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Alzheimer’s dementia (AD) is a progressive, neurodegenerative disease often accompanied by neuropsychiatric symptoms that profoundly impact both patients and caregivers. Agitation is among the most prevalent and distressing of these symptoms and often requires treatment. Appropriate therapeutic interventions depend on understanding the biological basis of agitation and how it may be affected by treatment. This narrative review discusses a proposed pathophysiology of agitation in Alzheimer’s dementia based on convergent evidence across research approaches. Available data indicate that agitation in Alzheimer’s dementia is associated with an imbalance of activity between key prefrontal and subcortical brain regions. The monoamine neurotransmitter systems serve as key modulators of activity within these brain regions and circuits and are rendered abnormal in AD. Patients with AD who exhibited agitation symptoms during life have alterations in neurotransmitter nuclei and related systems when the brain is examined at autopsy. The authors present a model of agitation in Alzheimer’s dementia in which noradrenergic hyperactivity along with serotonergic deficits and dysregulated striatal dopamine release contribute to agitated and aggressive behaviors.
Amygdala and dorsal anterior cingulate cortex responses to facial emotions have shown promise in predicting treatment response in medication-free major depressive disorder (MDD). Here, we examined their role in the pathophysiology of clinical outcomes in more chronic, difficult-to-treat forms of MDD.
Methods
Forty-five people with current MDD who had not responded to ⩾2 serotonergic antidepressants (n = 42, meeting pre-defined fMRI minimum quality thresholds) were enrolled and followed up over four months of standard primary care. Prior to medication review, subliminal facial emotion fMRI was used to extract blood-oxygen level-dependent effects for sad v. happy faces from two pre-registered a priori defined regions: bilateral amygdala and dorsal/pregenual anterior cingulate cortex. Clinical outcome was the percentage change on the self-reported Quick Inventory of Depressive Symptomatology (16-item).
Results
We corroborated our pre-registered hypothesis (NCT04342299) that lower bilateral amygdala activation for sad v. happy faces predicted favorable clinical outcomes (rs[38] = 0.40, p = 0.01). In contrast, there was no effect for dorsal/pregenual anterior cingulate cortex activation (rs[38] = 0.18, p = 0.29), nor when using voxel-based whole-brain analyses (voxel-based Family-Wise Error-corrected p < 0.05). Predictive effects were mainly driven by the right amygdala whose response to happy faces was reduced in patients with higher anxiety levels.
Conclusions
We confirmed the prediction that a lower amygdala response to negative v. positive facial expressions might be an adaptive neural signature, which predicts subsequent symptom improvement also in difficult-to-treat MDD. Anxiety reduced adaptive amygdala responses.
The modulation of brain circuits of emotion is a promising pathway to treat borderline personality disorder (BPD). Precise and scalable approaches have yet to be established. Two studies investigating the amygdala-related electrical fingerprint (Amyg-EFP) in BPD are presented: one study addressing the deep-brain correlates of Amyg-EFP, and a second study investigating neurofeedback (NF) as a means to improve brain self-regulation.
Methods
Study 1 combined electroencephalography (EEG) and simultaneous functional magnetic resonance imaging to investigate the replicability of Amyg-EFP-related brain activation found in the reference dataset (N = 24 healthy subjects, 8 female; re-analysis of published data) in the replication dataset (N = 16 female individuals with BPD). In the replication dataset, we additionally explored how the Amyg-EFP would map to neural circuits defined by the research domain criteria. Study 2 investigated a 10-session Amyg-EFP NF training in parallel to a 12-weeks residential dialectical behavior therapy (DBT) program. Fifteen patients with BPD completed the training, N = 15 matched patients served as DBT-only controls.
Results
Study 1 replicated previous findings and showed significant amygdala blood oxygenation level dependent activation in a whole-brain regression analysis with the Amyg-EFP. Neurocircuitry activation (negative affect, salience, and cognitive control) was correlated with the Amyg-EFP signal. Study 2 showed Amyg-EFP modulation with NF training, but patients received reversed feedback for technical reasons, which limited interpretation of results.
