Relationship of recent stress to amygdala volume in depressed and healthy adults

Sex differences in the relationship between brain gray matter volume and psychological resilience in late adolescence

Psychological resilience reflects an individual's ability to adapt and cope successfully in adverse environments and situations, making it a crucial trait in resisting stress-linked mental disorders and physical diseases. Although prior literature has consistently shown that males are more resilient than females, the sex-linked neuroanatomical correlates of psychological resilience are largely unknown. This study aims to explore the sex-specific relation between psychological resilience and brain gray matter volume (GMV) in adolescents via structural magnetic resonance imaging (s-MRI). A cohort of 231 healthy adolescents (121/110 females/males), aged 16 to 20 completed brain s-MRI scanning and Connor-Davidson Resilience Scale (CD-RISC) and other controlling behavioral tests. With s-MRI data, an optimized voxel-based morphometry method was used to estimate regional GMV, and a whole-brain condition-by-covariate interaction analysis was performed to identify the brain regions showing sex effects on the relation between psychological resilience and GMV. Male adolescents scored significantly higher than females on the CD-RISC. The association of psychological resilience with GMV differed between the two sex groups in the left ventrolateral prefrontal cortex extending to the adjacent anterior insula, with a positive correlation among males and a negative correlation among females. The sex-specific association between psychological resilience and GMV might be linked to sex differences in the hypothalamic-pituitary-adrenal axis and brain maturation during adolescence. This study may be novel in revealing the sex-linked neuroanatomical basis of psychological resilience, highlighting the need for a more thorough investigation of the role of sex in future studies of psychological resilience and stress-related illness.

Alterations of amygdala volume and functional connectivity in migraine patients comorbid with and without depression

OBJECTIVE

The comorbid relationship between migraine and depression has been well recognized, but its underlying pathophysiology is unclear. Here, we aimed to explore the structural changes of the amygdala and the abnormal functional connectivity of the centromedial amygdala (CMA) in migraineurs with depression.

METHODS

High-resolution T1-weighted and functional magnetic resonance images were acquired from 22 episodic migraineurs with comorbid depression (EMwD), 21 episodic migraineurs without depression (EM), and 17 healthy controls (HC). Voxel-based morphometry and resting-state functional connectivity (rsFC) were applied to examine the intergroup differences in amygdala volume.

RESULTS

The bilateral amygdala volume was increased in the EMwD and EM groups compared with the HC group, but there were no differences between the EMwD and EM groups. The right CMA exhibited decreased rsFC in the left dorsolateral prefrontal cortex (DLPFC) in the EMwD group compared with the EM group, while rsFC increased between the CMA and the contralateral DLPFC in the EM group compared with the HC group. In addition, the EM group showed decreased rsFC between the left CMA and the left pallidum compared with the HC group.

CONCLUSIONS

Enlarged amygdala is an imaging feature of EM and EMwD. The inconsistency of rsFC between CMA and DLPFC between migraineurs with and without depression might indicate that decreased rsFC between CMA and DLPFC is a neuropathologic marker for the comorbidity of migraine and depression. The core regions might be a potential intervention target for the treatment of EMwD in the future.

Hippocampal subfield volumes predict treatment response to oral ketamine in people with suicidality

Ongoing stress results in hippocampal neuro-structural alterations which produce pathological consequences, including depression and suicidality. Ketamine may ameliorate stress related illnesses, including suicidality, via neuroplasticity processes. This novel study sought to determine whether oral ketamine treatment specifically affects hippocampal (whole and subfield) volumes in patients with chronic suicidality and MDD. It was hypothesised that oral ketamine treatment would differentially alter hippocampal volumes in trial participants categorised as ketamine responders, versus those who were non-responders. Twenty-eight participants received 6 single, weekly doses of oral ketamine (0.5-3 mg/kg) and underwent MRI scans at pre-ketamine (week 0), post-ketamine (week 6), and follow up (week 10). Hippocampal subfield volumes were extracted using the longitudinal pipeline in FreeSurfer. Participants were grouped according to ketamine response status and then compared in terms of grey matter volume (GMV) changes, among 10 hippocampal regions, over 6 and 10 weeks. Mixed ANOVAs were used to analyse interactions between time and group. Post treatment analysis revealed a significant main effect of group for three left hippocampal GMVs as well in the left and right whole hippocampus. Ketamine acute responders (Week 6) showed increased GMVs in both left and right whole hippocampus and in three subfields compared to acute non-responders, across all three timepoints, suggesting that pre-treatment increased hippocampal GMVs (particularly left hemisphere) may be predictive biomarkers of acute treatment response. Future studies should further investigate the potential of hippocampal volumes as a biomarker of ketamine treatment response.

