Lateral ventricle differences between first-episode schizophrenia and first-episode psychotic bipolar disorder: A population-based morphometric MRI study

Abstract

Objectives. The extent to which psychotic disorders fall into distinct diagnostic categories or can be regarded as lying on a single continuum is controversial. We compared lateral ventricle volumes between a large sample of patients with first-episode schizophrenia or bipolar disorder and a healthy control group from the same neighbourhood. Methods. Population-based MRI study with 88 first-episode psychosis (FEP) patients, grouped into those with schizophrenia/schizophreniform disorder (N=62), bipolar disorder (N=26) and 94 controls. Results. Right and left lateral ventricular and right temporal horn volumes were larger in FEP subjects than controls. Within the FEP sample, post-hoc tests revealed larger left lateral ventricles and larger right and left temporal horns in schizophrenia subjects relative to controls, while there was no difference between patients with bipolar disorder and controls. None of the findings was attributable to effects of antipsychotics. Conclusions. This large-sample population-based MRI study showed that neuroanatomical abnormalities in subjects with schizophrenia relative to controls from the same neighbourhood are evident at the first episode of illness, but are not detectable in bipolar disorder patients. These data are consistent with a model of psychosis in which early brain insults of neurodevelopmental origin are more relevant to schizophrenia than to bipolar disorder.     

An MRI study of temporal lobe structures in men with bipolar disorder or schizophrenia.

BACKGROUND: Hippocampal atrophy has been described in postmortem and magnetic resonance imaging studies of schizophrenia. The specificity of this finding to schizophrenia remains to be determined. The neuropathology of bipolar disorder is understudied, and temporal lobe structures have only recently been evaluated. METHODS: Twenty-four bipolar, 20 schizophrenic, and 18 normal comparison subjects were evaluated using magnetic resonance brain imaging. Image data were acquired using a three-dimensional spoiled GRASS sequence, and brain images were reformatted in three planes. Temporal lobe structures including the amygdala, hippocampus, parahippocampus, and total temporal lobe were measured to obtain volumes for each structure in the three subject groups. Severity of symptoms in both patient groups was assessed at the time the magnetic resonance images were obtained. RESULTS: Hippocampal volumes were significantly smaller in the schizophrenic group than in both bipolar and normal comparison subjects. Further, amygdala volumes were significantly larger in the bipolar group than in both schizophrenic and normal comparison subjects. CONCLUSIONS: The results suggest differences in affected limbic structures in patients with schizophrenia and bipolar disorder. These specific neuroanatomic abnormalities may shed light on the underlying pathophysiology and presentation of the two disorders.     

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.     

A family study of psychotic symptomatology in schizophrenia,schizoaffective disorder,unipolar depression,and bipolar disorder

Summary An evaluation was made of schizophrenics (140), schizoaffectives (40), unipolar depressives (59), and bipolars (30), and their relatives who had a chart diagnosis of psychosis or depressive neurosis. The purpose was to determine whether the psychosis (delusions and hallucinations) was transmitted independently of the illness itself. If this were true, there would be an excess of pairs of probands and relatives both positive for psychosis and pairs of relatives and probands both negative for psychosis when compared to relatives and probands who were not concordant for the variable. This was found to be true in schizophrenia and schizoaffective disorder and is probably the result of the simple transmission of an illness which includes the presence of psychotic symptoms in the definition. Thus, this would be a manifestation of the genetic propensity in schizophrenia. For the affective disorders there was no evidence that psychotic probands were more likely than the nonpsychotic to have psychotic relatives. So far the reason why some patients have psychosis and others not in the affective disorders remains unexplained.     