Conclusions
Recorded via scalp EEG, the Amyg-EFP picks up brain activation of high relevance for emotion. Administering Amyg-EFP NF in addition to standardized BPD treatment was shown to be feasible. Clinical utility remains to be investigated.
Affiliating with delinquent peers may stimulate the development of antisocial behavior, especially for adolescents who are sensitive to social rewards. The current study examines whether the association between delinquent peer affiliation (DPA) and disruptive behavior interacts with functional brain correlates of reward sensitivity in early onset male adolescents delinquents.
Methods
Childhood arrestees (n = 126, mean age = 17.7 [s.d. 1.6]) completed a DPA questionnaire, and participated in an fMRI study in which reward sensitivity was operationalized through responsiveness of the ventral striatum (VS), amygdala, and medial prefrontal cortex (mPFC) during the monetary incentive delay paradigm (reward anticipation and outcome). Symptoms of disruptive behavior disorders (DBD) were assessed through structured psychiatric interviews (Diagnostic Interview Schedule for Children) with adolescents.
Results
DPA had a main effect on DBD symptoms. Adolescents with high VS reward responses showed a stronger significant positive association between DPA and DBD symptoms compared to low VS responders. No evidence for an interaction effect was found for the amygdala and mPFC. Post-hoc analyses revealed the positive association between DPA and DBD was only present in males, with a diminishing effect as age increased.
Conclusions
We found evidence for a biosocial interaction between DPA and reward sensitivity of the VS in relation to DBD symptom severity. This study provides the first evidence of an interaction effect between a brain mechanism and an environmental factor in relation to DBD symptoms, implying that susceptibility to influences of delinquent peers may intertwine with individual biological differences.
There are phenomenological similarities between social anxiety disorder (SAD) and posttraumatic stress disorder, such as a provoking aversive event, posttraumatic stress symptoms (e.g. intrusions) in response to these events and deficient (context-dependent) fear conditioning processes. This study investigated the neural correlates of context-dependent extinction recall and fear renewal in SAD, specifically in patients with intrusions in response to an etiologically relevant aversive social event.
Methods
During functional magnetic resonance imaging a two-day context-dependent fear conditioning paradigm was conducted in 54 patients with SAD and 54 healthy controls (HC). This included fear acquisition (context A) and extinction learning (context B) on one day, and extinction recall (context B) as well as fear renewal (contexts C and A) one day later. The main outcome measures were blood oxygen level-dependent responses in regions of interest and skin conductance responses.
Results
Patients with SAD showed reduced differential conditioned amygdala activation during extinction recall in the safe extinction context and during fear renewal in the acquisition context compared to HC. Patients with clinically relevant intrusions moreover exhibited hypoactivation of the ventromedial prefrontal cortex (vmPFC) during extinction learning, extinction recall, and fear renewal in a novel context, while amygdala activation more strongly decreased during extinction learning and increased during fear renewal in the acquisition context compared with patients without intrusions.
Conclusions
Our study provides first evidence that intrusions in SAD are associated with similar deficits in context-dependent regulation of conditioned fear via the vmPFC as previously demonstrated in posttraumatic stress disorder.
Examining neurobiological mechanisms that may transmit the effects of childhood maltreatment on mental health in youth is crucial for understanding vulnerability to psychopathology. This study investigated associations between childhood maltreatment, adolescent structural brain development, and mental health trajectories into young-adulthood.
Methods
Structural magnetic resonance imaging data was acquired from 144 youth at three time points (age 12, 16, and 18 years). Childhood maltreatment was reported to occur prior to the first scan. Linear mixed models were utilized to examine the association between total childhood maltreatment, neglect, abuse and (i) amygdala and hippocampal volume development, and (ii) maturational coupling between amygdala/hippocampus volume and the thickness of prefrontal regions. We also examined whether brain development mediated the association between maltreatment and depressive and anxiety symptoms trajectories from age 12 to 28.
