Structure-function associations in hippocampus in bipolar disorder

Shared and Distinct Neurobiological Bases of Bipolar Disorder and Attention-Deficit/Hyperactivity Disorder in Children and Adolescents: A Comparative Meta-Analysis of Structural Abnormalities

OBJECTIVE

Pediatric bipolar disorder (PBD) and attention-deficit/hyperactivity disorder (ADHD) frequently co-occur and share dysfunctions in affective and cognitive domains. As the neural substrates underlying their overlapping and dissociable symptomatology have not been well delineated, a meta-analysis of whole-brain voxel-based morphometry studies in PBD and ADHD was conducted.

METHOD

A systematic literature search was performed in PubMed, Web of Science, and Embase. The seed-based d mapping toolbox was used to identify altered clusters of PBD or ADHD and obtain their conjunctive and comparative abnormalities. Suprathreshold patterns were subjected to large-scale network analysis to identify affected brain networks.

RESULTS

The search revealed 10 PBD studies (268 patients) and 32 ADHD studies (1,333 patients). Decreased gray matter volumes in the right insula and anterior cingulate cortex relative to typically developing individuals were conjunctive in PBD and ADHD. Reduced volumes in the right inferior frontal gyrus, left orbitofrontal cortex, and hippocampus were more substantial in PBD, while decreased volumes in the left precentral gyrus, left inferior frontal gyrus, and right superior frontal gyrus were more pronounced in ADHD. Neurodevelopmental effects modulated patterns of the left hippocampus in PBD and those of the left inferior frontal gyrus in ADHD.

CONCLUSION

These findings suggest that PBD and ADHD are characterized by both common and distinct patterns of gray matter volume alterations. Their overlapping abnormalities may represent a transdiagnostic problem of attention and emotion regulation shared by PBD and ADHD, whereas the disorder-differentiating substrates may contribute to the relative differences in cognitive and affective features that define the 2 disorders.

PLAIN LANGUAGE SUMMARY

Pediatric bipolar disorder (BD) and attention-deficit/hyperactivity disorder (ADHD) frequently co-occur, with overlapping changes in emotional and cognitive functioning. This meta-analysis summarizes findings from 10 articles on BD and 32 articles on ADHD to identify similarities and differences in brain structure between youth with BD and youth with ADHD. The authors found that both disorders share decreased gray matter volumes in the right insula and anterior cingulate cortex, which play important roles in emotion processing and attention, respectively. Youth with BD had decreased gray matter volume in the right inferior frontal gyrus, left orbitofrontal gyrus, and left hippocampus, while youth with ADHD had decreased volumes in the left precentral gyrus, left inferior frontal gyrus, and right superior frontal gyrus.

STUDY PREREGISTRATION INFORMATION

Structural Brain Abnormalities of Attention-Deficit/Hyperactivity Disorder and Bipolar Disorder in Children/Adolescents: An Overlapping Meta-analysis; https://osf.io; trg4m.

Distinguishing functional and structural MRI abnormalities between bipolar and unipolar depression

Background

This study aims to investigate the underlying characteristics of spontaneous brain activity by analyzing the volumes of the hippocampus and parahippocampal gyrus, as well as the fractional amplitude of low-frequency fluctuation (fALFF) and regional homogeneity (ReHo), in order to differentiate between bipolar disorder (BD) and unipolar depressive disorder.

Methods

A total of 46 healthy controls, 58 patients with major depressive disorder (MDD), and 61 patients with BD participated in the study and underwent resting-state functional magnetic resonance imaging (rs-fMRI) scans. The researchers calculated the differences in volume, fALFF, and ReHo values among the three groups. Additionally, they conducted correlation analyses to examine the relationships between clinical variables and the aforementioned brain measures.

Results

The results showed that the BD group exhibited increased fALFF in the hippocampus compared to the healthy control (HC) and MDD groups. Furthermore, the ReHo values in the hippocampus and parahippocampal gyrus were significantly higher in the BD group compared to the HC group. The findings from the person correlation analysis indicated a positive relationship between ReHo values in the hippocampus and both HAMD and HAMA scores. Moreover, there was no correlation between the volumes, fALFF, and ReHo values in the hippocampus and parahippocampal gyrus, and cognitive function levels (RBANS).

Conclusion

Taken together, these aberrant patterns of intrinsic brain activity in the hippocampus and parahippocampal gyrus may serve as quantitative indicators for distinguishing between BD and unipolar depression.

Hippocampal Dynamic Functional Connectivity, HPA Axis Activity, and Personality Trait in Bipolar Disorder with Suicidal Attempt

INTRODUCTION

Suicide in bipolar disorder (BD) is a multifaceted behavior, involving specific neuroendocrine and psychological mechanisms. According to previous studies, we hypothesized that suicidal BD patients may exhibit impaired dynamic functional connectivity (dFC) variability of hippocampal subregions and hypothalamic-pituitary-adrenal (HPA) axis activity, which may be associated with suicide-related personality traits. The objective of our study was to clarify this.

METHODS

Resting-state functional magnetic resonance imaging data were obtained from 79 patients with BD, 39 with suicidal attempt (SA), and 40 without SA, and 35 healthy controls (HCs). The activity of the HPA axis was assessed by measuring morning plasma adrenocorticotropic hormone (ACTH) and cortisol (CORT) levels. All participants underwent personality assessment using Minnesota Multiphasic Personality Inventory-2 (MMPI-2).

RESULTS

BD patients with SA exhibited increased dFC variability between the right caudal hippocampus and the left superior temporal gyrus (STG) when compared with non-SA BD patients and HCs. BD with SA also showed significantly lower ACTH levels in comparison with HCs, which was positively correlated with increased dFC variability between the right caudal hippocampus and the left STG. BD with SA had significantly higher scores of Hypochondriasis, Depression, and Schizophrenia than non-SA BD. Additionally, multivariable regression analysis revealed the interaction of ACTH × dFC variability between the right caudal hippocampus and the left STG independently predicted MMPI-2 score (depression evaluation) in suicidal BD patients.

CONCLUSION

These results suggested that suicidal BD exhibited increased dFC variability of hippocampal-temporal cortex and less HPA axis hyperactivity, which may affect their personality traits.

Gene expression alterations in the postmortem hippocampus from older patients with bipolar disorder - A hypothesis generating study

Bipolar disorder (BD) presents with a progressive course in a subset of patients. However, our knowledge of molecular changes in older BD is limited. In this study, we examined gene expression changes in the hippocampus of BD from the Biobank of Aging Studies to identify genes of interest that warrant further exploration. RNA was extracted from the hippocampus from 11 subjects with BD and 11 age and sex-matched controls. Gene expression data was generated using the SurePrint G3 Human Gene Expression v3 microarray. Rank feature selection was performed to identify a subset of features that can optimally differentiate BD and controls. Genes ranked in the top 0.1% with log₂ fold change >1.2 were identified as genes of interest. Average age of the subjects was 64 years old; duration of disease was 21 years and 82% were female. Twenty-five genes were identified, of which all but one was downregulated in BD. Of these, CNTNAP4, MAP4, SLC4A1, COBL, and NEURL4 had been associated with BD and other psychiatric conditions in previous studies. We believe our findings have identified promising targets to inform future studies aiming to understand the pathophysiology of BD in later life.

