Murray et al. (2004) revisited: is bipolar disorder identical to schizophrenia without developmental impairment?

Schizophrenia, Bipolar Disorder and Pre-Attentional Inhibitory Deficits

According to recent findings schizophrenia and bipolar disorder as separate disease entities manifest similarities in neuropsychological functioning. Typical disturbances in both disorders are related to sensory gating deficits characterized by decreased inhibitory functions in responses to various insignificant perceptual signals which are experimentally tested by event related potentials (ERP) and measured P50 wave. In this context, recent findings implicate that disrupted binding and disintegration of consciousness in schizophrenia and bipolar disorder that are related to inhibitory deficits reflected in P50 response may explain similarities in psychotic disturbances in both disorders. With this aim, this review summarizes literature about P50 in both schizophrenia and bipolar disorder.

Overdispersed gene expression in schizophrenia

Schizophrenia (SCZ) is a severe, highly heterogeneous psychiatric disorder with varied clinical presentations. The polygenic genetic architecture of SCZ makes identification of causal variants a daunting task. Gene expression analyses hold the promise of revealing connections between dysregulated transcription and underlying variants in SCZ. However, the most commonly used differential expression analysis often assumes grouped samples are from homogeneous populations and thus cannot be used to detect expression variance differences between samples. Here, we applied the test for equality of variances to normalized expression data, generated by the CommonMind Consortium (CMC), from brains of 212 SCZ and 214 unaffected control (CTL) samples. We identified 87 genes, including VEGFA (vascular endothelial growth factor) and BDNF (brain-derived neurotrophic factor), that showed a significantly higher expression variance among SCZ samples than CTL samples. In contrast, only one gene showed the opposite pattern. To extend our analysis to gene sets, we proposed a Mahalanobis distance-based test for multivariate homogeneity of group dispersions, with which we identified 110 gene sets with a significantly higher expression variability in SCZ, including sets of genes encoding phosphatidylinositol 3-kinase (PI3K) complex and several others involved in cerebellar cortex morphogenesis, neuromuscular junction development, and cerebellar Purkinje cell layer development. Taken together, our results suggest that SCZ brains are characterized by overdispersed gene expression-overall gene expression variability among SCZ samples is significantly higher than that among CTL samples. Our study showcases the application of variability-centric analyses in SCZ research.

Temperament in child and adolescent offspring of patients with schizophrenia and bipolar disorder

Shared vulnerability in offspring of individuals with schizophrenia (SzO) and bipolar disorder (BpO) might manifest early during development through common temperament traits. Temperament dimensions in child and adolescent BpO (N = 80), SzO (N = 34) and the offspring of community controls (CcO) (N = 101) were assessed using the Revised Dimensions of Temperament Survey. The association between temperament dimensions and lifetime psychopathology (including threshold and subthreshold DSM-IV-TR diagnoses) and current socio-academic adjustment was assessed using logistic regression. Fully adjusted models showed that both BpO and SzO scored significantly lower in the positive mood dimension and in the adaptability factor than CcO, with small-medium effect sizes (Cohen's d ~ 0.3-0.5). BpO also scored lower in the activity factor and the activity dimensions than CcO (Cohen's d ~ 0.3). Lower scores in the positive mood dimension were associated with increased risk of impaired adjustment both in BpO [OR 2.30, 95% CI (1.18-4.46)] and in SzO [OR 2.87, 95% CI (1.07-7.66)]. In BpO, lower scores in positive mood were also associated with increased likelihood of internalizing [OR 1.84, 95% CI (1.28-2.64)] and externalizing disorders [OR 1.48, 95% CI (1.01-2.18)]; in SzO, higher scores in activity and flexibility were associated with increased likelihood of internalizing [OR 2.31, 95% CI (1.22-4.38)] and externalizing disorders [OR 3.28, 95% CI (1.2-9)], respectively. Early difficulties in emotion regulation might represent a shared vulnerability phenotype in BpO and SzO. The identification of extreme temperament traits could help to characterize subgroups at greater risk of psychopathology and impaired adjustment, in which targeted interventions are warranted.

Brain change trajectories that differentiate the major psychoses

BACKGROUND

Bipolar disorder and schizophrenia are highly heritable, often chronic and debilitating psychotic disorders that can be difficult to differentiate clinically. Their brain phenotypes appear to overlap in both cross-sectional and longitudinal structural neuroimaging studies, with some evidence to suggest areas of differentiation with differing trajectories. The aim of this review was to investigate the notion that longitudinal trajectories of alterations in brain structure could differentiate the two disorders.