Results
Total maltreatment, and neglect, were associated with positive maturational coupling between the amygdala and caudal anterior cingulate cortex (cACC), whereby at higher and lower levels of amygdala growth, maltreatment was associated with lower and higher PFC thinning, respectively. Neglect was also associated with maturational coupling of the hippocampus with prefrontal regions. While positive amygdala-cACC maturational coupling was associated with greater increases in anxiety symptoms, it did not significantly mediate the association between maltreatment and anxiety symptom trajectories.
Conclusion
We found maltreatment to be associated with altered patterns of coupling between subcortical and prefrontal regions during adolescence, suggesting that maltreatment is associated with the development of socio-emotional neural circuitry. The implications of these findings for mental health require further investigation.
Difficulties in the context-dependent modulation of conditioned fear are known for posttraumatic stress disorder and may explain the occurrence of intrusive memories in safe contexts. The current study therefore investigated if reduced context-dependent modulation of conditioned fear and its underlying neural circuitry constitute risk factors for the development of analog intrusions in response to an experimental trauma.
Methods
Eighty-five healthy women participated in the trauma film paradigm to investigate the development of analog intrusions as well as explicit memory for an experimental trauma after one week and three months, respectively. Before, participants underwent a context-dependent fear conditioning paradigm during functional magnetic resonance imaging with fear acquisition in context A and extinction training in context B on a first day, as well as extinction recall in context B and fear renewal in a novel context C one day later. Skin conductance responses (SCRs) and blood oxygen level dependent responses were main outcome measures.
Results
In addition to stronger fear acquisition in context A, stronger conditioned fear responses in the safe context B, as indicated by stronger conditioned SCRs or stronger activation of fear expressing regions during extinction learning and recall, predicted the development of long-term analog intrusions.
Conclusions
Stronger fear responses in safe and danger contexts were risk factors for the development of long-term analog intrusions and point to decontextualized fear memories and difficulties in the context-dependent modulation of conditioned fear. Altered fear conditioning processes and reduced storage of contextual information may cause the occurrence of fear independent of context.
Prenatal adversity has been linked to later psychopathology. Yet, research on cumulative prenatal adversity, as well as its interaction with offspring genotype, on brain and behavioral development is scarce. With this study, we aimed to address this gap. In Finnish mother–infant dyads, we investigated the association of a cumulative prenatal adversity sum score (PRE-AS) with (a) child emotional and behavioral problems assessed with the Strengths and Difficulties Questionnaire at 4 and 5 years (N = 1568, 45.3% female), (b) infant amygdalar and hippocampal volumes (subsample N = 122), and (c) its moderation by a hippocampal-specific coexpression polygenic risk score based on the serotonin transporter (SLC6A4) gene. We found that higher PRE-AS was linked to greater child emotional and behavioral problems at both time points, with partly stronger associations in boys than in girls. Higher PRE-AS was associated with larger bilateral infant amygdalar volumes in girls compared to boys, while no associations were found for hippocampal volumes. Further, hyperactivity/inattention in 4-year-old girls was related to both genotype and PRE-AS, the latter partially mediated by right amygdalar volumes as preliminary evidence suggests. Our study is the first to demonstrate a dose-dependent sexually dimorphic relationship between cumulative prenatal adversity and infant amygdalar volumes.
The amygdala is a subcortical limbic structure consisting of histologically and functionally distinct subregions. New automated structural magnetic resonance imaging (MRI) segmentation tools facilitate the in vivo study of individual amygdala nuclei in clinical populations such as patients with anorexia nervosa (AN) who show symptoms indicative of limbic dysregulation. This study is the first to investigate amygdala nuclei volumes in AN, their relationships with leptin, a key indicator of AN-related neuroendocrine alterations, and further clinical measures.