Major gender differences in relations between life stressor frequency and gray matter in adolescence and emerging adulthood

Adolescence and emerging adulthood is likely a sensitive period for the neural effects of stress due to increasing life stress, onset of stress-related disorders, and continued gray matter (GM) development. In adults, stress is associated with GM differences in the medial prefrontal cortex (mPFC), hippocampus, and amygdala, but little is known about these relations, and whether they differ by gender, during adolescence and emerging adulthood. Further, it is unknown whether dependent (self-generated) and independent (fateful) stressors have distinct associations with GM, as each have distinct relations with internalizing psychopathology. We tested relations between recent dependent and independent stressor frequency (ALEQ-R) and GM structure using MRI in a priori regions of interest (mPFC, amygdala, and hippocampus) and across the cortex in youth from the Denver/Boulder metro area ages 14-22 (N = 144). Across both genders, no effects passed multiple comparison correction (FDR q > .05). However, there were significant differences between male and female youth (FDR q < .05), with opposite relations between dependent stressor frequency and cortical GM thickness in the salience network and emotion regulation regions and with surface area in default mode network regions. These results motivate future investigations of gender differences in neural mechanisms of stress generation and reactivity. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Prefrontal Cortex Volume Mediates the Relationship Between Lifetime Chronic Stressor Exposure and Cognition in People Living With and Without HIV

OBJECTIVE

Despite considerable research documenting how stress affects brain and neurobehavioral outcomes, few studies have assessed stressor exposure occurring over the entire life span, and no studies have investigated these associations in people living with HIV (PLWH), despite the high stress and disease burden experienced by this population. To address this issue, we examined how cumulative lifetime chronic stressor exposure related to cognition and brain integrity (i.e., gray matter volume) in White and African American PLWH and HIV-uninfected (HIV-) adults.

METHOD

Participants were 91 community-dwelling adults (47.3% PLWH) who completed a comprehensive interview assessing lifetime stressor exposure using the Stress and Adversity Inventory and underwent neuropsychological testing and structural magnetic resonance imaging. Regional brain volumes were derived from T1-weighted images processed through Freesurfer.

RESULTS

As hypothesized, greater lifetime chronic stressor exposure was related to worse global cognition ( b = -0.06, standard error [SE] = 0.03, p = .032), processing speed ( b = -0.04, SE = 0.14, p = .041), and executive functioning ( b = -0.06, SE = 0.02, p = .02), and smaller prefrontal cortex (PFC) volume ( b = -16.20, SE = 5.78, p = .007). HIV status did not moderate any of these associations. Moreover, results from mediation analyses demonstrated that the relationship between lifetime chronic stressor exposure and processing speed was fully mediated by PFC volume.

CONCLUSIONS

These results highlight the critical role of the PFC in the maintenance of processing speed abilities and its vulnerability to cumulative stressor exposure. Specifically, the negative impact of lifetime chronic stressor exposure on cognition-particularly functions reliant on frontal lobe integrity-may be partly driven by smaller volumes in the PFC.

Association of amygdala size with stress perception: Findings of a transversal study across the lifespan

Daily routines are getting increasingly stressful. Interestingly, associations between stress perception and amygdala volume, a brain region implicated in emotional behaviour, have been observed in both younger and older adults. Life stress, on the other hand, has become pervasive and is no longer restricted to a specific age group or life stage. As a result, it is vital to consider stress as a continuum across the lifespan. In this study, we investigated the relationship between perceived stress and amygdala size in 272 healthy participants with a broad age range. Participants were submitted to a structural magnetic resonance imaging (MRI) to extract amygdala volume, and the Perceived Stress Scale (PSS) scores were used as the independent variable in volumetric regressions. We found that perceived stress is positively associated with the right amygdala volume throughout life.