DESIGN

Narrative review. We searched MEDLINE and Web of Science databases in May 2016 for studies that used structural magnetic resonance imaging to investigate longitudinal between-group differences in bipolar disorder and schizophrenia. Ten studies met inclusion criteria, namely longitudinal structural magnetic resonance studies comparing bipolar disorder (or affective psychosis) and schizophrenia within the same study.

RESULTS

Our review of these studies implicates illness-specific trajectories of morphological change in total grey matter volume, and in regions of the frontal, temporal and cingulate cortices. The findings in schizophrenia suggest a trajectory involving progressive grey matter loss confined to fronto-temporal cortical regions. Preliminary findings identify a similar but less severely impacted trajectory in a number of regions in bipolar disorder, however, bipolar disorder is also characterized by differential involvement across cingulate subregions.

CONCLUSION

The small number of available studies must be interpreted with caution but provide initial evidence supporting the notion that bipolar disorder and schizophrenia have differential longitudinal trajectories that are influenced by brain maturation.

Gray Matter Volume Decrease Distinguishes Schizophrenia From Bipolar Offspring During Childhood and Adolescence

OBJECTIVE

There is increasing support toward the notion that schizophrenia and bipolar disorder share neurodevelopmental underpinnings, although areas of divergence remain. We set out to examine gray matter volume characteristics of child and adolescent offspring of patients with schizophrenia or bipolar disorder comparatively.

METHOD

In this 2-center study, magnetic resonance structural neuroimaging data were acquired in 198 children and adolescents (aged 6-17 years): 38 offspring of patients with schizophrenia, 77 offspring of patients with bipolar disorder, and 83 offspring of community controls. Analyses of global brain volumes and voxel-based morphometry (using familywise error correction) were conducted.

RESULTS

There was an effect of group on total cerebral gray matter volume (F = 3.26, p = .041), driven by a decrease in offspring of patients with schizophrenia relative to offspring of controls (p = .035). At a voxel-based level, we observed an effect of group in the left inferior frontal cortex/anterior insula (F = 14.7, p < .001), which was driven by gray matter volume reduction in offspring of patients with schizophrenia relative to both offspring of controls (p = .044) and of patients with bipolar disorder (p < .001). No differences were observed between offspring of patients with bipolar disorder and offspring of controls in either global or voxel-based gray matter volumes.

CONCLUSION

This first comparative study between offspring of patients with schizophrenia and bipolar disorder suggests that gray matter volume reduction in childhood and adolescence may be specific to offspring of patients with schizophrenia; this may index a greater neurodevelopmental impact of risk for schizophrenia relative to bipolar disorder during youth.

The association between cannabis use and mood disorders: A longitudinal study

BACKGROUND

The association between cannabis use and mood disorders is well documented, yet evidence regarding causality is conflicting. This study explored the association between cannabis use, major depressive disorder (MDD) and bipolar disorder (BPD) in a 3-year prospective study.

METHODS

Data was drawn from waves 1 and 2 of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). MDD and BPD were controlled at baseline and defined as meeting full criteria in the 12 months prior to the follow-up. Initiation of cannabis use was defined as any cannabis used by former lifetime abstainers in the time period between baseline and follow-up.

RESULTS

Cannabis use was not significantly associated with increased incidence of MDD (Adjusted Odds Ratio (AOR) for daily use=0.58(0.22-1.51)). Weekly to almost daily cannabis use was associated with increased incidence of BPD ((AOR for weekly to daily use=2.47(1.03-5.92)); daily use was not (AOR=0.52(0.17-1.55)). Baseline MDD was associated with initiation of cannabis use (AOR=1.72(1.1-2.69)). A crude association between baseline BPD and incidence of cannabis use was not maintained in adjusted models (AOR=0.61(0.36-1.04)).

LIMITATIONS

Lack of information regarding frequency of cannabis use at follow-up and limitations regarding generalization of the results.

CONCLUSIONS

Our findings do not support a longitudinal association between cannabis use and incidence of MDD. Results regarding the association between cannabis use and incidence of BPD are conflicting and require further investigation. Baseline MDD, but not BPD, may be associated with future initiation of cannabis use. This may have implications for clinical, social and legislative aspects of cannabis use.