Methods
T1-weighted MRI scans were subsegmented and multi-stage quality controlled using FreeSurfer. Left/right hemispheric amygdala nuclei volumes were cross-sectionally compared between females with AN (n = 168, 12–29 years) and age-matched healthy females (n = 168) applying general linear models. Associations with plasma leptin, body mass index (BMI), illness duration, and psychiatric symptoms were analyzed via robust linear regression.
Results
Globally, most amygdala nuclei volumes in both hemispheres were reduced in AN v. healthy control participants. Importantly, four specific nuclei (accessory basal, cortical, medial nuclei, corticoamygdaloid transition in the rostral-medial amygdala) showed greater volumetric reduction even relative to reductions of whole amygdala and total subcortical gray matter volumes, whereas basal, lateral, and paralaminar nuclei were less reduced. All rostral-medially clustered nuclei were positively associated with leptin in AN independent of BMI. Amygdala nuclei volumes were not associated with illness duration or psychiatric symptom severity in AN.
Conclusions
In AN, amygdala nuclei are altered to different degrees. Severe volume loss in rostral-medially clustered nuclei, collectively involved in olfactory/food-related reward processing, may represent a structural correlate of AN-related symptoms. Hypoleptinemia might be linked to rostral-medial amygdala alterations.
So far, this book has focused on cognitive aspects of the mind. This chapter introduces the emerging area of affective science and emotion studies, which has gathered impetus in recent years. The first section reviews early theories of human emotions from Herbert Simon and Paul Ekman. The second section looks at how affective scientists explore emotions from a multidimensional perspective, introducing some new techniques in affective neuroscience. The last section draws the different strands together through the case study of fear, looking in particular at the neurobiology and neuroscience of fear.
Childhood trauma influences the clinical features of schizophrenia. In this study, we examined how childhood trauma and perceived stress are associated with clinical manifestations and subcortical gray matter volumes (GMVs) in patients with schizophrenia.
Methods
We recruited 127 patients with schizophrenia and 83 healthy controls for assessment of early childhood trauma, perceived stress, and clinical symptoms. With structural brain imaging, we identified the GMVs of subcortical structures and examined the relationships between childhood trauma, perceived stress, clinical symptoms, and subcortical GMVs.
Results
Compared to controls, patients with schizophrenia showed higher levels of childhood trauma and perceived stress. Patients with schizophrenia showed significantly smaller amygdala and hippocampus GMVs as well as total cortical GMVs than age-matched controls. Childhood trauma score was significantly correlated with the severity of clinical symptoms, depression, perceived stress, and amygdala GMVs. Perceived stress was significantly correlated with clinical symptoms, depression, and hippocampus and amygdala GMVs. Further, the association between childhood trauma (emotional neglect) and stress coping ability was mediated by right amygdala GMV in patients with schizophrenia.
Conclusions
Patients with schizophrenia had more exposure to early-life trauma and poorer stress coping. Both childhood trauma and perceived stress were associated with smaller amygdala volumes. The relationship between early-life trauma and perceived stress was mediated by right amygdala GMV in patients with schizophrenia. These findings together suggest the long-term effects of childhood trauma on perceived stress and the subcortical volumetric correlates of the effects in schizophrenia.
Psychosocial stressors characterized by social threat, such as interpersonal loss and social rejection, are associated with depression in adolescents. Few studies, however, have examined whether social threat affects fronto-cingulate-limbic systems implicated in adolescent depression.
Methods
We assessed lifetime stressor severity across several domains using the Stress and Adversity Inventory (STRAIN) in 57 depressed adolescents (16.15 ± 1.32 years, 34 females), and examined whether the severity of social threat and non-social threat stressors was associated with gray matter volumes (GMVs) in the anterior cingulate cortex (ACC), amygdala, hippocampus, and nucleus accumbens (NAcc). We also examined how lifetime social threat severity and GMVs in these regions related to depressive symptoms at baseline and over 9 months.