Association between olfactory dysfunction and mood disturbances with objective and subjective cognitive deficits in long-COVID

Background and purpose

The coronavirus disease 2019 (COVID-19) has been associated with olfactory dysfunction. The persistent symptoms of anosmia or hyposmia were associated in previous studies with the development of memory impairment and mood disturbances. We aimed to investigate the association between the chronicity of reported olfactory dysfunction and subjective and objective cognitive performance in long-COVID patients and to explore whether their emotional symptoms are related to their cognition.

Methods

One hundred twenty-eight long-COVID participants were recruited. Reported symptomatology, subjective memory complaints, anxiety and depression symptomatology, and trait-anxiety were assessed. Subjective memory complaints and mood disturbances were compared among groups of participants with olfactory dysfunction as an acute (AOD), persistent (POD), or nonexistent (NOD) symptom. Seventy-six of the volunteers also participated in a face-to-face session to assess their objective performance on tests of general cognitive function and verbal declarative memory. Objective cognitive performance and mood disturbances were compared among the AOD, POD, and NOD groups.

Results

The subjective memory complaints and the anxiety and depression symptoms were similar among the groups, but the score in general cognitive function was lower in the participants with symptoms of acute olfactory dysfunction than in those with no olfactory symptoms at any time. Participants' memory complaints were positively related to their emotional symptoms. The relationship between depressive symptomatology and memory complaints interacted with the olfactory dysfunction, as it only occurred in the participants without symptoms of olfactory dysfunction. Depressive symptomatology and acute olfactory symptoms were negatively associated with general cognitive function and delayed memory performance. The months elapsed from diagnosis to assessment also predicted delayed memory performance. Anxious symptomatology was negatively associated with the immediate ability to recall verbal information in participants who did not present olfactory dysfunction in the acute phase of the infection.

Conclusion

Olfactory dysfunction in the acute phase of the infection by COVID-19 is related to cognitive deficits in objective tests, and mood disturbances are associated with self-reported and objective memory. These findings may contribute to further understanding the neuropsychological and emotional aspects of long-COVID.

Genomic regulatory sequences in the pathogenesis of bipolar disorder

The lifetime prevalence of bipolar disorder is estimated to be about 2%. Epigenetics defines regulatory mechanisms that determine relatively stable patterns of gene expression by controlling all key steps, from DNA to messenger RNA to protein. This Mini Review highlights recent discoveries of modified epigenetic control resulting from genetic variants associated with bipolar disorder in genome-wide association studies. The revealed epigenetic abnormalities implicate gene transcription and post-transcriptional regulation. In the light of these discoveries, the Mini Review focuses on the genes PACS1, MCHR1, DCLK3, HAPLN4, LMAN2L, TMEM258, GNL3, LRRC57, CACNA1C, CACNA1D, and NOVA2 and their potential biological role in the pathogenesis of bipolar disorder. Molecular mechanisms under control of these genes do not translate into a unified picture and substantially more research is needed to fill the gaps in knowledge and to solve current limitations in prognosis and treatment of bipolar disorder. In conclusion, the genetic and functional studies confirm the complex nature of bipolar disorder and indicate future research directions to explore possible targeted treatment options, eventually working toward a personalized approach.

Montelukast induces beneficial behavioral outcomes and reduces inflammation in male and female rats

Background

Accumulative data links inflammation and immune dysregulation to the pathophysiology of mental disorders; little is known regarding leukotrienes’ (LTs) involvement in this process. Circumstantial evidence suggests that treatment with leukotriene modifying agents (LTMAs) such as montelukast (MTK) may induce adverse neuropsychiatric events. Further methodic evaluation is warranted.

Objective

This study aims to examine behavioral effects, as well as inflammatory mediator levels of chronic MTK treatment in male and female rats.

Methods

Depression-like phenotypes were induced by exposing male and female rats to a chronic unpredictable mild stress (CUMS) protocol for four weeks. Thereafter, rats were treated (intraperitoneally) once daily, for two weeks, with either vehicle (dimethyl sulfoxide 0.2 ml/rat) or 20 mg/kg MTK. Following treatment protocols, behavioral tests were conducted and brain regions were evaluated for inflammatory mediators including tumor necrosis factor (TNF)-α, interleukin (IL)-6 and prostaglandin (PG) E2.

Results

Overall, MTK did not invoke negative behavioral phenotypes (except for an aggression-inducing effect in males). Numerous positive behavioral outcomes were observed, including reduction in aggressive behavior in females and reduced manic/hyperactive-like behavior and increased sucrose consumption (suggestive of antidepressant-like effect) in males. Furthermore, in control males, MTK increased IL-6 levels in the hypothalamus and TNF-α in the frontal cortex, while in control females it generated a robust anti-inflammatory effect. In females that were subjected to CUMS, MTK caused a prominent reduction in TNF-α and IL-6 in brain regions, whereas in CUMS-subjected males its effects were inconsistent.

Conclusion

Contrary to prior postulations, MTK may be associated with select beneficial behavioral outcomes. Additionally, MTK differentially affects male vs. female rats in respect to brain inflammatory mediators, plausibly explaining the dissimilar behavioral phenotypes of sexes under MTK treatment.

Childhood Trauma, the HPA Axis and Psychiatric Illnesses: A Targeted Literature Synthesis

Studies of early life stress (ELS) demonstrate the long-lasting effects of acute and chronic stress on developmental trajectories. Such experiences can become biologically consolidated, creating individual vulnerability to psychological and psychiatric issues later in life. The hippocampus, amygdala, and the medial prefrontal cortex are all important limbic structures involved in the processes that undermine mental health. Hyperarousal of the sympathetic nervous system with sustained allostatic load along the Hypothalamic Pituitary Adrenal (HPA) axis and its connections has been theorized as the basis for adult psychopathology following early childhood trauma. In this review we synthesize current understandings and hypotheses concerning the neurobiological link between childhood trauma, the HPA axis, and adult psychiatric illness. We examine the mechanisms at play in the brain of the developing child and discuss how adverse environmental stimuli may become biologically incorporated into the structure and function of the adult brain via a discussion of the neurosequential model of development, sensitive periods and plasticity. The HPA connections and brain areas implicated in ELS and psychopathology are also explored. In a targeted review of HPA activation in mood and psychotic disorders, cortisol is generally elevated across mood and psychotic disorders. However, in bipolar disorder and psychosis patients with previous early life stress, blunted cortisol responses are found to awakening, psychological stressors and physiological manipulation compared to patients without previous early life stress. These attenuated responses occur in bipolar and psychosis patients on a background of increased cortisol turnover. Although cortisol measures are generally raised in depression, the evidence for a different HPA activation profile in those with early life stress is inconclusive. Further research is needed to explore the stress responses commonalities between bipolar disorder and psychosis in those patients with early life stress.

Resilience and young people's brain structure, function and connectivity: A systematic review

Although negative early life experiences are associated with an increased risk of developing psychopathology, some individuals exposed to childhood adversity demonstrate psychological resilience. Little is known about the neural correlates of resilience, especially in young people. To address this gap, we conducted a systematic review of neuroimaging studies of resilience in youth. The PubMed, Web of Science, Scopus, and PsycINFO databases were searched; 5,482 studies were identified. Following title/abstract screening, and full reading of the remaining articles, 22 studies based on 19 unique datasets were included. We found preliminary evidence that resilience is associated with structural, functional, and connectivity differences in young people, as assessed using structural and functional MRI and diffusion tensor imaging methods. Despite heterogeneity in definitions/assessment of resilience and a limited number of studies, the neuroimaging literature suggests some convergence across modalities regarding brain regions linked to resilience (especially the prefrontal cortex). Future studies would benefit from adopting longitudinal designs, broader conceptualisations of resilience that capture the impact of adversity exposure, and a dimensional approach to psychopathology.