Subclinical psychotic experiences and bipolar spectrum features in depression: association with outcome of psychotherapy

BACKGROUND

Subthreshold psychotic and bipolar experiences are common in major depressive disorder (MDD). However, it is unknown if effectiveness of psychotherapy is altered in depressed patients who display such features compared with those without. The current paper aimed to investigate the impact of the co-presence of subclinical psychotic experiences and subclinical bipolar symptoms on the effectiveness of psychological treatment, alone or in combination with pharmacotherapy.

METHOD

In a naturalistic study, patients with MDD (n = 116) received psychological treatment (cognitive behavioural therapy or interpersonal psychotherapy) alone or in combination with pharmacotherapy. Depression and functioning were assessed six times over 2 years. Lifetime psychotic experiences and bipolar symptoms were assessed at the second time point.

RESULTS

Subclinical psychotic experiences predicted more depression over time (β = 0.20, p < 0.002), non-remission [odds ratio (OR) 7.51, p < 0.016] and relapse (OR 3.85, p < 0.034). Subthreshold bipolar symptoms predicted relapse (OR 1.16, p < 0.037).

CONCLUSIONS

In general, subclinical psychotic experiences have a negative impact on the course and outcome of psychotherapy in MDD. Effects of subclinical bipolar experiences were less prominent.

[Trauma and psychosis--part 1. On the association of early childhood maltreatment in clinical populations with psychotic disorders]

A comprehensive literature stresses a high percentage of severe childhood maltreatment in the history of many psychotically ill patients treated in mental health services. Early childhood abuse seems to be associated among other things with a more severe clinical state, a more chronic course of illness and a more unfavourable psychosocial adaptation. In order not to jump to unwarranted causal conclusions, several conceptual und methodological problems have to be clarified before. From a conceptual perspective psychotic disorders diagnosed according to conventional criteria define only a minor subgroup within a much broader psychosis continuum in general population. Early childhood abuse has to be differentiated according to type, severity, timing, and context. The rates of early childhood abuse are high in general population. The methods of measurement of psychotic symptoms on the one side, of early trauma on the other side have to be critically evaluated. There is an empirically well founded association of childhood maltreatment and psychological and psychosomatic morbidity during adult years in general. In order to establish a potential conditional link also to psychotic disorders, clinical populations have to be compared to adequate control groups at least. A systematic literature search shows a very small number of studies including control groups at all. These studies underline that early childhood abuse may be significantly associated to the risk of psychosis indeed. The conditional role of early childhood abuse, however, has to be investigated only within a multifactorial biopsychosocial model of psychotic illness.

Linear and non-linear associations of symptom dimensions and cognitive function in first-onset psychosis

BACKGROUND

Associations between symptom dimensions and cognition have been mainly studied in non-affective psychosis. The present study investigated whether previously reported associations between cognition and four symptom dimensions (reality distortion, negative symptoms, disorganisation and depression) in non-affective psychosis generalise to a wider spectrum of psychoses. It also extended the research focus to mania, a less studied symptom dimension.

METHODS

Linear and non-linear (quadratic, curvilinear or inverted-U-shaped) associations between cognition and the above five symptom dimensions were examined in a population-based cohort of 166 patients with first-onset psychosis using regression analyses.

RESULTS

Negative symptoms showed statistically significant linear associations with IQ and processing speed, and a significant curvilinear association with verbal memory/learning. Significant quadratic associations emerged between mania and processing speed and mania and executive function. The contributions of mania and negative symptoms to processing speed were independent of each other. The findings did not differ between affective and non-affective psychoses, and survived correction for multiple testing.

CONCLUSIONS

Mania and negative symptoms are associated with distinct patterns of cerebral dysfunction in first-onset psychosis. A novel finding is that mania relates to cognitive performance by a complex response function (inverted-U-shaped relationship). The associations of negative symptoms with cognition include both linear and quadratic elements, suggesting that this dimension is not a unitary concept. These findings cut across affective and non-affective psychoses, suggesting that different diagnostic entities within the psychosis spectrum lie on a neurobiological continuum.

