The familial aggregation of psychotic symptoms in bipolar disorder pedigrees

The Nature of the Familial Risk for Psychosis in Bipolar Disorder

BACKGROUND AND HYPOTHESIS

To clarify whether the familial liability to psychosis associated with bipolar disorder (BD) is nonspecific or has a greater effect on risk for psychosis in cases with prominent mood symptoms and/or a remitting course.

STUDY DESIGN

We examined, in 984 809 offspring raised in intact families in Sweden, born 1980-1996 and followed-up through 2018, by multivariable Cox proportional hazards regression, risk in offspring of parents with BD for 7 psychotic disorders: Psychotic MD (PMD), psychotic BD (PBD), schizoaffective disorder (SAD), acute psychoses, psychosis NOS, delusional disorder (DD) and schizophrenia (SZ). Diagnoses were obtained from national registers.

STUDY RESULTS

In the offspring of BD parents, the hazard ratios (HR) for these 7 disorders formed an inverted U-shaped curve, rising from 2.98 for PMD, to peak at 4.49 for PBD and 5.25 for SAD, and then declining to a HR of 3.48 for acute psychoses and 3.22 for psychosis NOS, to a low of 2.19 for DD and 2.33 for SZ. A similar pattern of risks was seen in offspring of mothers and fathers affected with BD and in offspring predicted from age at onset in their BD parent.

CONCLUSIONS

The BD-associated risk for psychosis impacts most strongly on mood disorders, moderately on episodic psychotic syndromes, and least on chronic psychotic disorders. These results support prior clinical studies suggesting a qualitative difference in the familial substrate for psychosis occurring in BD and SZ.

Parental consanguinity among patients with schizophrenia in a rural community of South India: A clinical and genetic investigation

BACKGROUND

Studies from certain regions of the world indicate that consanguineous marriages are a risk factor for the development of schizophrenia in offspring. However the evidence is inconsistent partly due to methodological limitation of which hospital based recruitment contributing to significant bias. The studies from the Indian subcontinent, is scarce, where rates of consanguinity is high.

METHODS

The schizophrenia patients living in a geographically defined rural south Indian community and randomly selected controls dwelling in the same community sharing sociocultural, economic and lifestyle factors were recruited. They were assessed for parental consanguinity using the clinical interviews as well as DNA-based estimates. The latter was conducted by calculating the coefficient of inbreeding 'f'. A participant was considered to have consanguineous parentage if his/her parents shared a common ancestor no more remote than a great-great-grandparent, corresponding to DNA-based estimates of 'f' ≥ 0.0156.

RESULTS

The rates of parental consanguinity assessed by clinical interview were comparable in both groups (Cases: 10.71 %, Controls: 7.25 %; χ² = 0.493, p = 0.4825). However, DNA-based rates of parental consanguinity showed that 'f' was significantly higher among cases than controls (Mann-Whitney U = 11315.5; p = 0.022). Seventy-five cases (62.5 %) and 108 control participants (48.6 %) had 'f' ≥ 0.0156 (χ² = 6.008; p = 0.014). The results were consistent across different quality control measures.

CONCLUSION

Schizophrenia is associated with higher parental consanguinity, suggesting a role for multiple recessive risk alleles in its etiology. Replication in future studies in diverse settings would add further strength to this.

Terminology and assessment tools of psychosis: A systematic narrative review

AIM

Phenomena within the psychosis continuum that varies in frequency/duration/intensity have been increasingly identified. Different terms describe these phenomena, however there is no standardization within the terminology. This review evaluated the definitions and assessment tools of seven terms - (i) 'psychotic experiences'; (ii) 'psychotic-like experiences'; (iii) 'psychotic-like symptoms'; (iv) 'attenuated psychotic symptoms'; (v) 'prodromal psychotic symptoms'; (vi) 'psychotic symptomatology'; and (vii) 'psychotic symptoms'.

METHODS

EMBASE, MEDLINE, and CINAHL were searched during February-March 2019. Inclusion criteria included 1989-2019, full text, human, and English. Papers with no explicit definition or assessment tool, duplicates, conference abstracts, systematic reviews, meta-analyses, or no access were excluded.

RESULTS

A total of 2238 papers were identified and of these, 627 were included. Definitions and assessment tools varied, but some trends were found. Psychotic experiences and psychotic-like experiences were transient and mild, found in the general population and those at-risk. Psychotic-like symptoms were subthreshold and among at-risk populations and non-psychotic mental disorders. Attenuated psychotic symptoms were subthreshold but associated with distress, risk, and help-seeking. Prodromal psychotic symptoms referred to the prodrome of psychotic disorders. Psychotic symptomatology included delusions and hallucinations within psychotic disorders. Psychotic symptoms was the broadest term, encompassing a range of populations but most commonly involving hallucinations, delusions, thought disorder, and disorganization.

DISCUSSION

A model for conceptualizing the required terms is proposed and future directions needed to advance this field of research are discussed.

AKT1 and genetic vulnerability to bipolar disorder

AKT1 encodes a serine/threonine kinase that has as one of its best-known substrates glycogen synthase kinase-3 (GSK3), a primary target for lithium. AKT1 has been previously been implicated as a vulnerability gene for bipolar disorder (BD). We aimed to associate genetic variants in the AKT1 gene with subgroups of BD. BD patients from a Swedish cohort (N = 831) were phenotyped in regards to their psychotic episodes according to mood-congruence in depression and manias, and compared to controls (N = 1,496). All participants were genotyped for SNPs in AKT1 previously implicated to have a role: rs3730358, rs1130214 and rs3803300. None of the effects reported in earlier studies were statistically significant, including the association between rs3803300 and BD without any psychotic symptoms, rs3803300 and mood-congruent psychosis, rs3803300 and the combined groups, as well as the association between the haplotypes formed by rs3730358 and rs1130214 and risk for BD. In a Bayesian analysis, all Bayes' Factors using default priors supported the null hypothesis in the replication set by a factor of between 5 and 1300 times. Analysis of genome wide association data did not reveal any association between BD and the AKT1 region. We conclude AKT1 is less likely to be a vulnerability gene in BD.

Interaction of reelin and stress on immobility in the forced swim test but not dopamine-mediated locomotor hyperactivity or prepulse inhibition disruption: Relevance to psychotic and mood disorders

RATIONALE

Psychotic disorders, such as schizophrenia, as well as some mood disorders, such as bipolar disorder, have been suggested to share common biological risk factors. One such factor is reelin, a large extracellular matrix glycoprotein that regulates neuronal migration during development as well as numerous activity-dependent processes in the adult brain. The current study sought to evaluate whether a history of stress exposure interacts with endogenous reelin levels to modify behavioural endophenotypes of relevance to psychotic and mood disorders.

METHODS

Heterozygous Reeler Mice (HRM) and wildtype (WT) controls were treated with 50mg/L of corticosterone (CORT) in their drinking water from 6 to 9weeks of age, before undergoing behavioural testing in adulthood. We assessed methamphetamine-induced locomotor hyperactivity, prepulse inhibition (PPI) of acoustic startle, short-term spatial memory in the Y-maze, and depression-like behaviour in the Forced-Swim Test (FST).

RESULTS

HRM genotype or CORT treatment did not affect methamphetamine-induced locomotor hyperactivity, a model of psychosis-like behaviour. At baseline, HRM showed decreased PPI at the commonly used 100msec interstimulus interval (ISI), but not at the 30msec ISI or following challenge with apomorphine. A history of CORT exposure potentiated immobility in the FST amongst HRM, but not WT mice. In the Y-maze, chronic CORT treatment decreased novel arm preference amongst HRM, reflecting reduced short-term spatial memory.

CONCLUSION

These data confirm a significant role of endogenous reelin levels on stress-related behaviour, supporting a possible role in both bipolar disorder and schizophrenia. However, an interaction of reelin deficiency with dopaminergic regulation of psychosis-like behaviour remains unclear.