Structural brain abnormalities associated with cognitive impairments in bipolar disorder

OBJECTIVE

Cognitive impairment has been highlighted as a core feature of bipolar disorder (BD) that often persists during remission. The specific brain correlates of cognitive impairment in BD remain unclear which impedes efficient therapeutic approaches. In a large sample of remitted BD patients, we investigated whether morphological brain abnormalities within dorsal prefrontal cortex (PFC) and hippocampus were related to cognitive deficits.

METHODS

Remitted BD patients (n = 153) and healthy controls (n = 52) underwent neuropsychological assessment and structural MRI. Based on hierarchical cluster analysis of neuropsychological test performance, patients were classified as either cognitively impaired (n = 91) or cognitively normal (n = 62). The neurocognitive subgroups were compared amongst each other and with healthy controls in terms of dorsal PFC cortical thickness and volume, hippocampus shape and volume, and total cerebral grey and white matter volumes.

RESULTS

Cognitively impaired patients displayed greater left dorsomedial prefrontal thickness compared to cognitively normal patients and healthy controls. Hippocampal grey matter volume and shape were similar across patient subgroups and healthy controls. At a whole-brain level, cognitively impaired patients had lower cerebral white matter volume compared to the other groups. Across all participants, lower white matter volume correlated with more impaired neuropsychological test performance.

CONCLUSIONS

Our findings associate cognitive impairment in bipolar disorder with cerebral white matter deficits, factors which may relate to the observed morphological changes in dorsomedial PFC possibly due to increased neurocognitive effort to maintain symptom stability in these remitted patients.

Norms for the Screen for Cognitive Impairment in Psychiatry and cognitive trajectories in bipolar disorder

BACKGROUND

The International Society for Bipolar Disorders Targeting Cognition Task Force recommends screening for and monitoring of cognitive impairments in patients with bipolar disorder (BD) with the Screen for Cognitive Impairment in Psychiatry (SCIP). The study aimed to provide the first demographically adjusted norms and change norms for the SCIP and to compare the cognitive trajectory over one year in remitted BD patients with normative cognitive change.

METHODS

Patients with fully or partially remitted BD and healthy controls (HC) were assessed with the SCIP at baseline and at a one-year follow-up. Regression-based models were used to determine demographically adjusted norms and change norms. Using the change models, predicted follow-up scores were calculated for BD and HC, and independent t-tests were used to compare deviations of the observed from the predicted follow-up scores for BD vs. HC to assess differences in cognitive trajectories.

RESULTS

Baseline data were collected for n=273 HC and n=218 BD, and follow-up data for n=139 HC and n=74 BD. Baseline norm models included age, sex and years of education, while change models included baseline SCIP scores and age. Patients with follow-up data showed selective impairments within verbal learning and recall at baseline. They followed the normative cognitive trajectories for all cognitive domains but verbal learning.

LIMITATIONS

Cognition was assessed with a screening tool.

CONCLUSIONS

We recommend implementing demographically adjusted norms and change norms for the SCIP in clinical and research settings. Change norms seem sensitive to subtle and selective cognitive decline over one year in remitted BD.

Using mitochondrial respiration inhibitors to design a novel model of bipolar disorder-like phenotype with construct, face and predictive validity

We mimicked mild mitochondrial-distress robustly reported in bipolar-disorder (BD) by chronic exposure to uniquely low doses of inhibitors of mitochondrial-respiration complexes in vitro and in vivo. Exposure of the neuronal-originating SH-SY5Y cells to very low dose (10 pM) rotenone, a mitochondrial-respiration complex (Co)I inhibitor, for 72 or 96 h did not affect cell viability and reactive oxygen species (ROS) levels. Yet, it induced a dual effect on mitochondrial-respiration: overshooting statistically significant several-fold increase of most oxygen-consumption-rate (OCR) parameters vs. significantly decreased all OCR parameters, respectively. Chronic low doses of 3-nitropropionic acid (3-NP) (CoII inhibitor) did not induce long-lasting changes in the cells' mitochondria-related parameters. Intraperitoneal administration of 0.75 mg/kg/day rotenone to male mice for 4 or 8 weeks did not affect spontaneous and motor activity, caused behaviors associated with mania and depression following 4 and 8 weeks, respectively, accompanied by relevant changes in mitochondrial basal OCR and in levels of mitochondrial-respiration proteins. Our model is among the very few BD-like animal models exhibiting construct (mild mitochondrial dysfunction), face (decreased/increased immobility time in the forced-swim test, increased/decreased consumption of sweet solution, increased/decreased time spent in the open arms of the elevated plus maze) and predictive (reversal of rotenone-induced behavioral changes by lithium treatment) validity. Our rotenone regime, employing doses that, to the best of our knowledge, have never been used before, differs from those inducing Parkinson's-like models by not affecting ROS-levels and cell-viability in vitro nor motor activity in vivo.

Doxycycline reverses cognitive impairment, neuroinflammation and oxidative imbalance induced by D-amphetamine mania model in mice: A promising drug repurposing for bipolar disorder treatment?

Immune-inflammatory mechanisms are involved in the pathophysiology of bipolar disorder. Tetracyclines present neuroprotective actions based on their anti-inflammatory and microglia suppressant effects. Doxycycline (DOXY) is a tetracycline that demonstrates a better usage profile with protective actions against inflammation and CNS injury. Here, we investigated the effects of DOXY against behavioral, neuroinflammatory, and pro-oxidative changes induced by the d-amphetamine mania model. Adult mice were given d-amphetamine 2.0 mg/kg or saline for 14 days. Between days 8 and 14, received lithium, DOXY (25 or 50 mg/kg), or their combination (lithium+DOXY) on both doses. We collected the brain areas prefrontal cortex (PFC), hippocampus, and amygdala to evaluate inflammatory and oxidative alterations. D-amphetamine induced hyperlocomotion and impairment in recognition and working memory. Lithium reversed hyperlocomotion but could not restore cognitive alterations. DOXY alone (at both doses) or combined with lithium reversed d-amphetamine-induced cognitive changes. DOXY, better than lithium, reversed the d-amphetamine-induced rise in TNFα, MPO, and lipid peroxidation. DOXY reduced the hippocampal expression of Iba1 (a marker of microglial activation), inducible nitric oxide synthase (iNOS), and nitrite. Combined with lithium, DOXY increased the phosphorylated (inactivated) form of GSK3β (Ser9). Therefore, DOXY alone or combined with lithium reversed cognitive impairment and neuroinflammation induced by the mice's d-amphetamine model. This study points to DOXY as a promising adjunctive tool for bipolar disorder treatment focused on cognition and neuroimmune changes. Our data provide the first rationale for clinical trials investigating DOXY therapeutic actions in bipolar disorder mania.

Comparison of cognitive dysfunction between schizophrenia and bipolar disorder patients: A meta-analysis of comparative studies

OBJECTIVE

Cognitive dysfunction is common in both schizophrenia and bipolar disorder. This is a meta-analysis of studies that compared cognitive dysfunction between schizophrenia and bipolar disorder.

METHODS

Both international and Chinese databases were systematically searched. Studies that compared cognitive function between schizophrenia and bipolar disorder with the MATRICS Consensus Cognitive Battery (MCCB) were analyzed using the random-effects model.

