one-site-out cross-validation. Our models showed low-to-moderate accuracy in classifying (1) “OCD vs. healthy controls” (Adults, receiver operator characteristic-area under the curve = 57.19 ± 3.47 in the replication set; Children, 59.8 ± 7.39), (2) “unmedicated OCD vs. healthy controls” (Adults, 62.67 ± 3.84; Children, 48.51 ± 10.14), and (3) “medicated OCD vs. unmedicated OCD” (Adults, 76.72 ± 3.97; Children, 72.45 ± 8.87). There was significant site variability in model performance (cross-validated ROC AUC ranges 51.6–79.1 in adults; 35.9–63.2 in children). Machine learning interpretation showed that diffusivity measures of the corpus callosum, internal capsule, and posterior thalamic radiation contributed to the classification of OCD from HC. The classification performance appeared greater than the model trained on grey matter morphometry in the prior ENIGMA OCD study (our study includes subsamples from the morphometry study). Taken together, this study points to the meaningful multivariate patterns of white matter features relevant to the neurobiology of OCD, but with low-to-moderate classification accuracy. The OCD classification performance may be constrained by site variability and medication effects on the white matter integrity, indicating room for improvement for future research.

Introduction:Neuroinflammatory processes have been extensively implicated in the underlying neurobiology of numerous neuropsychiatric disorders. Elevated C-reactive protein (CRP), an indicator of non-specific inflammation commonly utilized in clinical practice, has been associated with depression in adults. In adolescents, our group previously found CRP to be associated with altered neural reward function but not with mood and anxiety symptoms assessed cross-sectionally. We hypothesized that the distinct CRP findings in adolescent vs. adult depression may be due to chronicity, with neuroinflammatory effects on psychiatric disorders gradually accumulating over time. Here, we conducted a longitudinal study to evaluate if CRP levels predicted future onset or progression of depression in adolescents.Methods:Participants were 53 adolescents (ages 14.74 ± 1.92, 35 female), 40 with psychiatric symptoms and 13 healthy controls. At baseline, participants completed semi-structured diagnostic evaluations; dimensional assessments for anxiety, depression, anhedonia, and suicidality severity; and bloodwork to quantify CRP levels. Clinical assessments were repeated at longitudinal follow-up after approximately 1.5 years. Spearman's correlation between CRP levels and follow-up symptom severity were controlled for BMI, age, sex, and follow-up interval and considered significant at the two-tailed, Bonferroni-adjusted p < 0.05 level.Results:After correction for multiple comparisons, no relationships were identified between baseline CRP levels and follow-up symptom severity.Conclusion:CRP levels were not significantly associated with future psychiatric symptoms in adolescents in this preliminary analysis. This may suggest that CRP is not a useful biomarker for adolescent depression and anxiety. However, future longitudinal studies with larger sample sizes and incorporating additional indicators of neuroinflammation are needed.

Background: Suicide is the second leading cause of death in adolescents and young adults in the United States. Well-established risk factors for suicide are depression and past suicide attempts. People experiencing suicidality may represent a distinct neurobiological subgroup. Converging evidence has implicated inflammation in depression. Here we sought to investigate relationships between suicidality and immune markers in youth experiencing diverse mood and anxiety symptoms. We hypothesized that adolescents with suicidality would exhibit a unique immune signature. Methods: Adolescents underwent semi-structured interviews and completed self-reported measures to assess psychopathology, including suicidality. Fasting blood samples were collected, cultured with and without lipopolysaccharide (LPS) to stimulate an inflammatory response, and analyzed for 41 immune analytes. To assess how immune function related to suicidality categorically and dimensionally, we conducted group comparisons and correlations while controlling for multiple comparisons using false discovery rate (FDR). To further uncover subtle immune-suicidality relationships, we employed a data-driven approach using factor analysis to extract major immune factors, each of which was subsequently correlated with suicidality measures.Results: Among 126 participants, 29 were healthy controls and 97 participants had psychopathology; within the clinical group, 57 experienced suicidality. Three immune analytes differed between suicidal and non-suicidal adolescents in the LPS condition: Flt-3L (pFDR = 0.0246), GM-CSF (pFDR = 0.0246), and IFN-γ (pFDR = 0.0246). These analytes were negatively correlated with the Beck Scale for Suicide Ideation (BSSI): Flt-3L (ρ = −0.19, p = 0.04); GM-CSF (ρ = −0.26, p = 0.004); IFN-γ (ρ =−0.33, p = 0.0003). GM-CSF also negatively correlated with number of suicide attempts (ρ = −0.39, p = 0.003). Factor analysis revealed further associations between immune factors, derived from full 41-analyte panels, and suicidality across all sample culture conditions. Conclusions: Peripheral immune function may be distinctly altered in adolescent suicidality. Future work should examine immune-suicidality relationships longitudinally.