Neuroanatomical Correlates of Perceived Stress Controllability in Adolescents and Emerging Adults

Stressful life events predict changes in brain structure and increases in psychopathology, but not everyone is equally affected by life stress. The learned helplessness theory posits that perceiving life stressors as uncontrollable leads to depression. Evidence supports this theory for youth, but the impact of perceived control diverges based on stressor type: perceived lack of control over dependent (self-generated) stressors is associated with greater depression symptoms when controlling for the frequency of stress exposure, but perceived control over independent (non-self-generated) stressors is not. However, it is unknown how perceived control over these stressor types is associated with brain structure. We tested whether perceived lack of control over dependent and independent life stressors, controlling for stressor exposure, is associated with gray matter (GM) in a priori regions of interest (ROIs; mPFC, hippocampus, amygdala) and across the cortex in a sample of 108 adolescents and emerging adults ages 14-22. There were no associations across the full sample between perceived control over either stressor type and GM in the ROIs. However, less perceived control over dependent stressors was associated with greater amygdala gray matter volume in female youth and greater medial prefrontal cortex thickness in male youth. Furthermore, whole-cortex analyses revealed less perceived control over dependent stressors was associated with greater GM thickness in cortical regions involved in cognitive and emotional regulation. Thus, appraisals of control have distinct associations with brain morphology while controlling for stressor frequency, highlighting the importance of differentiating between these aspects of the stress experience in future research.

Alterations in CRY2 and PER3 gene expression associated with thalamic-limbic community structural abnormalities in patients with bipolar depression or unipolar depression

Objectives The current study aimed to identify shared and distinct brain structure abnormalities and their relationships with the expression of circadian genes in patients with bipolar or unipolar depression. Method A total of 93 subjects participated in this study, including 32 patients with bipolar depression (BDP), 26 patients with unipolar depression (UDP) and 35 age- and sex-matched healthy controls. Brain structural magnetic resonance imaging scans were obtained, and optimized voxel-based morphometry was used to explore group differences in regional gray matter volume (GMV). The mRNA expression levels of circadian genes in peripheral blood were measured using reverse transcription quantitative real-time polymerase chain reaction. Results Our results showed that the GMV in brain regions in the thalamus-limbic pathways had significantly increased in the BDP patients compared to controls, while the increased GMV in UDP patients compared to controls was limited to the thalamus. The mRNA expression levels of circadian-related genes decreased significantly in patients with BDP, but increased in patients with UDP, compared to controls. In addition, the GMV in the right thalamus in the patients with UDP was positively associated with mRNA levels of CRY2, while the GMV in the right hippocampus in the patients with BDP was negatively associated with mRNA levels of PER3. Conclusion Our study suggested that patients with BDP or MDD shared GMV abnormalities in the right thalamus. The PER3 and CRY2 genes might be critical to right hippocampal dysfunction in BDP and right thalamic dysfunction in UDP, respectively. The result provided potentially important molecular targets for the treatment of mood disorders.

Real-time individual benefit from social interactions before and during the lockdown: the crucial role of personality, neurobiology and genes

Social integration is a major resilience factor for staying healthy. However, the COVID-19-pandemic led to unprecedented restrictions in social life. The consequences of these social lockdowns on momentary well-being are yet not fully understood. We investigated the affective benefit from social interactions in a longitudinal birth cohort. We used two real-time, real-life ecological momentary assessments once before and once during the initial lockdown of the pandemic (N = 70 participants; n~6800 observations) capturing the protective role of social interactions on well-being. Moreover, we used a multimethod approach to analyze ecological assessment data with individual risk and resilience factors, which are promising moderators in the relationship of social behavior, stress reactivity, and affective states (i.e., amygdala volume, neuroticism, polygenic risk for schizophrenia). Social contacts were linked to higher positive affect both during normal times and during the COVID-19-pandemic (beta coefficient = 0.1035), highlighting the beneficial role of social embedding. Interestingly, this relationship was differentially moderated by individual risk and resilience factors. In detail, participants with a larger left amygdala volume (beta coefficient = -0.0793) and higher neuroticism (beta coefficient = -0.0958) exhibited an affective benefit from more social interactions prior to the pandemic. This pattern changed during the pandemic with participants with smaller amygdala volumes and lower neurotic traits showing an affective gain during the pandemic. Moreover, participants with low genetic risk for schizophrenia showed an affective benefit (beta coefficient = -0.0528) from social interactions irrespective of the time point. Our results highlight the protective role of social integration on momentary well-being. Thereby, we offer new insights into how this relationship is differently affected by a person's neurobiology, personality, and genes under adverse circumstances.