Schizophrenia, Not a Psychotic Disorder: Bleuler Revisited

Current diagnostic criteria delineate schizophrenia as a discrete entity essentially defined by positive symptoms. However, the role of positive symptoms in psychiatry is being questioned. There is compelling evidence that psychotic manifestations are expressed in the population in a continuum of varying degrees of severity, ranging from normality to full-blown psychosis. In most cases, these phenomena do not persist, but they constitute risk factors for psychiatric disorders in general. Psychotic symptoms are also present in most non-psychotic psychiatric diagnoses, being a marker of severity. Research revealed that hallucinations and delusions appear to have distinct, independent biological underpinnings-in the general population, in psychotic, and in non-psychotic disorders as well. On the other hand, negative symptoms were seen to be far more restricted to schizophrenia, have other underlying pathophysiology than positive symptoms, predict outcome and treatment response in schizophrenia, and start before the first psychotic outbreak. The current work discusses the concept of schizophrenia, suggesting that a greater emphasis should be put on cases where psychotic symptoms emerge in a premorbid subtly increasing negative/cognitive symptoms background. In those cases, psychosis would have a different course and outcome while psychosis occurring in the absence of such background deterioration would be more benign-probably having no, or a milder, underlying degenerative process. This reformulation should better drive psychopathological classification, face positive symptoms as epiphenomenon of the schizophrenia process, and dishevel stigma from schizophrenia and from delusions and hallucinations.

Impact of psychosis in bipolar disorder during manic episodes. Int J Neurosci 2018;128:1128-1134. [PMID: 29888994 DOI: 10.1080/00207454.2018.1486833]

OBJECTIVES

To evaluate the effect of psychosis on prognosis as measured by the course of a manic episode, symptoms severity and time to remission and identify existing differences in positive and negative symptoms between psychotic and non-psychotic patients.

STUDY DESIGN

40 bipolar patients presenting with a diagnosis of acute mania were enrolled (18 psychotic patients and 22 non-psychotic patients) in this cross-sectional study. Subjects were required to complete two self-reported questionnaires, the Young Mania Rating Scale (YMRS) for manic symptoms, and Positive and Negative Symptoms Scale (PANSS) for psychotic symptoms. Rating scales were administered at baseline and then again after three weeks of pharmacologic treatment.

RESULTS

There were no differences in socio-demographic characteristics between psychotic and non-psychotic subjects. Psychosis was associated with higher scores on the YMRS and PANSS (increased symptoms severity), compared to non-psychotic patients. Both groups demonstrated clinical improvement and remission, with scores amongst psychotic patients remaining higher. Groups were similar in symptomatology except with regards to psychotic symptoms (the content, insight, delusions, hallucinations, grandiosity, poor rapport and unusual thoughts).

CONCLUSIONS

Psychosis can be considered a severity index in bipolar disorder, with decreased severity and overall clinical improvement and remission taking place in response to pharmacotherapy.

Psychosis in bipolar disorder: Does it represent a more "severe" illness?

OBJECTIVES

Although there is a common clinical assumption that bipolar disorder with psychotic features reflects greater severity than bipolar disorder without psychosis, the existing empirical literature is mixed. This study investigated the phenomenology of psychosis as well as demographic, clinical, functional, and neuropsychological features in a large, cross-sectional sample of participants with bipolar disorder divided by history of psychosis.

METHODS

In a large single study, 168 affective-only bipolar disorder (BP-A) participants and 213 bipolar disorder with a history of psychosis (BP-P) participants completed a comprehensive clinical diagnostic interview and neuropsychological testing. t tests, chi-square tests, and Bayes factors were used to investigate group differences or lack thereof.

RESULTS

The prevalence of psychosis in this sample (53%) was similar to published reports. Nearly half of BP-P participants experienced grandiose delusions, and relatively few endorsed "first-rank" hallucinations of running commentary or two or more voices conversing. There were no demographic or neuropsychological differences between groups. BP-A participants experienced greater chronicity of affective symptoms and a greater degree of rapid cycling than BP-P participants; there were no other clinical differences between groups.

CONCLUSIONS

Overall, these results contradict the conventional notion that bipolar disorder with psychotic features represents a more severe illness than bipolar disorder without a history of psychosis. The presence of psychosis does not appear to be associated with poorer clinical/functional outcome or suggest a greater degree of neuropsychological impairment; conversely, the absence of psychosis was associated with affective chronicity and rapid cycling. Nosological and treatment implications are discussed.

Positive Traits in the Bipolar Spectrum: The Space between Madness and Genius

Bipolar disorder is a severe, lifelong mood disorder for which little is currently understood of the genetic mechanisms underlying risk. By examining related dimensional phenotypes, we may further our understanding of the disorder. Creativity has a historical connection with the bipolar spectrum and is particularly enhanced among unaffected first-degree relatives and those with bipolar spectrum traits. This suggests that some aspects of the bipolar spectrum may confer advantages, while more severe expressions of symptoms negatively influence creative accomplishment. Creativity is a complex, multidimensional construct with both cognitive and affective components, many of which appear to reflect a shared genetic vulnerability with bipolar disorder. It is suggested that a subset of bipolar risk variants confer advantages as positive traits according to an inverted-U-shaped curve with clinically unaffected allele carriers benefitting from the positive traits and serving to maintain the risk alleles in the population. The association of risk genes with creativity in healthy individuals (e.g., NRG1), as well as an overall sharing of common genetic variation between bipolar patients and creative individuals, provides support for this model. Current findings are summarized from a multidisciplinary perspective to demonstrate the feasibility of research in this area to reveal the mechanisms underlying illness.

Neurocognitive performance, psychopathology and social functioning in individuals at high risk for schizophrenia or psychotic bipolar disorder

INTRODUCTION

Although cognitive deficits are consistent endophenotypes of schizophrenia and bipolar disorder, findings in psychotic bipolar disorder (BDP) are inconsistent. In this study we compared adult unaffected first-degree relatives of schizophrenia and BDP patients on cognition, psychopathology, social functioning and quality of life.

METHODS

Sixty-six unaffected first-degree relatives of schizophrenia patients (SUnR), 36 unaffected first-degree relatives of BDP patients (BDPUnR) and 102 controls participated in the study. Between-group differences were examined and Discriminant Function Analysis (DFA) predicted group membership.

RESULTS

Visual memory, control inhibition, working memory, cognitive flexibility and abstract reasoning were linearly impaired in the relatives' groups. Poorer verbal fluency and processing speed were evident only in the SUnR group. The SUnR group had higher depressive and somatization symptoms while the BDPUnR group had higher anxiety and lower social functioning compared with the controls. Individuals with superior cognition were more likely to be classified as controls; those with higher social functioning, prolonged processing speed and lower anxiety were more likely to be classified as SUnR.

LIMITATIONS

The relatives' sample is quite heterogeneous; the effects of genetic or environmental risk-factors were not examined.

CONCLUSIONS

Cognitive functions mediated by a fronto-parietal network, show linear impairments in unaffected relatives of BDP and schizophrenia patients; processing speed and verbal fluency impairments were evident only in schizophrenia relatives. Self-perceived symptomatology and social functioning also differ between schizophrenia and BDP relatives. The continuum seen in patients in several indices was also seen in the cognitive impairments in unaffected relatives of schizophrenia and BDP patients.

Characteristics of depressive patients according to family history of affective illness: Findings from a French national cohort

BACKGROUND

Literature is scarce about the characteristics of mood disorder patients with a family history (FH) of affective illness. The aim of the current study was to compare the prominent features of depressive patients with a FH of mania (FHM), those of depressive patients with a FH of depression (FHD), and those of depressive patients with no FH of affective illness (FHO).

METHODS

As part of the EPIDEP National Multisite French Study of 493 consecutive DSM-IV major depressive patients evaluated in at least two semi-structured interviews 1 month apart, 45 (9.1%) were classified as FHM, 210 (42.6%) as FHD, and 238 (48.3%) as FHO.

RESULTS

The main characteristics of FHM patients were a cyclothymic temperament, the presence of mixed features and diurnal variations of mood during depression, early sexual behaviour, a high number of mood episodes and hypomanic switches, high rates of suicide attempts and rapid cycling; diagnosis of bipolar disorder was more frequent in this group as well as comorbid obsessive compulsive disorder, posttraumatic stress disorder, bulimia, attention deficit/hyperactivity disorder and impulse control disorders. The FHD patients had more depressive temperament, generalized anxiety disorder, and anorexia nervosa. Compared to FHO, FHM and FHD showed an earlier age at onset, more comorbid anxiety disorders, as well as more psychotic features.