Studies in adults have linked stress-related activation of the immune system to the manifestation of psychiatric conditions. Using a translational design, this study aimed to examine the impact of social stress on immune activity in adolescents and on neuronal activity in a preclinical mouse model. Participants were 31 adolescents (ages 12–19), including 25 with mood and anxiety symptoms. Whole-blood samples were collected before and after the Trier Social Stress Test (TSST), a stress-inducing public speaking task, then cultured for 6 hours in the presence and absence of the inflammatory endotoxin lipopolysaccharide (LPS). Effects of TSST and LPS on 41 immune biomarkers were examined using repeated-measures analysis of variance. Separately, juvenile (8-week-old) male mice were non-stressed or exposed to reminder social defeat then intraperitoneally injected with saline or LPS (n = 6/group). Brains were perfused and collected for immunohistochemistry and confocal microscopy at 0, 1, 6, and 24 hours post-injection. The activity was determined by the density of cFos-positive neurons in the paraventricular hypothalamus, paraventricular thalamus, and basolateral amygdala, regions known to show sustained activation to immunological challenge. Analyses in the adolescent study indicated a strong effect of LPS but no effects of TSST or TSST×LPS interaction on immune biomarkers. Similarly, reminder social defeat did not induce sustained neuronal activity changes comparable to LPS immunological challenge in juvenile mice. Our convergent findings across species suggest that the acute immune response to stress documented in adults is not present in youth. Thus, aging and chronicity effects may play an important role in the inflammatory response to acute psychosocial stress.

Anhedonia is a salient transdiagnostic psychiatric symptom associated with increased illness severity and chronicity. Anhedonia is also present to varying degrees in non-clinical cohorts. Here, we sought to examine factors influencing expression of anhedonia. Participants (N = 335) were recruited through the Nathan Kline Institute-Rockland Sample, an initiative to deeply phenotype a large community sample across the lifespan. Utilizing a data-driven approach, we evaluated associations between anhedonia severity, indexed by Snaith-Hamilton Pleasure Scale (SHAPS), and 20 physical, developmental, and clinical measures, including Structured Clinical Interview for DSM-IV, Beck Depression Inventory, State-Trait Anxiety Inventory, NEO Five-Factor Inventory-3 (NEO-FFI-3), BMI, Hemoglobin A1C, and demography. Using a bootstrapped AIC-based backward selection algorithm, seven variables were retained in the final model: NEO-FFI-3 agreeableness, extraversion, and openness to experience; BMI; sex; ethnicity; and race. Though median SHAPS scores were greater in participants with psychiatric diagnoses (18.5) than those without (17.0) (U = 12238.5, z = 2.473, p = 0.013), diagnosis and symptom measures were not retained as significant predictors in the final robust linear model. Participants scoring higher on agreeableness, extraversion, and openness to experience reported significantly lower anhedonia. These results demonstrate personality as a mild-to-moderate but significant driver of differences in experiencing pleasure in a community sample.

Evidence suggests that adolescent cannabis use results in long-lasting reward circuit alterations and heightened risk for future depression. Here, we examined whether reward network topology differs among adolescents with and without a history of cannabis use, independent of depression severity. Our ongoing research program focuses on adolescent depression, recruiting and evaluating youth from the New York City metropolitan area through clinician-based interviews and self-reported symptom measures. For this analysis, we included data from 71 participants (ages: 15.15 ± 2.05 years; 66% female) across a range of depressive severity as indexed by the Beck Depression Inventory (BDI). History of cannabis use was determined from interview reports and urine tests. fMRI was performed on a 3T Siemens Skyra. Preprocessing followed the Human Connectome Project (HCP) Pipelines. Resting-state data were parcellated via the Cole-Anticevic Brain-wide Network Partition, then subdivided into 3 reward networks based on a reward fMRI task. Weighted graph-theoretical metrics (Strength Centrality–CStr, Eigenvector Centrality–CEig, Local Efficiency–ELoc) were estimated within each network. Nonparametric group comparisons accounted for sex and familywise error rate (FWE). Adolescent cannabis users showed stronger Reward Prediction Error network CStr in the right cerebellum (pFWE < .05), which trended toward significance when adjusted for depression (pFWE = .0519). At a relaxed threshold (puncorrected < .005), cannabis use implicated Reward Prediction Error CStr in the left fusiform face complex and Reward Attainment CStr in the left nucleus accumbens and right dorsolateral prefrontal cortex, controlling for depression. No association was detected between cannabis use and Reward Anticipation CStr, or for CEig or ELoc in any network. Our results indicate differential resting-state network properties across reward nodes in adolescent cannabis users spanning a spectrum of depression symptomatology. These findings further implicate cannabis use in reward circuitry alterations among depressed youth. As our study is ongoing, future analyses will include data from additional participants.