Mini-review: Elucidating the psychological, physical, and sex-based interactions between HIV infection and stress

Stress is generally classified as any mental or emotional strain resulting from difficult circumstances, and can manifest in the form of depression, anxiety, post-traumatic stress disorder (PTSD), or other neurocognitive disorders. Neurocognitive disorders such as depression, anxiety, and PTSD are large contributors to disability worldwide, and continue to affect individuals and communities. Although these disorders affect men and women, women are disproportionately represented among those diagnosed with affective disorders, a result of both societal gender roles and physical differences. Furthermore, the incidence of these neurocognitive disorders is augmented among People Living with HIV (PLWH); the physical ramifications of stress increase the likelihood of HIV acquisition, pathogenesis, and treatment, as both stress and HIV infection are characterized by chronic inflammation, which creates a more opportunistic environment for HIV. Although the stress response is facilitated by the autonomic nervous system (ANS) and the hypothalamic pituitary adrenal (HPA) axis, when the response involves a psychological component, additional brain regions are engaged. The impact of chronic stress exposure and the origin of individual variation in stress responses and resilience are at least in part attributable to regions outside the primary stress circuity, including the amygdala, prefrontal cortex, and hippocampus. This review aims to elucidate the relationship between stress and HIV, how these interact with sex, and to understand the physical ramifications of these interactions.

How stress physically re-shapes the brain: Impact on brain cell shapes, numbers and connections in psychiatric disorders

Severe stress is among the most robust risk factors for the development of psychiatric disorders. Imaging studies indicate that life stress is integral to shaping the human brain, especially regions involved in processing the stress response. Although this is likely underpinned by changes to the cytoarchitecture of cellular networks in the brain, we are yet to clearly understand how these define a role for stress in human psychopathology. In this review, we consolidate evidence of macro-structural morphometric changes and the cellular mechanisms that likely underlie them. Focusing on stress-sensitive regions of the brain, we illustrate how stress throughout life may lead to persistent remodelling of the both neurons and glia in cellular networks and how these may lead to psychopathology. We support that greater translation of cellular alterations to human cohorts will support parsing the psychological sequalae of severe stress and improve our understanding of how stress shapes the human brain. This will remain a critical step for improving treatment interventions and prevention outcomes.

Hippocampal and Amygdalar Volume Changes in Major Depressive Disorder: A Targeted Review and Focus on Stress

Medial temporal lobe structures have long been implicated in the pathogenesis of major depressive disorder. Although findings of smaller hippocampal and amygdalar volumes are common, inconsistencies remain in the literature. In this targeted review, we examine recent and significant neuroimaging papers examining the volumes of these structures in major depressive disorder. A targeted PubMed/Google Scholar search was undertaken focusing on volumetric neuroimaging studies of the hippocampus and amygdala in major depressive disorder. Where possible, mean volumes and accompanying standard deviations were extracted allowing computation of Cohen’s d_s effect sizes. Although not a meta-analysis, this allows a broad comparison of volume changes across studies. Thirty-nine studies in total were assessed. Hippocampal substructures and amygdale substructures were investigated in 11 and 2 studies, respectively. The hippocampus was more consistently smaller than the amygdala across studies, which is reflected in the larger cumulative difference in volume found with the Cohen’s d_s calculations. The left and right hippocampi were, respectively, 92% and 91.3% of the volume found in controls, and the left and right amygdalae were, respectively, 94.8% and 92.6% of the volume of controls across all included studies. The role of stress in temporal lobe structure volume reduction in major depressive disorder is discussed.

Smaller left hippocampal subfield CA1 volume is associated with reported childhood physical and/or sexual abuse in major depression: A pilot study

BACKGROUND

Smaller hippocampal volumes are reported in adults with major depressive disorder (MDD) and in reported childhood abuse. The hippocampus is a complex structure with distinct functional subfields. We sought to examine the effect of MDD diagnosis and childhood abuse on hippocampal subfields.