LIMITATIONS

The following are the limitations of this study: retrospective design, recall bias, and preferential enrolment of bipolar patients with a depressive predominant polarity.

CONCLUSIONS

In light of genetic studies conducted in affective disorder patients, our findings may support the hypothesis of genetic risks factors common to affective disorders and dimensions of temperament, that may extend to comorbid conditions specifically associated with bipolar or unipolar illness.

Neural correlates of hallucinations in bipolar disorder

Objective:

Approximately one-half of all patients affected by bipolar disorder present with psychotic features on at least one occasion. Several studies have found that alterations in the activity of mesolimbic and prefrontal regions are related to aberrant salience in psychotic patients. The aim of the present study was to investigate the structural correlates of a history of hallucinations in a sample of euthymic patients with bipolar I disorder (BD-I).

Methods:

The sample consisted of 21 euthymic patients with BD-I and no comorbid axis I DSM-IV-TR disorders. Voxel based morphometry (VBM) was used to compare patients with and without a lifetime history of hallucinations. Preprocessing was performed using the Diffeomorphic Anatomical Registration through Exponentiated Lie Algebra (DARTEL) algorithm for VBM in SPM8. Images were processed using optimized VBM.

Results:

The main finding of the present study was a reduction in gray matter volume in the right posterior insular cortex of patients with BD-I and a lifetime history of hallucinations, as compared to subjects with the same diagnosis but no history of hallucinations.

Conclusions:

This finding supports the presence of abnormalities in the salience network in BD patients with a lifetime history of hallucinations. These alterations may be associated with an aberrant assignment of salience to the elements of one’s own experience, which could result in psychotic symptoms.

A comprehensive analysis of NDST3 for schizophrenia and bipolar disorder in Han Chinese

A novel susceptibility locus (rs11098403) for schizophrenia and bipolar disorder (BD) was identified in an Ashkenazi Jewish population by a recent large-scale genome-wide association study. The rs11098403 is located in the vicinity of the gene encoding N-deacetylase/N-sulfotransferase (heparan glucosaminyl) 3, (NDST3). This study aimed to replicate the results in a Han Chinese population and then potentially extend these findings. We performed a two-stage study to investigate the association of NDST3 with the schizophrenia and BD risk in the Han Chinese. In stage 1, a total of 632 patients with schizophrenia, 654 patients with BD and 684 healthy controls were recruited from the Shanghai region. In stage 2, 522 schizophrenia patients and 547 normal subjects were enrolled from the Hangzhou region. Then, we conducted a meta-analysis based on the present literature. In stage 1, the single nucleotide polymorphism (SNP) rs11098403 showed a significant association with schizophrenia (corrected P=0.005). The frequency of the rs11098403 G allele was significantly lower among schizophrenia patients than among the controls (odds ratio (OR)=0.68, 95% confidence interval (CI): 0.55-0.84, corrected P=0.002). No significant difference was observed in individual SNP marker genotypes or allele distributions between the BD and control groups. In stage 2, the association of rs11098403 with schizophrenia could be validated (genotypic P=0.001 and allelic P=0.0003). After pooling all data from 1861 patients with schizophrenia and 2081 controls, we observed a significant association of the rs11098403 G allele with schizophrenia (Z=5.56, P<0.001), with an OR=0.70 (95% CI: 0.61-0.79). Then, we performed an expression quantitative trait loci analysis to investigate the functional effect of rs11098403 on NDST3 expression in the brain. We observed a significant association of rs11098403 with NDST3 expression in the hippocampus (P=0.027), although the significance did not survive after multiple testing correction. Our findings provided preliminary evidence that rs11098403 might modify the genetic risk of schizophrenia in the Han Chinese. Further investigations are warranted to identify the precise mechanism regulating brain NDST3 expression in the Han Chinese. These results would help to explain the pathophysiological mechanism of schizophrenia.

A latent class analysis of parental bipolar disorder: Examining associations with offspring psychopathology

Bipolar disorder (BD) is highly heterogeneous, and course variations are associated with patient outcomes. This diagnostic complexity challenges identification of patients in greatest need of intervention. Additionally, course variations have implications for offspring risk. First, latent class analysis (LCA) categorized parents with BD based on salient illness characteristics: BD type, onset age, polarity of index episode, pole of majority of episodes, rapid cycling, psychosis, anxiety comorbidity, and substance dependence. Fit indices favored three parental classes with some substantively meaningful patterns. Two classes, labeled "Earlier-Onset Bipolar-I" (EO-I) and "Earlier-Onset Bipolar-II" (EO-II), comprised parents who had a mean onset age in mid-adolescence, with EO-I primarily BD-I parents and EO-II entirely BD-II parents. The third class, labeled "Later-Onset BD" (LO) had an average onset age in adulthood. Classes also varied on probability of anxiety comorbidity, substance dependence, psychosis, rapid cycling, and pole of majority of episodes. Second, we examined rates of disorders in offspring (ages 4-33, Mage=13.46) based on parental latent class membership. Differences emerged for offspring anxiety disorders only such that offspring of EO-I and EO-II parents had higher rates, compared to offspring of LO parents, particularly for daughters. Findings may enhance understanding of BD and its nosology.

Familiality and SNP heritability of age at onset and episodicity in major depressive disorder

BACKGROUND

Strategies to dissect phenotypic and genetic heterogeneity of major depressive disorder (MDD) have mainly relied on subphenotypes, such as age at onset (AAO) and recurrence/episodicity. Yet, evidence on whether these subphenotypes are familial or heritable is scarce. The aims of this study are to investigate the familiality of AAO and episode frequency in MDD and to assess the proportion of their variance explained by common single nucleotide polymorphisms (SNP heritability).

METHOD

For investigating familiality, we used 691 families with 2-5 full siblings with recurrent MDD from the DeNt study. We fitted (square root) AAO and episode count in a linear and a negative binomial mixed model, respectively, with family as random effect and adjusting for sex, age and center. The strength of familiality was assessed with intraclass correlation coefficients (ICC). For estimating SNP heritabilities, we used 3468 unrelated MDD cases from the RADIANT and GSK Munich studies. After similarly adjusting for covariates, derived residuals were used with the GREML method in GCTA (genome-wide complex trait analysis) software.

RESULTS

Significant familial clustering was found for both AAO (ICC = 0.28) and episodicity (ICC = 0.07). We calculated from respective ICC estimates the maximal additive heritability of AAO (0.56) and episodicity (0.15). SNP heritability of AAO was 0.17 (p = 0.04); analysis was underpowered for calculating SNP heritability of episodicity.

CONCLUSIONS

AAO and episodicity aggregate in families to a moderate and small degree, respectively. AAO is under stronger additive genetic control than episodicity. Larger samples are needed to calculate the SNP heritability of episodicity. The described statistical framework could be useful in future analyses.

New developments in the genetics of bipolar disorder

The last several years have been breakthrough ones in bipolar disorder (BPD) genetics, as the field has identified robust risk variants for the first time. Leading the way have been genome-wide association studies (GWAS) that have assessed common genetic markers across very large groups of patients and controls. These have resulted in findings in genes including ANK3, CACNA1C, SYNE1, ODZ4, and TRANK1. Additional studies have begun to examine the biology of these genes and how risk variants influence aspects of brain and behavior that underlie BPD. For example, carriers of the CACNA1C risk variant have been found to exhibit hippocampal and anterior cingulate dysfunction during episodic memory recall. This work has shed additional light on the relationship of bipolar susceptibility variants to other disorders, particularly schizophrenia. Even larger BPD GWAS are expected with samples now amassed of 21,035 cases and 28,758 controls. Studies have examined the pharmacogenomics of BPD with studies of lithium response, yielding high profile results that remain to be confirmed. The next frontier in the field is the identification of rare bipolar susceptibility variants through large-scale DNA sequencing. While only a couple of papers have been published to date, many studies are underway. The Bipolar Sequencing Consortium has been formed to bring together all of the groups working in this area, and to perform meta-analyses of the data generated. The consortium, with 13 member groups, now has exome data on ~3,500 cases and ~5,000 controls, and on ~162 families. The focus will likely shift within several years from exome data to whole genome data as costs of obtaining such data continue to drop. Gene-mapping studies are now providing clear results that provide insights into the pathophysiology of the disorder. Sequencing studies should extend this process further. Findings could eventually set the stage for rational therapeutic development.