RESULTS

Twelve studies with 9,518 participants (4,411 schizophrenia and 5,107 bipolar patients) were included in the analyses. Schizophrenia patients performed significantly worse than bipolar patients on the MCCB total scores with a large effect size (SMD=-0.80, 95%CI: -1.21 to -0.39), as well as on all the 7 subscale scores; attention (SMD=-2.56, 95%CI: -3.55 to -1.57) and social cognition (SMD=-0.86, 95%CI: -1.13 to -0.58) with large effect sizes; and speed of processing (SMD=-0.75, 95%CI: -1.00 to -0.49), working memory (SMD=-0.68, 95%CI: -0.91 to -0.45), verbal learning (SMD=-0.78, 95%CI: -0.95 to -0.61), visual learning (SMD=-0.65, 95%CI: -0.83 to -0.48), and reasoning and problem solving (SMD=-0.61, 95%CI: -0.93 to -0.29) with medium effect sizes.

CONCLUSION

Compared to bipolar patients, patients with schizophrenia had more severe cognitive dysfunction in this meta-analysis, particularly in attention and social cognition. Timely assessment and treatment of cognitive dysfunction should be part of standard management protocols in both schizophrenia and bipolar disorder.

Alterations of Spontaneous Brain Activity in Hemodialysis Patients

Cognitive impairment is prevalent in hemodialysis end-stage renal disease (ESRD) patients. It might be associated with poor prognosis. Nevertheless, the underlying mechanisms have not been completely clarified. This study explored spontaneous brain activity in ESRD patients on hemodialysis by using the amplitude of low-frequency fluctuation (ALFF). Nineteen ESRD patients on regular hemodialysis were included in this study. Eighteen age-, sex- and education level-matched volunteers were enrolled as the healthy control group. All participants had resting-state functional MRI scanning, neuropsychological tests, and laboratory testing. ALFF was used for assessing intrinsic brain activity. Independent samples t-test was used for obtaining group differences. Spearman correlation analysis was applied to assess the association between ALFF changes, neuropsychological, and clinical indices. Compared to the healthy control group, hemodialysis patients showed decreased ALFF in the precuneus, right angular gyrus/inferior lobule as well as increased ALFF in the left parahippocampus/hippocampus and right precentral/postcentral gyrus. The ALFF abnormalities in these regions were closely associated with hemoglobin levels. Also, increased ALFF in the left parahippocampus/hippocampus showed a negative correlation with the score of long-delayed free recall. Hemodialysis patients had aberrant ALFF in the default mode network (DMN) regions, particularly in the precuneus and parahippocampus/hippocampus, which may be correlated with neuropathological mechanisms involved in hemodialysis.

Neurocan genome-wide psychiatric risk variant affects explicit memory performance and hippocampal function in healthy humans

Alterations of the brain extracellular matrix (ECM) can perturb the structure and function of brain networks like the hippocampus, a key region in human memory that is commonly affected in psychiatric disorders. Here, we investigated the potential effects of a genome-wide psychiatric risk variant in the NCAN gene encoding the ECM proteoglycan neurocan (rs1064395) on memory performance, hippocampal function and cortical morphology in young, healthy volunteers. We assessed verbal memory performance in two cohorts (N = 572, 302) and found reduced recall performance in risk allele (A) carriers across both cohorts. In 117 participants, we performed functional magnetic resonance imaging using a novelty-encoding task with visual scenes. Risk allele carriers showed higher false alarm rates during recognition, accompanied by inefficiently increased left hippocampal activation. To assess effects of rs1064395 on brain morphology, we performed voxel-based morphometry in 420 participants from four independent cohorts and found lower grey matter density in the ventrolateral and rostral prefrontal cortex of risk allele carriers. In silico eQTL analysis revealed that rs1064395 SNP is linked not only to increased prefrontal expression of the NCAN gene itself, but also of the neighbouring HAPLN4 gene, suggesting a more complex effect of the SNP on ECM composition. Our results suggest that the NCAN rs1064395 A allele is associated with lower hippocampus-dependent memory function, variation of prefrontal cortex structure and ECM composition. Considering the well-documented hippocampal and prefrontal dysfunction in bipolar disorder and schizophrenia, our results may reflect an intermediate phenotype by which NCAN rs1064395 contributes to disease risk.

Gray matter voxel-based morphometry in mania and remission states of children with bipolar disorder

BACKGROUND

It has been found by many studies that gray matter (GM) abnormalities exist in both adults and children with bipolar disorder (PBD) which is a serious mental illness characterized by alternating episodes of mania and depression. However, there are few studies on the comparison between brain imaging of different mood states shown by patients with bipolar disorder. This study is aimed at exploring the differences existing in brain structures between children with bipolar disorder and that of healthy controls, and then it tries to further explore whether there is a structural difference between the states of mania and remission in children with bipolar disorder.

METHODS

21 PBD-mania subjects, 19 PBD-remission subjects and 18 control subjects aged 12-17 years old were engaged in this study. In the present study, magnetic resonance imaging was obtained by employing a Siemens 3.0 T scanner. With regard to the volumes of gray matter in the mania group, remission group and healthy control group, analysis was carried out by using voxel-based morphometry (VBM). Further analysis was conducted on the correlation between MRI data and clinical features of patients with PBD.

RESULTS

In comparison with the healthy control subjects, the gray matter volume measured from the left hippocampus, parahippocampal gyrus and amygdala in both manic and euthymic groups showed a decreasing trend, while the volume of left orbitofrontal cortex increased. However, no significant difference in volumes was found between BD manic and euthymic groups. It was observed that the volume of orbitofrontal cortex had a positive correlation with onset age in PBD euthymic group.

CONCLUSIONS

Our study came to the conclusion that extensive brain structural changes are available in patients with PBD. The brain regions with structural changes are distributed in the anterior limbic network (ALN), which has been proved to have been involved in the abnormal emotional and cognitive regulation of PBD. However, there is no difference in the volumes of gray matter between mania and remission in PBD .

Insulin resistance is associated with verbal memory impairment in bipolar disorders

BACKGROUND

Cognitive impairment contributes to deterioration in social, family and work functioning in Bipolar Disorder (BD). Cognitive deficits are present not only during, but also outside of mood episodes. Insulin resistance (IR) impairs cognitive functioning and is frequent in participants with BD. Thus, we hypothesized that IR might contribute to cognitive deficits in remitted BD participants.

METHODS

We acquired biochemical (fasting insulin, glucose, lipids) cognitive (California Verbal Learning Test, Digit Span) measures from 100 euthymic participants with BD type I or II. IR was diagnosed using HOMA-IR.

RESULTS

BD participants with IR displayed worse composite verbal memory score (-0.38 vs 0.17; F(1, 8.23)=17.90; p = 0.003), while composite working memory scores were comparable in patients with or without IR (-0.20 vs 0.07; F(1, 6.05)=1.64; p = 0.25). Insulin resistance remained significantly associated with composite verbal memory scores (F(1, 47.99)=9.82, p = 0.003) even when we controlled for levels of lipids. The association between IR and verbal memory was not confounded by exposure to antipsychotics, which were not associated with worse cognitive performance (F(1, 2.07)=5.95, p = 0.13).

LIMITATIONS

The main limitation is the cross-sectional design, which does not allow us to rule out reverse causation.

CONCLUSIONS

We demonstrated that among remitted BD participants without diabetes mellitus, IR was significantly associated with verbal memory performance, even when we controlled for other relevant metabolic or treatment variables. These findings raise the possibility that early detection and treatment of IR, which is reversible, could possibly improve cognitive functioning in at least some BD participants.