Suicide is the third leading cause of death in adolescents and adults up to age 34 in the United States. A well-established risk factor for suicide is an active episode of depression and a history of a suicide attempt, suggesting that depressed individuals with prior suicide attempts may represent a distinct neurobiological subgroup. Large evidence has implicated immune system activation in depression across age groups. Here we sought to extend that work to suicidal behavior among depressed youth. We hypothesized that adolescents with depression and a history of suicidal behavior would exhibit a unique immune signature. Participants were 126 adolescents including 29 healthy controls and 96 participants with a mood disorder; within the mood disorder cohort, 39 were nonsuicidal and 58 were suicidal. All had semistructured interviews and self-report measures such as the Beck Depression Inventory (BDI) and Temporal Experience of Pleasure Scale (TEPS). Blood samples collected at 8am after overnight fasting were analyzed for 41 cytokines using multiplex. Cytokines were summarized for the analysis groups and compared between the 3 groups using Kruskal-Wallis test. Factor analysis was applied to the cytokines data to extract the factors explaining most of the variance. Spearman correlation was used to assess associations between each of the chosen factors and dimensional measures of depression, anhedonia, and suicidality. Platelet-derived growth factor (PDGF-AB-BB) and monocyte chemotactic protein (MCP-3) significantly differed between healthy controls and suicidal participants (p = .0100; p = .0097) but not between nonsuicidal participants and controls (p = .4846; p = .1139). Factor analysis revealed that factor 4, which PDGF-AB-BB was heavily loaded onto, was correlated with the BDI (correlation = 0.19, p = .045), the TEPS-A (correlation = -0.28, p = .005), and TEPS-C (correlation = -0.23, p = .02). These results suggest preliminary support for a distinct cytokine profile of suicidal participants when compared to healthy controls. The correlation between factor 4 and the BDI and TEPS demonstrates a potential relationship between depression, anhedonia, and cytokines such as PDGF-AA-BB.

Abstract White matter pathways, typically studied with diffusion tensor imaging (DTI), have been implicated in the neurobiology of obsessive-compulsive disorder (OCD). However, due to limited sample sizes and the predominance of single-site studies, the generalizability of OCD classification based on diffusion white matter estimates remains unclear. Here, we tested classification accuracy using the largest OCD DTI dataset to date, involving 1,336 adult participants (690 OCD patients and 646 healthy controls) and 317 pediatric participants (175 OCD patients and 142 healthy controls) from 18 international sites within the ENIGMA OCD Working Group. We used an automatic machine learning pipeline (with feature engineering and selection, and model optimization) and examined the cross-site generalizability of the OCD classification models using leave-one-site-out cross-validation. Our models showed low-to-moderate accuracy in classifying (1) “OCD vs. healthy controls'' (Adults, receiver operator characteristic-area under the curve = 57.19 ± 3.47 in the replication set; Children, 59.8 ± 7.39), (2) “unmedicated OCD vs. healthy controls” (Adults, 62.67 ± 3.84; Children, 48.51 ± 10.14), and (3) “medicated OCD vs. unmedicated OCD” (Adults, 76.72 ± 3.97; Children, 72.45 ± 8.87). There was significant site variability in model performance (cross-validated ROC AUC ranges 51.6–79.1 in adults; 35.9–63.2 in children). Machine learning interpretation showed that diffusivity measures of the corpus callosum, internal capsule, and posterior thalamic radiation contributed to the classification of OCD from HC. The classification performance appeared greater than the model trained on grey matter morphometry in the prior ENIGMA OCD study (our study includes subsamples from the morphometry study). Taken together, this study points to the meaningful multivariate patterns of white matter features relevant to the neurobiology of OCD, but with low-to-moderate classification accuracy. The OCD classification performance may be constrained by site variability and medication effects on the white matter integrity, indicating room for improvement for future research.