Resting state electroencephalogram oscillatory abnormalities in schizophrenia and psychotic bipolar patients and their relatives from the bipolar and schizophrenia network on intermediate phenotypes study

BACKGROUND

Abnormal resting state electroencephalogram (EEG) oscillations are reported in schizophrenia (SZ) and bipolar disorder, illnesses with overlapping symptoms and genetic risk. However, less evidence exists on whether similar EEG spectral abnormalities are present in individuals with both disorders or whether these abnormalities are present in first-degree relatives, possibly representing genetic predisposition for these disorders.

METHODS

Investigators examined 64-channel resting state EEGs of 225 SZ probands and 201 first-degree relatives (SZR), 234 psychotic bipolar (PBP) probands and 231 first-degree relatives (PBPR), and 200 healthy control subjects. Eight independent resting state EEG spectral components and associated spatial weights were derived using group independent component analysis. Analysis of covariance was conducted on spatial weights to evaluate group differences. Relative risk estimates and familiality were evaluated on abnormal spectral profiles in probands and relatives.

RESULTS

Both SZ and PBP probands exhibited increased delta, theta, and slow and fast alpha activity. Post-hoc pair-wise comparison revealed increased frontocentral slow beta activity in SZ and PBP probands as well as SZR and PBPR. Augmented frontal delta activity was exhibited by SZ probands and SZR, whereas PBP probands and PBPR showed augmented fast alpha activity.

CONCLUSIONS

Both SZ and PBP probands demonstrated aberrant low-frequency activity. Slow beta activity was abnormal in SZ and PBP probands as well as SZR and PBPR perhaps indicating a common endophenotype for both disorders. Delta and fast alpha activity were unique endophenotypes for SZ and PBP probands, respectively. The EEG spectral activity exhibited moderate relative risk and heritability estimates, serving as intermediate phenotypes in future genetic studies for examining biological mechanisms underlying the pathogenesis of the two disorders.

Mood congruence phenomenon in acutely symptomatic mania bipolar I disorder patients with and without psychotic symptoms

INTRODUCTION

Bipolar disorder causes substantial morbidity including cognitive impairment. The objective of the study was to evaluate memory performance of acutely mania bipolar I disorder (BD-I) patients with and without psychosis. We also aimed to assess the mood congruence phenomenon upon memory.

METHODS

A cross-sectional study was developed with BD-I patients (19 with, and 12 without psychotic symptoms), and 27 age- and education-paired healthy controls. Memory tests were selected to evaluate memory/attention performance. A verbal episodic memory task with affective content (word span) was also applied.

RESULTS

A significant difference was observed in the scores of the word span task with positive tone among the three groups, controlling for number of mania episodes (p=.042). Nonpsychotic BD patients presented higher scores. There was a statistical tendency for BD-I patients with and without psychotic symptoms to perform poorer than healthy controls in the delayed recall of the logical memory test (p=.069).

CONCLUSION

Psychotic and nonpsychotic mania BD-I patients showed mood congruence phenomenon in a verbal memory task with positive tone in relation to the healthy group. Evidence of mood congruence was found in the nonpsychotic group suggesting a purer manifestation of the disease.

Distinguishing between schizophrenia and other psychotic disorders

The Diagnostic and Statistical Manual of Mental Disorders (DSM) has provided diagnostic reliability across observers while neglecting biological validity. The current theme issue explores the boundaries between schizophrenia and bipolar disorder, using neuro-cognition, systems neuroscience, and genetics as points of departure to begin consideration of a biologically based reclassification of these illnesses.

Resting state functional connectivity of five neural networks in bipolar disorder and schizophrenia

BACKGROUND

Bipolar disorder (BPD) and schizophrenia (SCZ) share clinical characteristics and genetic contributions. Functional dysconnectivity across various brain networks has been reported to contribute to the pathophysiology of both SCZ and BPD. However, research examining resting-state neural network dysfunction across multiple networks to understand the relationship between these two disorders is lacking.

METHODS

We conducted a resting-state functional connectivity fMRI study of 35 BPD and 25 SCZ patients, and 33 controls. Using previously defined regions-of-interest, we computed the mean connectivity within and between five neural networks: default mode (DM), fronto-parietal (FP), cingulo-opercular (CO), cerebellar (CER), and salience (SAL). Repeated measures ANOVAs were used to compare groups, adjusting false discovery rate to control for multiple comparisons. The relationship of connectivity with the SANS/SAPS, vocabulary and matrix reasoning was investigated using hierarchical linear regression analyses.

RESULTS

Decreased within-network connectivity was only found for the CO network in BPD. Across groups, connectivity was decreased between CO-CER (p<0.001), to a larger degree in SCZ than in BPD. In SCZ, there was also decreased connectivity in CO-SAL, FP-CO, and FP-CER, while BPD showed decreased CER-SAL connectivity. Disorganization symptoms were predicted by connectivity between CO-CER and CER-SAL.

DISCUSSION

Our findings indicate dysfunction in the connections between networks involved in cognitive and emotional processing in the pathophysiology of BPD and SCZ. Both similarities and differences in connectivity were observed across disorders. Further studies are required to investigate relationships of neural networks to more diverse clinical and cognitive domains underlying psychiatric disorders.

Patients with bipolar disorders share similar but attenuated prospective memory impairments with patients with schizophrenia

BACKGROUND

Prospective memory (PM) refers to the ability to remember to carry out an intended action in the future. PM is consistently found to be impaired in individuals with schizophrenia. Bipolar disorder and schizophrenia may represent conditions along a continuum, and share similar neurocognitive and genetic architecture. This study aimed to compare the nature and extent of PM impairment in individuals with schizophrenia and bipolar disorder.

METHOD

Participants were 38 out-patients with schizophrenia and 40 out-patients with bipolar disorder in an early psychosis intervention programme, and 37 healthy controls. Time-, event- and activity-based PMs were assessed using a dual-task laboratory paradigm. Self-reported PM performance was gauged using the Prospective and Retrospective Memory Questionnaire. Analysis of covariance (ANCOVA), with intelligence quotient (IQ) and education included as covariates, was used to examine group difference on various types of PM. Repeated measures of ANCOVA were used to examine the group × PM type interaction effect. Correspondence between laboratory and self-reported PM measures was examined using correlational analysis.

RESULTS

The group × PM type interaction effect was not significant, but the main effect of group was significant. Patients with schizophrenia and patients with bipolar disorder both performed more poorly than healthy participants in PM. The two clinical groups did not significantly differ in PM. Laboratory and self-reported PM measures did not correlate significantly with each other.

CONCLUSIONS

Patients with bipolar disorder shared a similar PM impairment with those with schizophrenia. Findings of this study extended the similarity in neurocognitive impairments between the two psychiatric disorders to PM.

Relation between variants in the neurotrophin receptor gene, NTRK3, and white matter integrity in healthy young adults

The NTRK3 gene (also known as TRKC) encodes a high affinity receptor for the neurotrophin 3'-nucleotidase (NT3), which is implicated in oligodendrocyte and myelin development. We previously found that white matter integrity in young adults is related to common variants in genes encoding neurotrophins and their receptors. This underscores the importance of neurotrophins for white matter development. NTRK3 variants are putative risk factors for schizophrenia, bipolar disorder, and obsessive-compulsive disorder hoarding, suggesting that some NTRK3 variants may affect the brain. To test this, we scanned 392 healthy adult twins and their siblings (mean age, 23.6 ± 2.2 years; range: 20-29 years) with 105-gradient 4-Tesla diffusion tensor imaging (DTI). We identified 18 single nucleotide polymorphisms (SNPs) in the NTRK3 gene that have been associated with neuropsychiatric disorders. We used a multi-SNP model, adjusting for family relatedness, age, and sex, to relate these variants to voxelwise fractional anisotropy (FA) - a DTI measure of white matter integrity. FA was optimally predicted (based on the highest false discovery rate critical p), by five SNPs (rs1017412, rs2114252, rs16941261, rs3784406, and rs7176429; overall FDR critical p=0.028). Gene effects were widespread and included the corpus callosum genu and inferior longitudinal fasciculus - regions implicated in several neuropsychiatric disorders and previously associated with other neurotrophin-related genetic variants in an overlapping sample of subjects. NTRK3 genetic variants, and neurotrophins more generally, may influence white matter integrity in brain regions implicated in neuropsychiatric disorders.