Neuroinflammation in Bipolar Depression

Bipolar disorder (BD) is a leading cause of worldwide disability among mood disorders. Pathological mechanisms are still vastly unclear, and current treatments with conventional medications are often unsatisfactory in maintaining symptoms control and an adequate quality of life. Consequently, current research is focusing on shedding new light on disease pathogenesis, to improve therapeutic effectiveness. Recent evidence has suggested a prominent role of inflammation in mood disorders. Elevated levels of peripheral proinflammatory mediators have been reported in BD, as well as in other mood disorders, and people with systemic autoimmune diseases have an increased risk of developing BD. These immunological alterations are stable, and current medications are unable to alter peripheral concentrations even when clinical improvement is evident. These findings have also been replicated in the central nervous system (CNS) milieu, whereas genetic studies have shown that these immune alterations are not due to the disorder itself, being detectable before the illness onset. Moreover, these inflammatory modifications seem to be affected by and linked to other biomarkers of the disorder, such as alterations of white matter (WM) microstructure, metabolism, kynurenine pathway, and circadian rhythmicity. Finally, these immune variations seem to be useful as predictors of therapeutic responsiveness to medications, and in discriminating between clinically different outcomes. The objective of this review is to summarize available evidence on the connection between inflammation and BD, focusing on peripheral inflammatory markers and recent findings on their connection with other typical features of BD, to outline a general overview of the disorder. Moreover, it is meant to analyze the issues with data gathering and interpretation, given the partially contradictory and inconsistent nature of results.

Improvement in verbal learning over the first year of antipsychotic treatment is associated with serum HDL levels in a cohort of first episode psychosis patients

To investigate whether changes in serum lipids are associated with cognitive performance in first episode psychosis (FEP) patients during their first year of antipsychotic drug treatment. One hundred and thirty-two antipsychotic-treated FEP patients were included through the TOP study along with 83 age- and gender-matched healthy controls (HC). Information regarding cognitive performance, psychotic symptoms, lifestyle, body mass index, serum lipids [total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein cholesterol, and triglycerides] and antipsychotic treatment was obtained at baseline and after 1 year. The cognitive test battery is comprised of assessments for verbal learning, processing speed, working memory, verbal fluency, and inhibition. Mixed-effects models were used to study the relationship between changes over time in serum lipids and cognitive domains, controlling for potential confounders. There was a significant group by HDL interaction effect for verbal learning (F = 11.12, p = 0.001), where an increase in HDL levels was associated with improvement in verbal learning in FEP patients but not in HC. Practice effects, lifestyle, and psychotic symptoms did not significantly affect this relationship. Antipsychotic-treated FEP patients who increased in HDL levels during the first year of follow-up exhibited better verbal learning capacity. Further investigations are needed to clarify the underlying mechanisms.

Structural changes in the hippocampus as a biomarker for cognitive improvements in neuropsychiatric disorders: A systematic review

Cognitive impairments are a core feature of several neuropsychiatric disorders. A common biomarker for pro-cognitive effects may provide a much-needed tool to select amongst candidate treatments targeting cognition. The hippocampus is a promising biomarker for target-engagement due to the illness-associated morphological hippocampal changes across unipolar disorder (UD), bipolar disorder (BD) and schizophrenia (SCZ). Following the PRISMA guidelines, we searched PubMed and Embase, for clinical trials targeting cognition across neuropsychiatric disorders, with longitudinal structural magnetic resonance imaging (MRI) measures of the hippocampus. Five randomized and three open-label trials were included. Hippocampal volume increases were associated with treatment-related cognitive improvement following treatment with erythropoietin across UD, BD and SCZ, lithium treatment in BD and aerobic exercise in SCZ. Conversely, an exercise intervention in UD showed no effect on hippocampal volume or cognition. Together, these observations point to hippocampal volume change as a putative biomarker-model for cognitive improvement. Future cognition trials are encouraged to include MRI assessments pre- and post-treatment to assess the validity of hippocampal changes as a biomarker for pro-cognitive effects.

Hippocampal subfield volumes in major depressive disorder and bipolar disorder

BACKGROUND

The hippocampus is not a uniform structure, but rather consists of multiple, functionally specialized subfields. Few studies have explored hippocampal subfield volume difference in the same sample of major depressive disorder (MDD) and bipolar disorder (BD) cases. We aimed to investigate the difference of hippocampal subfield volume between patents with MDD and BD and healthy controls (HCs).

METHODS

A total of 102 MDD and 55 BD patients and 135 HCs were recruited and underwent T1-weighted image. Hippocampal subfield volume was calculated by automated segmentation and volumetric procedures developed by Iglesias et al. and implemented in FreeSurfer. Volume differences between the groups were analyzed using the analysis of covariance and controlling for age, sex, and total intracranial cavity volume.

RESULTS

Patients with MDD had significantly reduced volumes in the bilateral cornu ammonis 1 (CA1), CA4, the granule cell layer (GCL), molecular layer (ML), whole hippocampus, the left CA2/3, and right presubiclum and subiculum. Patients with BD had significantly reduced volumes in the right CA1, GCL, and the whole hippocampus as compared to HCs. No significant volume differences were observed between the MDD and BD groups. Illness duration was negatively correlated with volumes of the left CA1, CA4, ML, presubiculum, subiculum, and the whole hippocampus in patients with BD.

CONCLUSION

We observed hippocampal subfield volume reductions in both MDD and BD, a finding which more prominent in MDD. The inverse correlation between BD illness duration and hippocampal subfield volume may evidence the neuroprogressive nature of BD.

Patients With Drug-Naive Bipolar Disorder in Remission After 8 Weeks of Treatment Had Decreased Serum Uric Acid Concentrations

Background: Evidence indicates that the serum concentration of uric acid (UA) in patients may relate both to the pathophysiology and therapeutics of bipolar disorder (BPD). The purpose of this study was to examine the changes and clinical significance of serum UA concentrations in first-episode manic patients suffering from BPD. Methods: Seventy-six drug-naive patients with first-episode bipolar mania and 76 age- and gender-matched healthy subjects were recruited. Young Mania Rating Scale and Hamilton Depression Rating Scale were used to assess clinical symptoms. We tested serum UA concentrations by sandwich enzyme-linked immunosorbent assay at baseline and at the end of 8-week treatment in BPD patients and in the control group. Results: After 8-week quetiapine and sodium valproate treatment, this study revealed that the serum UA concentrations in remitted patients were significantly lower than nonremitted patients; however, those remitted patients still had higher serum UA than healthy controls. We discovered that the baseline UA concentration was higher in nonremitted than remitted patients after 8 weeks of treatment. Finally, a positive association was found between serum UA and symptom relief in the first episode of manic disorder patients. Conclusion: Patients with first-episode BPD had high levels of serum UA, which responds to treatment mainly in remitted patients. Our results suggest that serum UA concentrations might present potentially a trait marker in bipolar patients.