METHODS

Forty-one MDD participants (17 reported abuse and 24 did not) and 46 healthy volunteers (HV) (2 reported abuse) underwent T1- weighted structural magnetic resonance imaging (MRI) and clinical characterization in a retrospective design. A subfield segmentation program was used to measure the whole and subfield hippocampal volumes. Linear mixed-effects models were fitted for group comparisons.

RESULTS

No main effect of diagnosis interaction effect between diagnosis and subfield region was observed. However, a comparison of abused MDD vs. HVs showed a group by region interaction. A significant interaction between childhood abuse and region was observed. Effects were confined to the left side of the brain, and post hoc, exploratory region-specific tests indicated smaller left CA1 volume in abused MDD compared with non-abused MDD. In addition, smaller amygdala volume was found in all MDD compared with HVs.

LIMITATIONS

We did not have a sample of healthy volunteers with reported childhood abuse.

CONCLUSIONS

The diagnosis of pure MDD may not be sufficient to exert effects on hippocampal volumes, indicating the importance of taking into account childhood trauma in studies on psychopathological mechanisms. Left CA1 might be the hippocampal subfield most relevant to reported childhood abuse. Smaller amygdala volume may be related to MDD diagnosis independent of childhood abuse.

Macro- and microstructural gray matter alterations in sexually assaulted women

BACKGROUND

Studies with trauma survivors documented structural alterations in brain regions involved in posttraumatic stress disorder (PTSD) neurocircuitry. Nonetheless, whether such alterations exist in women who were sexually assaulted in adulthood is not clear. We investigated the macro- and microstructure of key regions implicated in PTSD pathophysiology, namely the amygdala, hippocampus, anterior cingulate cortex (ACC), and insula, in this population.

METHODS

Thirty-eight sexually assaulted women (PTSD, n = 25; non-PTSD, n = 13) and 24 non-exposed controls (NEC) were studied with T1- and diffusion-weighted MRI. Gray matter volume, mean diffusivity (MD), and fractional anisotropy (FA) were calculated for each region. Between-group comparisons and correlations with PTSD symptom severity were performed.

RESULTS

Volumetric analyses revealed lower amygdala and insula volumes in the PTSD compared with the non-PTSD group. In contrast, altered microstructure was observed in both traumatized groups compared with NEC, including higher MD and lower FA in the right amygdala, and higher FA in the ACC bilaterally. Finally, the non-PTSD group had higher FA in the right insula compared with the PTSD group. PTSD symptom severity was correlated with amygdala and insula volumes, as well as with hippocampal FA and MD.

LIMITATIONS

Sample size may have led to reduced statistical power.

CONCLUSIONS

Sexual assault and the development of PTSD in women are linked with structural alterations in key regions implicated in PTSD following other trauma types (e.g., combat), though hippocampal and ACC volumes were preserved. Further studies are needed to disentangle the unique contribution of trauma type and of sex/gender to these observations.

Gender-specific differences in white matter microstructure in healthy adults exposed to mild stress

Stress is a powerful moderator of brain plasticity and may affect several physiological functions such as the endocrine and the immune system. The impact of stress can be protective or detrimental according to several factors such as level of the stressor and age of occurrence. Also, the impact may differ in males and females. We aim to analyze the effect of mild levels of early and recent stress on white matter microstructure in healthy volunteers. MRI acquisition of diffusion tensor images with a 3.0 T scanner was performed on 130 healthy subjects (71 males and 59 females). Severity of early and recent stress was rated, respectively, on the Risky Families Questionnaire and on the Schedule of Recent Experiences; subjects were divided into low stress and mild stress groups. Mild early stress associated with lower fractional anisotropy (FA) in the cingulate gyrus compared to low early stress. Females reported reduced FA compared to males in the low-stress group in the internal capsule, posterior corona radiata, posterior thalamic radiation, superior longitudinal fasciculus, and sagittal stratum whereas no difference was observed in the mild stress group. An additive effect of early and recent stress was observed in posterior corona radiata, retrolenticular part of the internal capsule, and superior longitudinal fasciculus. The impact of early stress on WM microstructure in healthy subjects is different in males and females. While males seem to be more sensitive to early stress, an additive effect of early and recent stress manifests itself in females.Layman summaryMild levels of early stress associate with lower white matter integrity measured by fractional anisotropy.Females and males show differences in white matter integrity when exposed to low levels of early stress with females showing lower white matter integrity compared to males.No difference in white matter integrity was observed for males and females exposed to mild levels of stress.Mild stress in females is associated with higher white matter integrity.Males seem to be more sensitive to early stress while females are more affected when early stress is followed by stress in adult life.