Global prefrontal and fronto-amygdala dysconnectivity in bipolar I disorder with psychosis history

BACKGROUND

Pathophysiological models of bipolar disorder postulate that mood dysregulation arises from fronto-limbic dysfunction, marked by reduced prefrontal cortex (PFC) inhibitory control. This might occur due to both disruptions within PFC networks and abnormal inhibition over subcortical structures involved in emotional processing. However, no study has examined global PFC dysconnectivity in bipolar disorder and tested whether regions with within-PFC dysconnectivity also exhibit fronto-limbic connectivity deficits. Furthermore, no study has investigated whether such connectivity disruptions differ for bipolar patients with psychosis history, who might exhibit a more severe clinical course.

METHODS

We collected resting-state functional magnetic resonance imaging at 3T in 68 remitted bipolar I patients (34 with psychosis history) and 51 demographically matched healthy participants. We employed a recently developed global brain connectivity method, restricted to PFC (rGBC). We also independently tested connectivity between anatomically defined amygdala and PFC.

RESULTS

Bipolar patients exhibited reduced medial prefrontal cortex (mPFC) rGBC, increased amygdala-mPFC connectivity, and reduced connectivity between amygdala and dorsolateral PFC. All effects were driven by psychosis history. Moreover, the magnitude of observed effects was significantly associated with lifetime psychotic symptom severity.

CONCLUSIONS

This convergence between rGBC, seed-based amygdala findings, and symptom severity analyses highlights that mPFC, a core emotion regulation region, exhibits both within-PFC dysconnectivity and connectivity abnormalities with limbic structures in bipolar illness. Furthermore, lateral PFC dysconnectivity in patients with psychosis history converges with published work in schizophrenia, indicating possible shared risk factors. Observed dysconnectivity in remitted patients suggests a bipolar trait characteristic and might constitute a risk factor for phasic features of the disorder.

Predictors of lithium response in bipolar disorder

While lithium is generally regarded as the first-line agent for patients with bipolar disorder, it does not work for everyone, which raises the question: can we predict who will be most likely to respond? In this paper, we review the most compelling clinical, biologic, and genetic predictors of lithium response in bipolar disorder. Among clinical factors, the strongest predictors of good response are fewer hospitalizations preceding treatment, an episodic course characterized by an illness pattern of mania followed by depression, and a later age at onset of bipolar disorder. While several biologic predictors have been studied, the results are preliminary and require replication with studies of larger patient samples over longer observation periods. Neuroimaging is a particularly promising method given that it might concurrently illuminate pathophysiologic underpinnings of bipolar disorder, the mechanism of action of lithium, and potential predictors of lithium response. The first genome-wide association study of lithium response was recently completed. No definitive results emerged, perhaps because the study was underpowered. With major new initiatives in progress aiming to identify genes and genetic variations associated with lithium response, there is much reason to be hopeful that clinically useful information might be generated within the next several years. This could ultimately translate into tests that could guide the choice of mood-stabilizing medication for patients. In addition, it might facilitate pharmacologic research aimed at developing newer, more effective medications that might act more quickly and yield fewer side effects.

Relational memory in psychotic bipolar disorder

OBJECTIVES

Recent research has highlighted the phenotypic and genetic overlap of bipolar disorder and schizophrenia. Cognitive deficits in bipolar disorder parallel those seen in schizophrenia, particularly for bipolar disorder patients with a history of psychotic features. Here we explored whether relational memory deficits, which are prominent in schizophrenia, are also present in patients with psychotic bipolar disorder.

METHODS

We tested 25 patients with psychotic bipolar disorder on a relational memory paradigm previously employed to quantify deficits in schizophrenia. During the training, participants learned to associate a set of faces and background scenes. During the testing, participants viewed a single background overlaid by three trained faces and were asked to recall the matching face, which was either present (Match trials) or absent (Non-Match trials). Explicit recognition and eye-movement data were collected and compared to those for 28 schizophrenia patients and 27 healthy subjects from a previously published dataset.

RESULTS

Contrary to our prediction, we found psychotic bipolar disorder patients were less impaired in relational memory than schizophrenia subjects. Bipolar disorder subjects showed eye-movement behavior similar to healthy controls, whereas schizophrenia subjects were impaired relative to both groups. However, bipolar disorder patients with current delusions and/or hallucinations were more impaired than bipolar disorder patients not currently experiencing these symptoms.

CONCLUSIONS

We found that patients with psychotic bipolar disorder had better relational memory performance than schizophrenia patients, indicating that a history of psychotic symptoms does not lead to a significant relational memory deficit.

Gray matter volume in schizophrenia and bipolar disorder with psychotic features

There is growing evidence that schizophrenia (SZ) and bipolar disorder (BD) overlap significantly in risk factors, neurobiological features, clinical presentations, and outcomes. SZ is characterized by well documented gray matter (GM) abnormalities in multiple frontal, temporal and subcortical structures. Recent voxel-based morphometry (VBM) studies and meta-analyses in BD also report GM reductions in overlapping, albeit less widespread, brain regions. Psychosis, a hallmark of SZ, is also experienced by a significant proportion of BD patients and there is evidence that psychotic BD may be characterized by specific clinical and pathophysiological features. However, there are few studies comparing GM between SZ and psychotic BD. In this study we compared GM volumes in a sample of 58 SZ patients, 28 BD patients experiencing psychotic symptoms and 43 healthy controls using whole-brain voxel-based morphometry. SZ patients had GM reductions in multiple frontal and temporal regions compared to healthy controls and in the subgenual cortex compared to psychotic BD patients. GM volume was increased in the right posterior cerebellum in SZ patients compared to controls. However, psychotic BD patients did not show significant GM deficits compared to healthy controls or SZ patients. We conclude that GM abnormality as measured by VBM analysis is less pronounced in psychotic BD compared to SZ. This may be due to disease-specific factors or medications used more commonly in BD.

Molecular genetics of the psychosis phenotype

OBJECTIVE

Relative to recent successes in elucidating the genetic mechanisms associated with complex diseases, including macular degeneration, diabetes mellitus, type 2, heart disease, and cancer, molecular genetic approaches to psychiatric illness have met with more limited success. While factors such as small allelic effects, allelic heterogeneity, and variation in population substructure have received considerable attention in attempt to explain the paucity of significant results in psychiatric genetics, significantly less focus has been directed toward phenotypic factors.

METHOD

Data derived from molecular genetic studies of the psychosis phenotype in patients with a range of psychiatric illnesses are reviewed.

RESULTS

Available data suggest that genes do not respect the boundaries of the current diagnostic system but may confer risk for symptom-based phenotypic variation that traverses those boundaries.

CONCLUSIONS

Molecular genetic studies offer convincing evidence for a relation between genetic variation and symptom-based phenotypic variation within psychiatric illness. These data may provide novel insights into the pathophysiology of schizophrenia and other related disorders. The exploration of relations between genetic variation and symptom variation that traverses traditional diagnostic boundaries may ultimately lead to more refined classification systems that more closely reflect the genetic etiology of psychiatric illness.

Differences in resting-state functional magnetic resonance imaging functional network connectivity between schizophrenia and psychotic bipolar probands and their unaffected first-degree relatives

BACKGROUND

Schizophrenia and bipolar disorder share overlapping symptoms and genetic etiology. Functional brain dysconnectivity is seen in both disorders.