How genes and environmental factors determine the different neurodevelopmental trajectories of schizophrenia and bipolar disorder

The debate endures as to whether schizophrenia and bipolar disorder are separate entities or different manifestations of a single underlying pathological process. Here, we argue that this sterile argument obscures the fact that the truth lies somewhere in between. Thus, recent studies support a model whereby, on a background of some shared genetic liability for both disorders, patients with schizophrenia have been subject to additional genetic and/or environmental factors that impair neurodevelopment; for example, copy number variants and obstetric complications are associated with schizophrenia but not with bipolar disorder. As a result, children destined to develop schizophrenia show an excess of neuromotor delays and cognitive difficulties while those who later develop bipolar disorder perform at least as well as the general population. In keeping with this model, cognitive impairments and brain structural abnormalities are present at first onset of schizophrenia but not in the early stages of bipolar disorder. However, with repeated episodes of illness, cognitive and brain structural abnormalities accumulate in both schizophrenia and bipolar disorder, thus clouding the picture.

[Deconstructing schizophrenia. Dimensional models or division into subtypes?]

Against the background of the arrangements of ICD-11 and DSM-V, future approaches in order to diagnose schizophrenic psychoses are currently being discussed. In this context, the current concepts of schizophrenia are questioned because attempts at neurobiological validation and validation based on family and follow-up studies have not succeeded. Therefore, dimensional diagnostic models or a division into subtypes are suggested. Both of these proposals would imply a deconstruction of the current concept of schizophrenia. A historical review shows that the psychopathological roots of the current discussion can be traced back to Kurt Schneider's nominalistic concept of schizophrenia which is based upon the so-called first-rank symptoms. In contrast, the psychopathological foundation of dimensional concepts and a division into several subtypes date from contributions of Klaus Conrad and Karl Leonhard. A triaxial diagnostic system with the axes of syndromes, course types and aetiology could provide a bridge between the different approaches.

Can obsessions drive you mad? Longitudinal evidence that obsessive-compulsive symptoms worsen the outcome of early psychotic experiences

OBJECTIVE

Although there is substantial comorbidity between psychotic disorder and obsessive-compulsive disorder (OCD), little is known about how these clinical phenotypes, and their subclinical extended phenotypes, covary and impact on each other over time. This study examined cross-sectional and longitudinal associations between both (extended) phenotypes in the general population.

METHOD

Data were obtained from the three waves of the NEMESIS-study. A representative population sample of 7076 participants were assessed using the composite international diagnostic interview (CIDI) at baseline (T(0)), 1 year later at T(1) and again 2 years later at T(2).

RESULTS

At T(0), a lifetime diagnosis of psychotic disorder was present in 1.5% of the entire sample, in 11.5% of the people with any OC symptom and in 23.0% of individuals diagnosed with OCD. OC symptoms at T(0) predicted incident psychotic symptoms at T(2). Similarly, T(0) psychotic symptoms predicted T(2) OC symptoms. The likelihood of persistence of psychotic symptoms or transition to psychotic disorder was higher if early psychosis was accompanied by co-occurring OC symptoms, but not the other way around.

CONCLUSION

OCD and the psychosis phenotype cluster together and predict each other at (sub)clinical level. The co-occurrence of subclinical OC and psychosis may facilitate the formation of a more 'toxic' form of persistent psychosis.

Are psychiatrists an endangered species? Observations on internal and external challenges to the profession

Based on recently voiced concerns about a crisis in psychiatry, six challenges to our profession are identified and discussed. As we approach the revisions of ICD-10 and DSM-IV, the validity of psychiatry's diagnostic definitions and classification systems is increasingly questioned also from inside psychiatry. In addition, confidence in the results of therapeutic intervention studies is waning. A further challenge is the existence of de facto subgroups with opposing ideologies, a situation which is responsible for an unclear role profile of the psychiatrist. Challenges from outside include mounting patient and carer criticism, intrusion of other professions into psychiatry's traditional field of competence, and psychiatry's low status within medicine and in society in general. Studies suggest that the decline of the recruitment into psychiatry, as it is observed in many countries, might be related to problems arising from these challenges. It is unclear whether psychiatry will survive as a unitary medical discipline or whether those segments which are more rewarding, both financially and in status, will break away, leaving the unattractive tasks to carry out by what remains of psychiatry. The demise of the generalist and the rise of the specialist in modern society may contribute to this development. Attempts are underway by professional bodies to define the profile of a "general psychiatrist". Such discussions should be complemented by an analysis of the incentives which contribute to the centrifugal tendencies in psychiatry.