The Resilient Emotional Brain: A Scoping Review of the Medial Prefrontal Cortex and Limbic Structure and Function in Resilient Adults With a History of Childhood Maltreatment

Childhood maltreatment (CM) is one of the strongest predictors of adult mental illness, although not all adults with CM develop psychopathology. Here, we describe the structure and function of the emotional brain regions that may contribute to resilient functioning after CM. We review studies that report medial prefrontal cortex, amygdala, and hippocampus (limbic regions) structure, function, and/or connections in resilient adults (i.e., those reporting CM without psychopathology) versus vulnerable adults (i.e., those reporting CM with psychopathology) or healthy adults (those without CM and with no psychopathology). We find that resilient adults have larger hippocampal gray and white matter volume and greater connectivity between the central executive network and the limbic regions. In addition, resilient adults have improved ability to regulate emotions through medial prefrontal cortex-limbic downregulation, lower hippocampal activation to emotional faces, and increased amygdala habituation to stress. We highlight the need for longitudinal designs that examine resilient functioning across domains and consider gender, type, timing, and nature of CM assessments and further stressors to further improve our understanding of the role of the emotional brain in resilient functioning after CM.

Transdiagnostic neuroimaging in psychiatry: A review

Transdiagnostic approach has a long history in neuroimaging, predating its recent ascendance as a paradigm for new psychiatric nosology. Various psychiatric disorders have been compared for commonalities and differences in neuroanatomical features and activation patterns, with different aims and rationales. This review covers both structural and functional neuroimaging publications with direct comparison of different psychiatric disorders, including schizophrenia, bipolar disorder, major depressive disorder, autism spectrum disorder, obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, conduct disorder, anorexia nervosa, and bulimia nervosa. Major findings are systematically presented along with specific rationales for each comparison.

Abnormal intrinsic brain functional network dynamics in unmedicated depressed bipolar II disorder

BACKGROUND

Previous studies analyzed brain functional connectivity (FC) based on resting-state fMRI (RS-fMRI) data to reveal the neuropathology of bipolar disorder (BD) and suggested that their FC alterations are at widespread network-level. However, few studies have analyzed the dynamic functional network connectivity (dFNC) in BD. Thus, we aimed to reveal the dFNC properties of BD in this study.

METHODS

The RS-fMRI data were collected from 51 unmedicated depressed BD II patients and 50 healthy controls. We analyzed the dFNC properties by using an independent component analysis, sliding window correlation, k-means clustering, and graph theory methods.

RESULTS

The intrinsic brain FNC could be clustered into three configuration states, one with sparse connections between all functional networks (State 1), another with negative correlations between the salience network, cerebellum, basal ganglia and the sensory networks (State 2), and a third with negative correlations between the default mode network and the other functional networks (State 3). The BD patients had increased time in State 2, decreased time in State 3, and increased transition number between states. And the time spent in State 2 was positively correlated with the HDRS24 score in the BD patients. In addition, the BD patients had increased dynamic variance in the small-world properties of FNC.

LIMITATIONS

This study did not examine data from BD patients in other episodes and other BD types.

CONCLUSIONS

This study detected abnormal dFNC properties in BD, which indicated their FNC unstability and provided new insights into the neuropathology of their affective and cognitive deficits.