METHODS

We compared 70 schizophrenia and 64 psychotic bipolar probands, their respective unaffected first-degree relatives (n = 70, and n = 52), and 118 healthy subjects, all group age-, gender-, and ethnicity-matched. We used functional network connectivity analysis to measure differential connectivity among 16 functional magnetic resonance imaging resting state networks. First, we examined connectivity differences between probands and control subjects. Next, we probed these dysfunctional connections in relatives for potential endophenotypes. Network connectivity was then correlated with Positive and Negative Syndrome Scale (PANSS) scores to reveal clinical relationships.

RESULTS

Three different network pairs were differentially connected in probands (false-discovery rate corrected q < .05) involving five individual resting-state networks: (A) fronto/occipital, (B) anterior default mode/prefrontal, (C) meso/paralimbic, (D) fronto-temporal/paralimbic, and (E) sensory-motor. One abnormal pair was unique to schizophrenia, (C-E), one unique to bipolar, (C-D), and one (A-B) was shared. Two of these three combinations (A-B, C-E) were also abnormal in bipolar relatives but none was normal in schizophrenia relatives (nonsignificant trend for C-E). The paralimbic circuit (C-D), which uniquely distinguished bipolar probands, contained multiple mood-relevant regions. Network relationship C-D correlated significantly with PANSS negative scores in bipolar probands, and A-B with PANSS positive and general scores in schizophrenia.

CONCLUSIONS

Schizophrenia and psychotic bipolar probands share several abnormal resting state network connections, but there are also unique neural network underpinnings between disorders. We identified specific connections that might also be candidate psychosis endophenotypes.

Genome-wide association analysis of age at onset and psychotic symptoms in bipolar disorder

Genome-wide association studies (GWAS) have identified several susceptibility loci for bipolar disorder (BP), most notably ANK3. However, most of the inherited risk for BP remains unexplained. One reason for the limited success may be the genetic heterogeneity of BP. Clinical sub-phenotypes of BP may identify more etiologically homogeneous subsets of patients, which can be studied with increased power to detect genetic variation. Here, we report on a mega-analysis of two widely studied sub-phenotypes of BP, age at onset and psychotic symptoms, which are familial and clinically significant. We combined data from three GWAS: NIMH Bipolar Disorder Genetic Association Information Network (GAIN-BP), NIMH Bipolar Disorder Genome Study (BiGS), and a German sample. The combined sample consisted of 2,836 BP cases with information on sub-phenotypes and 2,744 controls. Imputation was performed, resulting in 2.3 million SNPs available for analysis. No SNP reached genome-wide significance for either sub-phenotype. In addition, no SNP reached genome-wide significance in a meta-analysis with an independent replication sample. We had 80% power to detect associations with a common SNP at an OR of 1.6 for psychotic symptoms and a mean difference of 1.8 years in age at onset. Age at onset and psychotic symptoms in BP may be influenced by many genes of smaller effect sizes or other variants not measured well by SNP arrays, such as rare alleles.

Psychosocial functioning, familiality, and psychiatric comorbidity in bipolar youth with and without psychotic features

OBJECTIVE

Few studies have examined the correlates of psychosis in children and adolescents with bipolar disorder (BPD). We examined psychiatric comorbidity, familiality, and psychosocial functioning in multiple domains in BPD children and adolescents with and without psychotic features.

METHOD

As part of 2 ongoing family-based studies of children and adolescents with DSM-IV-defined BPD, we compared youth and their families with psychotic symptoms (BPD+P) and without psychotic symptoms (BPD-P). All youth and family members were assessed using indirect and direct structured psychiatric interviews (Kiddie Schedule for Affective Disorders-Epidemiologic Version and DSM-IV Structured Clinical Interview) in a blinded manner. One study was conducted from January 2000 through December 2004, and the other study was conducted from February 1997 through September 2006.

RESULTS

Of the 226 youth with BPD, 33% manifested psychotic symptoms, as defined by the presence of hallucinations or delusions. We found that BPD+P youth had a greater number of BPD episodes (P < .01), more psychiatric hospitalizations (P < .01), and significantly higher rates of psychiatric comorbidity compared to BPD-P youth (all P values < .05). Additionally, a higher percentage of BPD+P youth had a family history of psychosis (P = .01). There was a lower processing speed (P = .03) and lower arithmetic scaled score (P = .04) in BPD+P youth, but no other meaningful differences in cognitive variables were identified between the 2 BPD groups. Psychosis in BPD was also associated with decreased family cohesion (P = .04) and poorer overall global functioning (P < .01).

CONCLUSIONS

In children and adolescents with BPD, those who manifest psychotic features have higher rates of comorbid psychopathology, family history of psychosis, and poorer overall functioning in multiple domains than BPD children without psychosis. Future studies should examine neuroimaging correlates, medication response, and longitudinal course of children and adolescents with BPD who manifest psychosis as part of their clinical picture.

Influence of the serotonin transporter gene polymorphism, cannabis and childhood sexual abuse on phenotype of bipolar disorder: a preliminary study

OBJECTIVE

The gene coding for the 5-HT transporter (5-HTT) is considered as a candidate gene for bipolar disorder, either as a "vulnerability" or as a "modifying the phenotype" gene. Psychotic symptoms occur at least once in one bipolar patient out of two, the relevant risk factors being insufficiently understood. The gene × environment interaction approach offers the opportunity to disentangle the latter, including childhood sexual abuse and cannabis abuse.

METHODS

We investigated the 5-HTTLPR of the 5-HTT gene (G) and the presence of childhood sexual abuse and cannabis comorbidity (E) in 137 bipolar patients with (versus without) lifetime psychotic symptoms.

RESULTS

The short allele and cannabis abuse were significantly more frequent among patients with psychotic symptoms than in those without (p=0.01 and p=0.004, respectively), while childhood sexual abuse was not. Complex interactions were found between presence of the short allele, cannabis abuse or dependence and childhood sexual abuse.

CONCLUSIONS

The short allele of the 5-HTTLPR polymorphism of the 5-HTT gene was a risk factor for psychotic symptoms in bipolar disorder in the present sample, directly but also indirectly, through the presence of cannabis abuse or dependence, as an exacerbating factor heightening psychotic symptoms.

Neurocognitive markers of psychosis in bipolar disorder: a meta-analytic study

BACKGROUND

It has been suggested that patients with psychotic bipolar disorder (BDP+) might have more severe cognitive deficits than non-psychotic bipolar disorder patients (BDP-). However, only a handful of studies have compared cognition between BDP+ and BDP-. Our aim was to examine cognitive deficits associated with psychosis in BD using meta-analytic methods.

METHODS

After a systematic literature review, we conducted a meta-analysis on studies that compared cognition in bipolar disorder (BD) patients with and without a history of psychosis. In addition the effects of clinical and demographic confounder factors were examined with meta-regression analyses.

RESULTS

There were no significant differences for gender and duration of illness between groups. Compared with BDP-, BDP+ patients had more inpatient admissions, a younger onset of illness and used antipsychotics more commonly. BDP+ patients also performed significantly worse in 4 of 6 cognitive domains (planning and reasoning, working memory, verbal memory and processing speed). There were also differences for some individual tasks (List Learning, Delayed Recall, Trail Making B, Wisconsin Card Sorting Test, Digits Backwards, Stroop Interference, Semantic Fluency) with BDP+ patients showing moderately greater impairment on these tasks (d=0.30-0.55).

CONCLUSIONS

A history of psychosis is associated with greater severity of cognitive deficits in BD. However, this effect is modest, and these findings do not suggest a complete categorical distinction between BDP+ and BDP-. Psychosis in BD might reflect partly distinct neurobiological processes.

Psychotic versus non-psychotic bipolar II disorder

INTRODUCTION

Psychotic symptoms in bipolar II disorder, allowed by definition only during a depressive episode, are present in a range between 3% and 45%. Little is known regarding the impact of psychotic symptoms on the clinical course of bipolar II patients. Findings from previous reports are controversial and focused specifically on bipolar I disorder. The aim of this study was to ascertain the clinical characteristics of individuals with bipolar II disorder with and without lifetime history of psychotic symptoms.