Results
General stressor severity was related to greater depression severity at baseline and over 9 months. Moreover, greater severity of social threat (but not non-social threat) stressors was associated with smaller bilateral amygdala and NAcc GMVs, and smaller bilateral surface areas of caudal and rostral ACC (all pFDR ⩽ 0.048). However, neither social threat nor non-social threat stressor severity was related to hippocampal GMVs (all pFDR ⩾ 0.318). All fronto-cingulate-limbic structures that were associated with the severity of social threat were negatively associated with greater depression severity over 9 months (all pFDR ⩽ 0.014). Post-hoc analyses suggested that gray matter morphometry of bilateral amygdala, NAcc, and rostral and caudal ACC mediated the association between social threat and depression severity in adolescents over 9 months (all pFDR < 0.048).
Conclusions
Social threat specifically affects fronto-cingulate-limbic pathways that contribute to the maintenance of depression in adolescents.
The thalamus traditionally is divided into the dorsal and ventral divisions, with both divisions divided into groups of nuclei. More recent approaches have defined divisions based on functional features, development, and/or evolutionary relationships. The thalamic nuclei are inextricably related to the corresponding divisions of the telencephalon, which is now recognized to have four developmental pallial sectors (the medial sector–derived hippocampal cortices; dorsal sector–derived neocortex; and lateral and ventral sector–derived claustrum, pallial amygdala, and related lateral nuclei in mammals) and the subpallium (which includes the septal nuclei, subpallial amygdala, and basal ganglia in mammals). The two evolutionary divisions of the dorsal thalamus, present in all jawed vertebrates, are the lemnothalamus and collothalamus. In amniotes, elaboration of different pallial sectors and their related dorsal thalamic nuclei was divergent, with the lemnothalamic-related, allocentric spatial mapping abilities selected for early in the line to mammals and the collothalamic-related, egocentric spatial mapping abilities selected for early in the line to reptiles, including birds. Secondarily, the collothalamic system was elaborated in mammals (e.g., LP/pulvinar in primates) and the lemnothalamic system in reptiles (e.g., primary visual and somatosensory nuclei in birds). Commonalities of thalamotelencephalic circuit motifs evolved in both lineages, supporting the functions of complex cognition and consciousness.
Projection neurons are both the main target of inputs to the thalamus and the only conduit for thalamic outputs. Projection neurons show similar somatodendritic morphologies, electrotonic properties, and membrane conductances, and they are all glutamatergic. Moreover, their axons never cross the midline and always target both the prethalamic reticular nucleus and one or more forebrain structures, chiefly the cerebral cortex and/or striatum. Despite these similarities, however, new anatomical, electrophysiological, and transcriptomic methods with single-cell resolution have in recent years revealed that thalamic projection neurons are remarkably diverse. Differences prominently involve axon arborization and gene-expression patterns, but significant variations in somatodendritic morphology and membrane conductances are also evident. Here, I first review the structural, functional, and gene-expression single-cell level variation observed among thalamic projection neurons. Then, based on evidence currently available for rodents, I propose a tentative catalog of six high-level cell classes. This catalog provides a consistent and cellularly accurate framework for the analysis of classic, large-scale thalamic output pathways such as the thalamocortical, thalamostriatal, and thalamoamygdaloid, among others. Moreover, developmental studies suggest that the neuron classes identified here may reflect a fundamental level of cell-lineage diversity that precedes nuclei formation or the establishment of thalamus connection systems.
Childhood maltreatment (CM) represents a potent risk factor for major depressive disorder (MDD), including poorer treatment response. Altered resting-state connectivity in the fronto-limbic system has been reported in maltreated individuals. However, previous results in smaller samples differ largely regarding localization and direction of effects.