Sex-related variation of neurocognitive functioning in bipolar disorder: Focus on visual memory and associative learning

Bipolar disorder (BD) is associated with cognitive deficits in attention, verbal memory and executive functions. However, only few studies have examined sex effects on cognition despite their clinical relevance. Given that visual memory/ learning has been understudied the aim of our study was to investigate sex-related variation in cognition (executive functions and visual memory/ learning) in BD. Cognitive performance of 60 bipolar-I patients and 30 healthy controls was evaluated by using CANTAB battery tasks targeting spatial memory (SRM), paired associative learning (PAL) and executive functions. We fitted a multivariate analysis of covariance (MANCOVA), followed by task-specific ANCOVAs. A significant diagnosis by sex interaction effect was detected (MANCOVA); specifically, diagnosis-specific sex effects were found for SRM and PAL, as healthy males outperformed healthy females but this pattern was attenuated in BD patients. Patients' clinicodemographic characteristics, current psychopathology or medication status did not differ across sexes and were, therefore, unlikely to explain detected sex effects. Our study is one of few studies to assess sex-related variation in cognition in BD and the first to record a diagnosis-specific sex effect for two tasks of visuo-spatial memory/ learning, indicating that sex-related variation in healthy subjects is disrupted in BD.

Sex differences of hippocampal structure in bipolar disorder

Although differential patterns in clinical characteristics have been consistently noted between male and female patients with bipolar disorder (BD), the effect of sex on the hippocampal structure remains unclear. To address this, the present study investigated the effects of BD and sex on the hippocampal structure, and the relationship between the hippocampal structure and cognitive performance. Morphometric and neurocognitive analyses were performed in 91 subjects (patients with BD: male/female = 33/19; normal controls: male/female = 22/17). Patients had significantly decreased left parahippocampal gyrus area and left/right hippocampal volume compared to normal controls. Within the BD group only, female patients presented with smaller right hippocampal volume than males. In the Spatial Span (SS) test (used to assess working memory capacity) and the Maze test (used to evaluate the ability to anticipate), patients demonstrated decreased performance compared to normal controls, with a significant main effect of sex. Left parahippocampal gyrus area and right hippocampal volume were positively correlated with SS and Maze in patients; moreover, right hippocampal volume predicted 17.4% of SS performance variance. These results suggest that there may be a difference between male and female patients with regard to right hippocampal volume, and that female patients may need more attention than males.

Clinical and treatment-related predictors of cognition in bipolar disorder: focus on visual paired associative learning

Bipolar disorder (BD) is associated with impairment in cognitive domains such as verbal memory and executive functions. However, visual paired associative learning (PAL) has been far less researched. Neurocognitive dysfunction in BD patients has been related to several clinical factors, but data on the effect of medication are relatively scarce and inconsistent. The aim of our study was to explore the effect of clinical and treatment-related parameters on executive functions and visual memory/learning, including PAL, in BD. Cognitive performance of 60 bipolar I patients and 30 healthy subjects was evaluated by using CANTAB battery tasks targeting spatial recognition memory, PAL and executive functions (set shifting, planning, inhibitory control). Bipolar patients showed poorer performance in PAL, set shifting, planning and inhibitory control than healthy subjects; however, only differences in PAL and planning survived correction for multiple comparisons. Number of previous manic episodes and illness duration predicted worse performance in set shifting and PAL, respectively, whereas current treatment with valproate predicted better performance in PAL. This is one of the first studies to assess clinical and treatment-related predictors of PAL in BD. We report a possibly beneficial effect of valproate on PAL, which warrants further investigation.

Hippocampal volume changes following electroconvulsive therapy: a systematic review and meta-analysis

INTRODUCTION

Reduced hippocampal volume is one of the most consistent morphological findings in Major Depressive Disorder (MDD). Electroconvulsive therapy (ECT) is the most effective therapy for MDD, yet its mechanism of action remains poorly understood. Animal models show that ECT induces several neuroplastic processes, which lead to hippocampal volume increases. We conducted a meta-analysis of ECT studies in humans to investigate its effects on hippocampal volume.

METHODS

PubMed was searched for studies examining hippocampal volume before and after ECT. A random-effects model was used for meta-analysis with standardized mean difference (SMD) of the change in hippocampal volume before and after ECT as the primary outcome. Nine studies involving 174 participants were included.

RESULTS

Total hippocampal volumes increased significantly following ECT compared to pre-treatment values (SMD=1.10; 95% CI 0.80-1.39; z=7.34; p<0.001; k=9). Both right (SMD=1.01; 95% CI 0.72-1.30; z=6.76; p<0.001; k=7) and left (SMD=0.87; 95% CI 0.51-1.23; z=4.69; p<0.001; k=7) hippocampal volumes were also similarly increased significantly following ECT. We demonstrated no correlation between improvement in depression symptoms with ECT and change in total hippocampal volume (beta=-1.28, 95% CI -4.51-1.95, z=-0.78, p=0.44).

CONCLUSION

We demonstrate fairly consistent increases in hippocampal volume bilaterally following ECT treatment. The relationship among these volumetric changes and clinical improvement and cognitive side effects of ECT should be explored by larger, multisite studies with harmonized imaging methods.

Consistently altered expression of gene sets in postmortem brains of individuals with major psychiatric disorders

The measurement of gene expression in postmortem brain is an important tool for understanding the pathogenesis of serious psychiatric disorders. We hypothesized that major molecular deficits associated with psychiatric disease would affect the entire brain, and such deficits may be shared across disorders. We performed RNA sequencing and quantified gene expression in the hippocampus of 100 brains in the Stanley Array Collection followed by replication in the orbitofrontal cortex of 57 brains in the Stanley Neuropathology Consortium. We then identified genes and canonical pathway gene sets with significantly altered expression in schizophrenia and bipolar disorder in the hippocampus and in schizophrenia, bipolar disorder and major depression in the orbitofrontal cortex. Although expression of individual genes varied, gene sets were significantly enriched in both of the brain regions, and many of these were consistent across diagnostic groups. Further examination of core gene sets with consistently increased or decreased expression in both of the brain regions and across target disorders revealed that ribosomal genes are overexpressed while genes involved in neuronal processes, GABAergic signaling, endocytosis and antigen processing have predominantly decreased expression in affected individuals compared to controls without a psychiatric disorder. Our results highlight pathways of central importance to psychiatric health and emphasize messenger RNA processing and protein synthesis as potential therapeutic targets for all three of the disorders.

Association between cytokine levels, verbal memory and hippocampus volume in psychotic disorders and healthy controls

OBJECTIVE

We investigated whether elevated plasma levels of immune markers were associated with verbal memory and hippocampal subfield volumes in patients with severe mental illnesses and in healthy controls.

METHOD

In total, 230 patients with a broad DSM-IV schizophrenia spectrum illness or bipolar disorder and 236 healthy controls were recruited. Memory was assessed using the Wechsler Memory Scale-Third Edition (WMS-III) Logical Memory immediate and delayed recall, and the California Verbal Learning Test summed recall over learning list (CVLT learning) and delayed free recall. We measured plasma levels of soluble tumor necrosis factor receptor 1 (sTNF-R1), interleukin-1 receptor antagonist, interleukin-6, von Willebrand factor, osteoprotegerin, high-sensitivity C-reactive protein and sCD40 ligand. Hippocampal subfield estimates were obtained using FreeSurfer.

RESULTS

We found a moderate negative association between sTNF-R1 and performance on verbal memory learning and recall tests as measured by the WMS-III Logical Memory after controlling for age, sex and diagnosis. We observed no interaction effect of diagnosis and sTNF-R1 on memory scores. We also found a nominally significant positive association between CVLT learning and hippocampal volumes.

CONCLUSION

The findings suggest a role for immune involvement in memory independent of severe mental disorders and may support the 'bigger is better' hypothesis of hippocampal subfield volumes.