METHODS

The sample consisted of 164 DSM-IV Bipolar II patients consecutively recruited from the Barcelona Bipolar Disorder Program. Patients were divided in Bipolar II patients with (N=32) and without (N=132) lifetime history of psychotic symptoms. Clinical and sociodemographic features were compared.

RESULTS

Thirty-two out of 164 patients with bipolar II disorder had a history of psychosis during depression (19.5%). Bipolar II patients with a history of psychotic symptoms showed a higher number of hospitalizations than patients without such a history (p<0.001). They were also older but were less likely to have a family history of bipolar illness and any mental disorder than non-psychotic bipolar II patients. Melancholic and catatonic features were significantly more frequent in psychotic bipolar II patients (p<0.001).

CONCLUSIONS

Our findings confirm that the presence of psychotic symptoms in bipolar II disorder is not rare. Psychotic bipolar II disorder may be a different phenotype from non-psychotic bipolar disorder.

Genetics and intermediate phenotypes of the schizophrenia--bipolar disorder boundary

Categorization of psychotic illnesses into schizophrenic and affective psychoses remains an ongoing controversy. Although Kraepelinian subtyping of psychosis was historically beneficial, modern genetic and neurophysiological studies do not support dichotomous conceptualization of psychosis. Evidence suggests that schizophrenia and bipolar disorder rather present a clinical continuum with partially overlapping symptom dimensions, neurophysiology, genetics and treatment responses. Recent large scale genetic studies have produced inconsistent findings and exposed an urgent need for re-thinking phenomenology-based approach in psychiatric research. Epidemiological, linkage and molecular genetic studies, as well as studies in intermediate phenotypes (neurocognitive, neurophysiological and anatomical imaging) in schizophrenia and bipolar disorders are reviewed in order to support a dimensional conceptualization of psychosis. Overlapping and unique genetic and intermediate phenotypic signatures of the two psychoses are comprehensively recapitulated. Alternative strategies which may be implicated into genetic research are discussed.

Stroop and emotional Stroop interference in unaffected relatives of patients with schizophrenic and bipolar disorders: distinct markers of vulnerability?

Reduced inhibition has been demonstrated in both schizophrenic and bipolar patients through the findings of increased interference on the Stroop Colour-Word Task (SCWT) and increased emotional interference on specific versions of the Emotional Stroop Task (EST). Despite previous findings of enhanced interference in unaffected relatives of schizophrenic and bipolar patients, it remains unclear whether interference might be a candidate endophenotype to both disorders. Moreover, data regarding emotional interference in unaffected relatives are critically lacking. In the present study, we aimed to compare unaffected relatives of patients with schizophrenia (SZ-rel, N = 30) and bipolar disorder (BD-rel, N= 30) with normal controls (N = 60) when performing the SCWT and an EST designed with neutral, depressive, paranoid and manic words. SZ-rel exhibited greater interference effect on both the SCWT and the EST as compared to either BD-rel or normal controls. BD-rel, and by contrast to SZ-rel and controls, showed increased emotional interference effect on the EST that was specifically associated to the disease-related words. The findings support the hypothesis of different markers of vulnerability to schizophrenic and bipolar disorders; impairment in cognitive inhibition could characterize high-risk individuals for schizophrenia whereas an emotional bias towards mood-related information could be a trait marker of bipolar disease.

The psychoses: cluster 3 of the proposed meta-structure for DSM-V and ICD-11

BACKGROUND

In an effort to group mental disorders on the basis of etiology, five clusters have been proposed. Here we consider the validity of the cluster comprising selected psychotic and related disorders.

METHOD

A group of diagnostic entities classified under schizophrenia and other psychotic disorders in DSM-IV-TR were assigned to this cluster and the bordering disorders, bipolar (BD) and schizotypal personality disorders (SPD), were included. We then reviewed the literature in relation to 11 validating criteria proposed by the DSM-V Task Force Study Group.

RESULTS

Relevant comparisons on the 11 spectrum criteria are rare for the included disorders except for schizophrenia and the two border conditions, BD and SPD. The core psychosis group is congruent at the level of shared psychotic psychopathology and response to antipsychotic medication. BD and SPD are exceptions in that psychosis is not typical in BD-II disorder and frank psychosis is excluded in SPD. There is modest similarity between schizophrenia and BD relating to risk factors, neural substrates, cognition and endophenotypes, but key differences are noted. There is greater support for a spectrum relationship of SPD and schizophrenia. Antecedent temperament, an important validator for other groupings, has received little empirical study in the various psychotic disorders.

CONCLUSIONS

The DSM-IV-TR grouping of psychotic disorders is supported by tradition and shared psychopathology, but few data exist across these diagnoses relating to the 11 spectrum criteria. The case for including BD is modest, and the relationship of BD to other mood disorders is addressed elsewhere. Evidence is stronger for inclusion of SPD, but the relationship with other personality disorders along the 11 criteria is not addressed and the absence of psychosis presents a conceptual problem. There are no data along the 11 spectrum criteria that are decisive for a cluster based on etiology, and inclusion of BD and SPD is questionable.

Mood-incongruent psychosis in bipolar disorder: conditional linkage analysis shows genome-wide suggestive linkage at 1q32.3, 7p13 and 20q13.31

OBJECTIVE

The majority of research into functional psychosis has proceeded under the assumption that schizophrenia and bipolar disorder are distinct entities with separate underlying disease processes and treatments. This view has been increasingly challenged in both clinical and genetic studies. Findings in recent association studies at two specific genes suggest that the occurrence of mood-incongruent psychotic features may indicate a relatively homogeneous subset of the bipolar phenotype. We examined this hypothesis.

METHODS

Caucasian affected individuals were ascertained from Europe (the United Kingdom, the Republic of Ireland, Germany, Italy and Andalusia). Consensus best-estimate diagnoses were assigned by two independent raters according to all available information. There was no cross-site evaluation of inter-rater reliability. Families multiply affected by bipolar spectrum mood disorder were selected, comprising 383 affected relative pairs. Individuals were considered to be affected if they were diagnosed with DSM-IV bipolar I disorder or schizoaffective disorder, bipolar type. Multipoint, affected relative pair covariate linkage analysis was performed.

RESULTS

Significant familiality of incongruent psychosis was observed [intra-class correlation coefficient (ICC) = 0.309; p = 0.001, one-tail]. Covariate linkage analysis provided three regions with genome-wide suggestive evidence for linkage on chromosomes 1q32.3 (LOD = 4.15, expected 0.12 times per genome scan), 7p13 (LOD = 3.32) and 20q13.31 (LOD = 2.98). No region in our analysis met criteria for genome-wide significance.

CONCLUSION

Our results provide molecular support for the hypothesis that genes may exist for specific forms of bipolar illness, dependent on the presence or absence of incongruent psychosis. Our findings suggest that researchers should take account of mood-congruence/incongruence of psychotic features in studies of bipolar disorder.

Adjunctive topiramate treatment for a refractory familial adolescent mania

Adolescent mania is often misdiagnosed. This case study describes the clinical course and diagnostic reclassification from schizophrenia to bipolar disorder in a 15-year-old girl. This case study also describes the pedigree of the siblings, familial aggregation, and anticipation of mood disorders. In addition, we present the successful use of topiramate, a new antiepileptic drug, which is increasingly being used as a mood stabilizer in paediatric bipolar disorder. The efficacy of topiramate in this case supports its role as a promising agent in treatment-resistant adolescent mania associated with familial aggregation.

Will the Kraepelinian dichotomy survive DSM-V?

Kraepelin proposed dementia praecox and manic-depressive illness as the two major psychotic disorders. This paradigm is still prevalent, but observations of overlapping boundaries between bipolar disorder and schizophrenia challenge this dichotomy. However, the concept of schizophrenia has been radically altered from the original Kraepelinian proposal. We defend the two psychoses positions, but suggest two flaws in the heuristic application: (1) overlapping features, such as psychotic symptoms, are not decisive in differential diagnosis; and (2) each disorder is a syndrome, not a disease entity. An alternative paradigm based on domains of pathology is more powerful for studies of etiology, pathophysiology, and therapeutic discovery.