Differentiating between bipolar and unipolar depression in functional and structural MRI studies

Distinguishing depression in bipolar disorder (BD) from unipolar depression (UD) solely based on clinical clues is difficult, which has led to the exploration of promising neural markers in neuroimaging measures for discriminating between BD depression and UD. In this article, we review structural and functional magnetic resonance imaging (MRI) studies that directly compare UD and BD depression based on neuroimaging modalities including functional MRI studies on regional brain activation or functional connectivity, structural MRI on gray or white matter morphology, and pattern classification analyses using a machine learning approach. Numerous studies have reported distinct functional and structural alterations in emotion- or reward-processing neural circuits between BD depression and UD. Different activation patterns in neural networks including the amygdala, anterior cingulate cortex (ACC), prefrontal cortex (PFC), and striatum during emotion-, reward-, or cognition-related tasks have been reported between BD and UD. A stronger functional connectivity pattern in BD was pronounced in default mode and in frontoparietal networks and brain regions including the PFC, ACC, parietal and temporal regions, and thalamus compared to UD. Gray matter volume differences in the ACC, hippocampus, amygdala, and dorsolateral prefrontal cortex (DLPFC) have been reported between BD and UD, along with a thinner DLPFC in BD compared to UD. BD showed reduced integrity in the anterior part of the corpus callosum and posterior cingulum compared to UD. Several studies performed pattern classification analysis using structural and functional MRI data to distinguish between UD and BD depression using a supervised machine learning approach, which yielded a moderate level of accuracy in classification.

Impact of early and recent stress on white matter microstructure in major depressive disorder

BACKGROUND

Major Depressive Disorder (MDD) is a worldwide-spread pathology, characterized by lifetime-recurrent episodes. Adverse childhood experiences (ACE) increase the lifetime risk of developing depression and affect the structure of the brain. Recent stressful events (RSE) can trigger the onset of depressive episodes, and affect grey matter volume. The aim of our study is to analyse the effect of both early and recent stress events on white matter microstructure in MDD patients and healthy volunteers.

METHODS

Sixty-five MDD inpatients and fifty-nine healthy controls underwent MRI acquisition of diffusion tensor images with a 3.0T scanner. Severity of ACE and RSE was rated, respectively, on the Risky Families Questionnaire and on the Social Readjustment Rating Scale.

RESULTS

A significant effect of diagnosis was observed, with MDD subjects showing reduced fractional anisotropy (FA) and axial diffusivity (AD) compared to healthy controls in all the major association, projection and commissural tracts. In patients with MDD, but not in healthy controls, both ACE and RSE correlated with measures of WM microstructure: ACE correlated negatively with AD and MD, whereas RSE correlated negatively with FA.

LIMITATIONS

The two diagnostic groups differed for age and education, previous and current medications, and treatment periods.

CONCLUSIONS

Exposure to both early and recent stress exerts a widespread effect on WM microstructure of MDD patients, with a different impact possibly depending from the developmental period in which the stress has occurred.

Sex Differences in Trauma-Related Psychopathology: a Critical Review of Neuroimaging Literature (2014-2017)

PURPOSE OF REVIEW

Sex differences in the epidemiology and clinical presentation of trauma-related psychopathology have long been documented. Multiple underlying mechanisms have been examined, both psychosocial and biological. Among the most promising biological mechanisms are neural substrates of trauma-related psychopathology that have been uncovered in recent years.

RECENT FINDINGS

Neuroimaging studies of sex-related heterogeneity published over the past 3 years (2014-2017) demonstrate an interaction between sex and type, timing, and load of trauma exposure. These studies suggest that, for males, early trauma exposure may involve a loss of gray matter in the limbic system, including the prefrontal cortex (PFC), amygdala, and hippocampus, and an over-activity and increased connectivity of salience hubs, and particularly dorsal anterior cingulate cortex (dACC). For females, however, early trauma exposure may involve overactive and possibly an enlarged amygdala, as well as decreased connectivity of salience hubs such as the dACC. Underlying mechanisms may include interaction with several endocrine systems and result in differential neural response to naturally occurring and added endocrine ligands, as well as sex-specific genetic and epigenetic risk and resilience factors. This complex interaction between multiple biological systems may be associated with sex-specific behavioral patterns, in turn associated with trauma-related psychopathology. While substantial number of published studies present preliminary evidence for neural mechanisms of sex-specific posttraumatic responses, there is a paucity of research directly designed to examine sex as a biological factor in trauma-related psychopathology. Specific foci for future studies aiming to bridge current gaps in the literature are discussed.