Verbal memory impairment in new onset bipolar disorder: Relationship with frontal and medial temporal morphology

OBJECTIVES

Verbal memory (VM) impairment is a trait feature of bipolar I disorder (BDI) that is present at illness onset and associated with functional outcome. However, little is known about the morphological abnormalities underlying this deficit early in the disease course. This study examined the neurobiological correlates of VM impairment in euthymic newly diagnosed patients, with attention to frontal and medial temporal (MT) structures known to contribute to VM.

METHODS

Euthymic patients with BDI recently recovered from their first episode of mania (n = 42) were compared with healthy subjects (n = 37) using measures of the California Verbal Learning Test (CVLT-II) associated with frontal and MT functioning. A subset of participants had 3T MRI scan (n = 31 patient group, n = 30 healthy subject group). Hippocampal and prefrontal volumes were analyzed using FreeSurfer 5.1 and correlated with their corresponding CVLT-II subscores.

RESULTS

Patients showed decreased performance in total learning as well as short and long delay verbal recall. Consistent with MT dysfunction, they also showed deficits in recognition discriminability and learning slope. In the patient group only, left hippocampal volumes were negatively correlated with these measures.

CONCLUSIONS

These results suggest that anomalous MT functioning is involved with VM impairment early in the course of BDI.

Hippocampal structure and function in individuals with bipolar disorder: a systematic review

INTRODUCTION

Bipolar disorder (BD) is a psychiatric disorder accompanied by deficits in declarative memory. Given the importance of the hippocampus in declarative memory, it is not surprising that BD patients have been reported to show hippocampal abnormalities.

OBJECTIVES

Review evidence about structural and functional hippocampal abnormalities in BD.

METHODS

Systematic review of studies comparing BD patients and healthy controls with respect to hippocampal structure or function.

RESULTS

Twenty-five studies were included, together involving 1043 patients, 21 of which compared patients to controls. Decrease in hippocampal volume was found in four of 18 studies using adult samples, and two of three samples using adolescents. Four studies revealed localized hippocampal deficits. Meta-analysis revealed a significant but small effect with lower hippocampal volumes when comparing all BD patients with controls. Lithium treatment was associated with larger hippocampal volumes across studies. The three functional studies yielded contradictory evidence.

LIMITATIONS

Studies were only cross-sectional in nature and all used MRI or fMRI to investigate hippocampal volume or function. Heterogeneous patients groups and different methodologies for hippocampal segmentation, may have contributed to difficulties when comparing the different studies.

CONCLUSIONS

There seems to be a small reduction in hippocampal volume in BD, which perhaps is more pronounced in early-onset BD and is counteracted by a neuroprotective effect of lithium treatment. However, how these structural abnormalities relate to functional deficits is largely unclear. Given the few functional neuroimaging studies and given the lack of congruence in these results, further investigation of especially hippocampal function in BD is recommended.

Prophylactic lithium treatment and cognitive performance in patients with a long history of bipolar illness: no simple answers in complex disease-treatment interplay

Cognitive impairment in patients with bipolar disorder (BD) is not restricted to symptomatic phases. It is also present in euthymia. There is evidence of differences in the brain's structure between bipolar patients and healthy individuals, as well as changes over time in patients. Lithium constitutes the gold standard in long-term prophylactic treatment. Appropriate therapy that prevents new episodes improves the disease's course and reduces the frequency of harmful outcomes. Interestingly, preclinical data suggest that lithium has a (additional) neuroprotective effect. There is limited data on its related effects in humans and even less on its long-term application. In this multi-center cross-sectional study from the International Group for the Study of Lithium-treated Patients (IGSLi), we compared three groups: bipolar patients without long-term lithium treatment (non-Li group; <3 months cumulative lithium exposure, ≥24 months ago), bipolar patients with long-term lithium treatment (Li group, ongoing treatment ≥24 months), and healthy subjects (controls). Strict inclusion and exclusion criteria were defined; the inclusion criteria for patients were diagnosis of BD types I or II, duration of illness ≥10 years, ≥5 episodes in patient's history and a euthymic mood state. Neurocognitive functioning was assessed using the Wechsler Adult Intelligence Scale-Revised (WAIS-R), the California Verbal Learning Test (CVLT), and a visual backward masking (VBM) task. A total of 142 subjects were included, 31 in the non-Li and 58 in the Li group, as well as 53 healthy controls. Treated patients with long-standing BD and controls did not differ significantly in overall cognitive functioning and verbal learning, recall, and recognition; regardless of whether lithium had been part of the treatment. Patients, however, demonstrated poorer early visual information processing than healthy controls, with the lithium-treated patients performing worse than those without. Our data suggest that bipolar patients with a long illness history and effective prophylactic treatment do not reveal significantly impaired general cognitive functioning or verbal learning and memory. However, they are worse at processing early visual information. Accompanying volumetric and spectroscopic data suggest cell loss in patients not treated with lithium that may be counterbalanced by long-term lithium treatment.

Impact of depressive episodes on cognitive deficits in early bipolar disorder: data from the Systematic Treatment Optimization Programme for Early Mania (STOP-EM)

BACKGROUND

Although manic episodes reportedly contribute to cognitive deficits in bipolar I disorder, the contribution of depressive episodes is poorly researched.

AIMS

We investigated the impact of depressive episodes on cognitive function early in the course of bipolar I disorder.

METHOD

A total of 68 patients and 38 controls from the Systematic Treatment Optimization Programme for Early Mania (STOP-EM) first-episode mania programme were examined. We conducted (a) a cross-sectional analysis of the impact of prior depressive episodes on baseline cognitive function and (b) a prospective analysis assessing the contribution of depression recurrence within 1 year following a first episode of mania on cognitive functioning.

RESULTS

The cross-sectional analysis showed no significant differences between patients with past depressive episodes compared with those without, on overall or individual domains of cognitive function (all P>0.09). The prospective analysis failed to reveal a significant group×time interaction for cognitive decline from baseline to 1 year (P = 0.99) in patients with a recurrence of depressive episodes compared with those with no recurrence. However, impaired verbal memory at baseline was associated with a depression recurrence within 1 year.

CONCLUSIONS

Although deficits in all domains of cognitive function are seen in patients early in the course of bipolar disorder, depressive episodes do not confer additional burden on cognitive function. However, poorer verbal memory may serve as a marker for increased susceptibility to depression recurrence early in the course of illness.

Hippocampal and orbital inferior frontal gray matter volume abnormalities and cognitive deficit in treatment-naive, first-episode patients with schizophrenia

BACKGROUND

Cognitive impairment is a core feature of schizophrenia. Some evidence suggests an association between cognition deficits and gray matter reductions. In this study, we investigated the relationship between cognitive performance and gray matter volumes in patients with treatment-naïve, first-episode schizophrenia.

METHOD

First-episode patients with treatment-naïve schizophrenia and healthy controls went through brain imaging scan using high resolution magnetic resonance imaging. A neuropsychological battery including 8 neurocognitive tests was used to assess cognitive function. Voxel-based methods were used for volumetric measure in the brain.

RESULTS

Fifty-one patients and 41 healthy controls were included in the analysis. Patients exhibited a poorer performance on all 7 cognitive function tests compared with healthy controls (ps<0.006). There were significant gray matter volume differences between the two groups in bilateral hippocampus gyri, right superior temporal gyrus, left fusiform gyrus and orbital inferior frontal gyri (FDR, ps<0.05). Within the schizophrenia group, multiple regression analysis demonstrated that poorer performance on the working memory, verbal learning and visual learning was associated with smaller hippocampal gray matter volume, and poorer executive function was associated with smaller left orbital inferior frontal gray matter volume after controlling for potential confounding variables (β ≥ 0.420, ps ≤ 0.010).