Theory of mind deficit in bipolar disorder: is it related to a previous history of psychotic symptoms?

It has been hypothesized that a Theory of Mind (ToM) deficit could be a vulnerability marker for psychosis. Recent studies, however, have shown ToM deficits in affective relapses of bipolar disorder as well as in the euthymic phase. This study analyzes the relationship between ToM and a previous history of psychotic symptoms in bipolar disorder. ToM, sustained attention and executive functions were analyzed in 75 bipolar euthymic patients with three or more previous relapses (42 of them had a history of psychotic symptoms and 33 did not) and 48 healthy subjects. ToM was assessed with the Advanced Test by Happé. ToM performance was similar in bipolar patients with or without a history of psychotic symptoms, and in both cases it was significantly reduced as compared with the healthy control group. Similarly, both bipolar groups showed impaired sustained attention and executive functions. This general cognitive deficit partially explains the differences obtained in ToM. The ToM instrument used shows low sensitivity for assessing ToM in bipolar patients and it could partially reflect general cognitive functioning rather than a specific deficit in psychosis. ToM deficit is not a trait marker for psychosis, given that it is present in bipolar disorder regardless of a previous history of psychotic symptoms.

The genetics of symptom-based phenotypes: toward a molecular classification of schizophrenia

OBJECTIVE

Genetic linkage studies in schizophrenia (SZ) have primarily focused on the phenotype of disease susceptibility. A limited number of studies, however, have reported suggestive linkage to specific SZ symptom domains including regions on chromosomes 6, 8, and 20. We examined these chromosomal regions for association to positive, negative, and disorganized symptom clusters, using a dense set of single-nucleotide polymorphisms (SNPs).

METHODS

We ascertained 178 Caucasian patients with SZ for lifetime severity of clinical symptomatology using a structured diagnostic interview. The cohort was genotyped with the Affymetrix 500K microarray, from which we selected, a priori, 4833 intragenic SNPs located within chromosomal regions previously linked to specific SZ symptom clusters. Parametric tests, corrected for multiple testing, were used to compare the effects of allelic variation within these SNPs to the lifetime severity of the specific symptom domain that had been implicated by prior linkage studies.

RESULTS

We were able to extend previous reports of linkage between chromosome 6q and both positive and disorganized symptoms. Lifetime severity of positive symptoms was significantly (P = 2.50 x 10(-5)) associated with a SNP within the origin recognition complex subunit 3-like (ORC3L) gene, a gene implicated in synaptic plasticity. Level of disorganized symptoms was significantly (P < 6.00 x 10(-5)) associated 2 SNPs within the brain-specific angiogenesis inhibitor 3 (BAI3) gene, which is highly expressed in brain during development.

CONCLUSIONS

These data point toward specific candidate genes located within previously implicated linkage peaks for clinical symptomatology. Identification of functional variants within these regions and a characterization of the effect of these risk genotypes on the treatment of specific clinical symptoms are needed.

Association study of Wnt signaling pathway genes in bipolar disorder

CONTEXT

The Wnt signaling pathways promote cell growth and are best known for their role in embryogenesis and cancer. Several lines of evidence suggest that these pathways might also be involved in bipolar disorder.

OBJECTIVE

To test for an association between candidate genes in the Wnt signaling pathways and disease susceptibility in a family-based bipolar disorder study.

DESIGN

Two hundred twenty-seven tagging single- nucleotide polymorphisms (SNPs) from 34 genes were successfully genotyped. Initial results led us to focus on the gene PPARD, in which we genotyped an additional 13 SNPs for follow-up.

SETTING

Nine academic medical centers in the United States.

PARTICIPANTS

Five hundred fifty-four offspring with bipolar disorder and their parents from 317 families.

MAIN OUTCOME MEASURES

Family-based association using FBAT and HBAT (http://www.biostat.harvard.edu/~fbat/default.html; Harvard School of Public Health, Boston, Massachusetts). Exploratory analyses testing for interactions of PPARD SNPs with clinical covariates and with other Wnt genes were conducted with GENASSOC (Stata Corp, College Station, Texas).

RESULTS

In the initial analysis, the most significantly associated SNP was rs2267665 in PPARD (nominal P < .001). This remained significant at P = .05 by permutation after accounting for all SNPs tested. Additional genotyping in PPARD yielded 4 SNPs in 1 haplotype block that were significantly associated with bipolar disorder (P < .01), the most significant being rs9462082 (P < .001). Exploratory analyses revealed significant evidence (P < .01) for interactions of rs9462082 with poor functioning on the Global Assessment Scale (odds ratio [OR], 3.36; 95% confidence interval [CI], 1.85-6.08) and with SNPs in WNT2B (rs3790606: OR, 2.56; 95% CI, 1.67-4.00) and WNT7A (rs4685048: OR, 1.79; 95% CI, 1.23-2.63).

CONCLUSIONS

We found evidence for association of bipolar disorder with PPARD, a gene in the Wnt signaling pathway. The consistency of this result with one from the Wellcome Trust Case-Control Consortium encourages further study. If the finding can be confirmed in additional samples, it may illuminate a new avenue for understanding the pathogenesis of severe bipolar disorder and developing more effective treatments.

Neurocognitive allied phenotypes for schizophrenia and bipolar disorder

Psychiatric disorders are genetically complex and represent the end product of multiple biological and social factors. Links between genes and disorder-related abnormalities can be effectively captured via assessment of phenotypes that are both associated with genetic effects and potentially contributory to behavioral abnormalities. Identifying intermediate or allied phenotypes as a strategy for clarifying genetic contributions to disorders has been successful in other areas of medicine and is a promising strategy for identifying susceptibility genes in complex psychiatric disorders. There is growing evidence that schizophrenia and bipolar disorder, rather than being wholly distinct disorders, share genetic risk at several loci. Further, there is growing evidence of similarity in the pattern of cognitive and neurobiological deficits in these groups, which may be the result of the effects of these common genetic factors. This review was undertaken to identify patterns of performance on neurocognitive and affective tasks across probands with schizophrenia and bipolar disorder as well as unaffected family members, which warrant further investigation as potential intermediate trait markers. Available evidence indicates that measures of attention regulation, working memory, episodic memory, and emotion processing offer potential for identifying shared and illness-specific allied neurocognitive phenotypes for schizophrenia and bipolar disorder. However, very few studies have evaluated neurocognitive dimensions in bipolar probands or their unaffected relatives, and much work in this area is needed.

Rapid switching of mood in families with familial bipolar disorder

OBJECTIVE

Rapid switching of moods in bipolar disorder has been associated with early age at onset, panic comorbidity, and suicidality. This study aims to confirm these associations and investigate other potential correlates of rapid switching of mood using families from a multisite bipolar linkage study.

METHODS

The subjects were comprised of 1,143 probands and relatives with diagnosis of bipolar disorder. All subjects were interviewed directly with a standard diagnostic instrument, and all subjects who met criteria for bipolar disorder were asked if their moods had ever switched rapidly.

RESULTS

Individuals with rapid mood switching had significantly earlier age at onset (18 versus 21 years, p < 0.00001), higher comorbid anxiety (47% versus 26%, p < 0.00001) and substance use disorders (52% versus 42%, p = 0.0006), higher rate of violent behavior (6% versus 3%, p < 0.004), suicidal behavior (46% versus 31%, p < 0.00001), and nonsuicidal self-harm (13% versus 6%, p < 0.0002). Multiple logistic regression analysis found significant net effects on rapid mood switching for early emergence of symptoms [odds ratio (OR) = 0.62; 95% confidence interval (CI): 0.45-0.85]; anxiety comorbidity (OR = 2.31; 95% CI: 1.34-3.98); and hypersensitivity to antidepressants (OR = 2.05; 95% CI: 1.49-2.83) as the strongest predictors.

CONCLUSIONS

This confirms earlier reports associating rapid switching with a more complex clinical course, in particular early emergence of bipolar symptomatology, antidepressant activation, and anxiety comorbidity. These results support a clinical differentiation of bipolar disorder into subtypes based on symptom stability.