Methods
We included healthy and depressed samples [n = 624 participants with MDD; n = 701 healthy control (HC) participants] that underwent resting-state functional MRI measurements and provided retrospective self-reports of maltreatment using the Childhood Trauma Questionnaire. A-priori defined regions of interest [ROI; amygdala, hippocampus, anterior cingulate cortex (ACC)] were used to calculate seed-to-voxel connectivities.
Results
No significant associations between maltreatment and resting-state connectivity of any ROI were found across MDD and HC participants and no interaction effect with diagnosis became significant. Investigating MDD patients only yielded maltreatment-associated increased connectivity between the amygdala and dorsolateral frontal areas [pFDR < 0.001; η2partial = 0.050; 95%-CI (0.023–0.085)]. This effect was robust across various sensitivity analyses and was associated with concurrent and previous symptom severity. Particularly strong amygdala-frontal associations with maltreatment were observed in acutely depressed individuals [n = 264; pFDR < 0.001; η2partial = 0.091; 95%-CI (0.038–0.166)). Weaker evidence – not surviving correction for multiple ROI analyses – was found for altered supracallosal ACC connectivity in HC individuals associated with maltreatment.
Conclusions
The majority of previous resting-state connectivity correlates of CM could not be replicated in this large-scale study. The strongest evidence was found for clinically relevant maltreatment associations with altered adult amygdala-dorsolateral frontal connectivity in depression. Future studies should explore the relevance of this pathway for a maltreated subgroup of MDD patients.
Bowlby proposed that the child forms a working model of the relationship between his/herself and caregivers. Where there is abuse, the working model represents this. In response, the child can learn to perform aggressive behaviour. A common feature of serial lust killers is that they experienced humiliation in their early lives. Early sources of abuse include physical, psychological and sexual. Later sources of trauma include taunting over sexual orientation and failure to find a girlfriend. Somewhat similar to the notion of ‘working model’ is that of a ‘love map’. The love map can be corrupted so that violence becomes encoded. The process of sensory preconditioning is under the control of dopamine and is responsible for forming links between an aversive emotion and sexual desire. In some cases, a traumatic memory can be revised to take on positive qualities and underlie lust killing. The Old Brain matures faster than the New Brain.
Although many previous studies reported structural plasticity of the hippocampus and amygdala induced by electroconvulsive therapy (ECT) in major depressive disorder (MDD), yet the exact roles of both areas for antidepressant effects are still controversial.
Methods
In the current study, segmentation of amygdala and hippocampal sub-regions was used to investigate the longitudinal changes of volume, the relationship between volume and antidepressant effects, and prediction performances for ECT in MDD patients before and after ECT using two independent datasets.
Results
As a result, MDD patients showed selectively and consistently increased volume in the left lateral nucleus, right accessory basal nucleus, bilateral basal nucleus, bilateral corticoamygdaloid transition (CAT), bilateral paralaminar nucleus of the amygdala, and bilateral hippocampus-amygdala transition area (HATA) after ECT in both datasets, whereas marginally significant increase of volume in bilateral granule cell molecular layer of the head of dentate gyrus, the bilateral head of cornu ammonis (CA) 4, and left head of CA 3. Correlation analyses revealed that increased volume of left HATA was significantly associated with antidepressant effects after ECT. Moreover, volumes of HATA in the MDD patients before ECT could be served as potential biomarkers to predict ECT remission with the highest accuracy of 86.95% and 82.92% in two datasets (The predictive models were trained on Dataset 2 and the sensitivity, specificity and accuracy of Dataset 2 were obtained from leave-one-out-cross-validation. Thus, they were not independent and very likely to be inflated).
Conclusions
These results not only suggested that ECT could selectively induce structural plasticity of the amygdala and hippocampal sub-regions associated with antidepressant effects of ECT in MDD patients, but also provided potential biomarkers (especially HATA) for effectively and timely interventions for ECT in clinical applications.