CONCLUSIONS

Our findings suggest that cognitive deficits are associated with hippocampal and orbital inferior frontal gray matter volume abnormalities in treatment-naïve, first-episode patients with schizophrenia.

Cytomegalovirus seropositivity and serointensity are associated with hippocampal volume and verbal memory in schizophrenia and bipolar disorder

INTRODUCTION

Cytomegalovirus (CMV) is a member of the herpesviridae family that has a limbic and temporal gray matter tropism. It is usually latent in humans but has been associated with schizophrenia, bipolar disorder and cognitive deficits in some populations. Hippocampal decreased volume and dysfunction play a critical role in these cognitive deficits. We hypothesized that CMV seropositivity and serointensity would be associated with hippocampal volume and cognitive functioning in patients with schizophrenia or bipolar disorder.

METHODS

102 healthy controls, 118 patients with bipolar disorder and 69 patients with schizophrenia performed the California Verbal Learning Test (CVLT) and had blood samples drawn to assess CMV IgG levels. A subgroup of 52 healthy controls, 31 patients with bipolar disorder and 27 patients with schizophrenia underwent T1 MRI for hippocampal volumetry. We analyzed the association between CMV serointensity and seropositivity with hippocampal volume. We also explored the correlation between CMV serointensity and seropositivity and CVLT scores.

RESULTS

In both patient groups but not in controls, higher CMV serointensity was significantly associated with smaller right hippocampal volume. Further, in the group of patients with schizophrenia but not bipolar disorder, CMV serointensity was negatively correlated with CVLT scores.

CONCLUSION

CMV IgG titers are associated with decreased hippocampal volume and poorer episodic verbal memory in patients with schizophrenia or bipolar disorder. The mechanism of this association warrants further exploration.

The spectrum of borderline personality disorder: a neurophysiological view

Borderline Personality Disorder (BPD) has been defined as a personality disorder in all editions of DSM since 1980; namely, DSM III through V. The criteria are a mixture of symptoms and traits; the etiology, a heterogeneous array of genetic, constitutional, and environmental factors. Until recently the diagnosis relied on clinical descriptions. In the last two decades, neurophysiological data, including MRI and fMRI, have established correlates in various brain regions, particularly those involving the frontal lobes and various limbic structures, that show promise of providing a more substantial basis for diagnosis-relying primarily on (internal) brain changes, rather than on (external) clinical observation. Some of the changes in BPD consist of decreased volume in the orbitofrontal and dorsolateral prefrontal cortices and smaller volume in both the amygdala and hippocampus, though with heightened reactivity in the amygdala. Similar abnormalities have been noted in bipolar disorders (BDs) and in ADHD, both of which often accompany BPD and share certain clinical features. Persons with strong genetic predisposition to BDs can develop BPD even in the absence of adverse environmental factors; those with extreme adverse environmental factors (chiefly, early sexual molestation) can develop BPD in the absence of bipolar vulnerability. In some BPD patients, both sets of factors are present. As ideal treatment depends on careful analysis of these factors, neurophysiological testing may permit both more rational, brain-based diagnostic decisions and more appropriate therapeutic strategies.

Combined analyses of gray matter voxel-based morphometry and white matter tract-based spatial statistics in pediatric bipolar mania

BACKGROUND

Ample evidence has suggested the presence of gray matter (GM) and white matter (WM) abnormalities in bipolar disorder (BD) patients, including pediatric bipolar disorder (PBD). However, little research has been done in PBD patients that carefully classify the mood states. The aim of the present study is to investigate the brain structural changes in PBD-mania children and adolescents.

METHODS

Eighteen children and adolescents with bipolar mania (male/female, 6/12) aged 10-18 years old and 18 age- and sex-matched healthy controls were included in the present study. The 3D T1-weighted magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) data were obtained on a Siemens 3.0 T scanner. Voxel-based morphometry (VBM) analysis and tract-based spatial statistics (TBSS) analysis were conducted to compare the gray matter volume and white matter fractional anisotropy (FA) value between patients and controls. Correlations of the MRI data of each survived area with clinical characteristics in PBD patients were further analyzed.

RESULTS

As compared with the control group, PBD-mania children showed decreased gray matter volume in the left hippocampus. Meanwhile, significant lower FA value was detected in the right anterior cingulate (AC) in the patient group. No region of increased gray matter volume or FA value was observed in PBD-mania. The hippocampal volume was negatively associated with the Young Mania Rating Scale (YMRS) score when controlling for clinical characteristics in PBD-mania patients, however, there was no significant correlation of FA value of the survived area with illness duration, the onset age, number of episodes, or the YMRS score in PBD-mania patients.

LIMITATION

The present outcomes require replication in larger samples and verification in medication free subjects.

CONCLUSIONS

Our findings highlighted that extensive brain structural lesions (including GM and WM) were existed in PBD-mania. The widespread occurrence of structural abnormalities mainly located in the anterior limbic network (ALN) which suggested that this network might contribute to emotional and cognitive dysregulations in PBD.

Potential mechanisms of action of lithium in bipolar disorder. Current understanding

Lithium has been used for over half a century for the treatment of bipolar disorder as the archetypal mood stabilizer, and has a wealth of empirical evidence supporting its efficacy in this role. Despite this, the specific mechanisms by which lithium exerts its mood-stabilizing effects are not well understood. Given the inherently complex nature of the pathophysiology of bipolar disorder, this paper aims to capture what is known about the actions of lithium ranging from macroscopic changes in mood, cognition and brain structure, to its effects at the microscopic level on neurotransmission and intracellular and molecular pathways. A comprehensive literature search of databases including MEDLINE, EMBASE and PsycINFO was conducted using relevant keywords and the findings from the literature were then reviewed and synthesized. Numerous studies report that lithium is effective in the treatment of acute mania and for the long-term maintenance of mood and prophylaxis; in comparison, evidence for its efficacy in depression is modest. However, lithium possesses unique anti-suicidal properties that set it apart from other agents. With respect to cognition, studies suggest that lithium may reduce cognitive decline in patients; however, these findings require further investigation using both neuropsychological and functional neuroimaging probes. Interestingly, lithium appears to preserve or increase the volume of brain structures involved in emotional regulation such as the prefrontal cortex, hippocampus and amygdala, possibly reflecting its neuroprotective effects. At a neuronal level, lithium reduces excitatory (dopamine and glutamate) but increases inhibitory (GABA) neurotransmission; however, these broad effects are underpinned by complex neurotransmitter systems that strive to achieve homeostasis by way of compensatory changes. For example, at an intracellular and molecular level, lithium targets second-messenger systems that further modulate neurotransmission. For instance, the effects of lithium on the adenyl cyclase and phospho-inositide pathways, as well as protein kinase C, may serve to dampen excessive excitatory neurotransmission. In addition to these many putative mechanisms, it has also been proposed that the neuroprotective effects of lithium are key to its therapeutic actions. In this regard, lithium has been shown to reduce the oxidative stress that occurs with multiple episodes of mania and depression. Further, it increases protective proteins such as brain-derived neurotrophic factor and B-cell lymphoma 2, and reduces apoptotic processes through inhibition of glycogen synthase kinase 3 and autophagy. Overall, it is clear that the processes which underpin the therapeutic actions of lithium are sophisticated and most likely inter-related.