Borderline personality disorder (BPD) is associated with altered activity in the prefrontal cortex (PFC) and amygdala, yet no studies have examined fronto-limbic circuitry in borderline adolescents and emerging adults. Here, we examined the contribution of fronto-limbic effective connectivity (EC) to the longitudinal stability of emotion-related impulsivity, a key feature of BPD, in symptomatic adolescents and young adults.
Methods
We compared resting-state EC in 82 adolescents and emerging adults with and without clinically significant borderline symptoms (n BPD = 40, ages 13–30). Group-specific directed networks were estimated amongst fronto-limbic nodes including PFC, ventral striatum (VS), central amygdala (CeN), and basolateral amygdala (BLA). We examined the association of directed centrality metrics with initial levels and rates of change in emotion-related impulsivity symptoms over a one-year follow-up using latent growth curve models (LGCMs).
Results
In controls, ventromedial prefrontal cortex (vmPFC) and dorsal ACC had a directed influence on CeN and VS, respectively. In the BPD group, bilateral BLA had a directed influence on CeN, whereas in the healthy group CeN influenced BLA. LGCMs indicated that emotion-related impulsivity was stable across a one-year follow-up in the BPD group. Further, higher EC of R CeN to other regions in controls was associated with stronger within-person decreases in emotion-related impulsivity.
Conclusions
Functional inputs from BLA and vmPFC appear to play competing roles in influencing CeN activity. In borderline adolescents and young adults, BLA may predominate over CeN activity, while in controls the ability of CeN to influence BLA activity predicted more rapid reductions in emotion-related impulsivity.
Understanding when to trust and establishing judgments of trustworthiness are complex processes that are critical and essential for human life. Appropriate judgments in trustworthiness lead to the formation of cooperative, mutually beneficial relationships that facilitate personal success, a sense of achievement, increased well-being, and quality of life. The trust game is an economic decision-making game that was specifically designed to measure trust. It is an important and unique instrument, as it measures the entirety of the trust process. Research investigating brain activation during participation of the trust game has shown many brain regions and networks involved in the processes of trust. Whether some of these regions are necessary for various trust processes has been determined by studying trust game performances in individuals with lesions in specific trust-related brain areas. This chapter reviews lesion studies in patients with damage to the insula, amygdala, and prefrontal cortex, with a focus on how such patients perform on various aspects of the trust game and how the findings have informed our understanding of the neuroanatomical correlates of trust. Additionally, we review briefly some functional neuroimaging research on the involvement of the temporal parietal junction and ventral striatum in the trust process.
Despite nonoverlapping diagnostic criteria, internalizing and externalizing disorders show substantial comorbidity. This comorbidity is attributable, at least in part, to transdiagnostic neuroaffective mechanisms. Both unipolar depression and externalizing disorders are characterized by structural and functional compromises in the striatum and its projections to the anterior cingulate cortex (ACC) and other frontal regions. Smaller volumes and dampened reward responding in these regions are associated with anhedonia and irritability – mood states that cut across the internalizing and externalizing spectra. In contrast, smaller amygdala volumes and dampened amygdala function differentiate externalizing disorders from internalizing disorders. Little is known, however, about associations between internalizing–externalizing comorbidity and brain volumes in these regions, or whether such patterns differ by sex. Using a transdiagnostic, research domain criteria (RDoC)-informed approach, we evaluate associations between heterotypic (Internalizing × Externalizing) symptom interactions and striatal, amygdalar, and ACC volumes among participants in the Adolescent Brain Cognitive Development study (N = 6,971, mean age 9.9 years, 51.6% female). Heterotypic symptoms were associated with ACC volumes for both sexes, over and above the main effects of internalizing and externalizing alone. However, heterotypic comorbidity was associated with larger ACC volumes for girls, but with smaller ACC volumes for boys. These findings suggest a need for further studies and transdiagnostic assessment by sex.