Clozapine for treatment-refractory schizophrenia, schizoaffective disorder, and psychotic bipolar disorder: a 24-month naturalistic study

BACKGROUND: The aim of this study was to evaluate the 24-month response to clozapine in patients with schizophrenia, schizoaffective disorder, or psychotic bipolar disorder. METHOD: Ninety-one psychotic patients with a principal DSM-III-R diagnosis of schizophrenia (N = 31), schizoaffective disorder (N = 26), or bipolar disorder with psychotic features (N = 34) were treated naturalistically with clozapine at flexible dosages over a 24-month period. Improvement was assessed by the 18-item Brief Psychiatric Rating Scale and the Clinical Global Impressions-Severity of Illness scale. RESULTS: All patients showed significant improvement 24 months from intake (p < .001). Such an improvement was significantly greater among patients with schizoaffective disorder or bipolar disorder than in patients with schizophrenia (p < .05). The presence of suicidal ideation at intake predicted greater improvement at endpoint. CONCLUSION: Clozapine appears to be effective and relatively well tolerated in acute and long-term treatment of patients with psychotic bipolar disorder or schizoaffective disorder who have not responded to conventional pharmacotherapies.     

An emotional Stroop functional MRI study of euthymic bipolar disorder

Objective:  To identify the brain regions associated with emotional processing in euthymic bipolar patients.
Methods:  The study examined 12 euthymic bipolar patients using functional magnetic resonance imaging (fMRI) while performing an emotional Stroop (eStroop) task. The task comprised emotionally valent and neutral words presented in alternating blocks that was designed to implicitly induce affect. In conjunction with fMRI, galvanic skin responses (GSR) were measured to monitor arousal.
Results:  Euthymic bipolar patients had diminished activation in response to the affective stimuli in both cortical and subcortical brain regions when compared with healthy subjects. In particular, patients had less activation in the left ventral prefrontal cortex suggesting a potential trait deficit. Patients were slower to react than healthy controls, but did not differ with respect to accuracy.
Conclusions:  Euthymic bipolar patients are perhaps constrained in their ability to engage affective processing. Diminished ventral prefrontal cortex activation corroborates previous reports of a potential trait deficit, suggesting that 'all is not well in euthymia', although the effects of medication cannot be overlooked.     

Relational memory in psychotic bipolar disorder

Sheffield JM, Williams LE, Cohen N, Heckers S. Relational memory in psychotic bipolar disorder.
Bipolar Disord 2012: 14: 537–546. © 2012 The Authors. Journal compilation © 2012 John Wiley & Sons A/S. 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.     

Insight and neuropsychological function in patients with schizophrenia and bipolar disorder with psychotic features.

OBJECTIVES: This study investigates the pattern of association between patient unawareness of illness and neuropsychological tests of frontal lobe function in subjects with schizophrenia and bipolar disorder (BD) with psychotic features. METHOD: We administered the Wisconsin Card Sort Test (WCST) and a shortened version of the Scale to Assess Unawareness of Mental Disorder (SUMD) to a sample of 64 patients with psychosis (42 with schizophrenia and 22 with BD). RESULTS: None of the correlations between WCST scores and insight scores were statistically significant, either in the total group or in each group analyzed separately. Further, no differences were seen in insight scores between sexes and between the diagnostic groups. CONCLUSIONS: The 3 insight dimensions (that is, awareness of mental disorder, awareness of social consequences of mental disorder, and awareness of the benefits of medication) do not appear to be associated with frontal impairment, as measured by the WCST.     

Aggrecan and chondroitin-6-sulfate abnormalities in schizophrenia and bipolar disorder: a postmortem study on the amygdala

Perineuronal nets (PNNs) are specialized extracellular matrix aggregates surrounding distinct neuronal populations and regulating synaptic functions and plasticity. Previous findings showed robust PNN decreases in amygdala, entorhinal cortex and prefrontal cortex of subjects with schizophrenia (SZ), but not bipolar disorder (BD). These studies were carried out using a chondroitin sulfate proteoglycan (CSPG) lectin marker. Here, we tested the hypothesis that the CSPG aggrecan, and 6-sulfated chondroitin sulfate (CS-6) chains highly represented in aggrecan, may contribute to these abnormalities. Antibodies against aggrecan and CS-6 (3B3 and CS56) were used in the amygdala of healthy control, SZ and BD subjects. In controls, aggrecan immunoreactivity (IR) was observed in PNNs and glial cells. Antibody 3B3, but not CS56, also labeled PNNs in the amygdala. In addition, dense clusters of CS56 and 3B3 IR encompassed CS56- and 3B3-IR glia, respectively. In SZ, numbers of aggrecan- and 3B3-IR PNNs were decreased, together with marked reductions of aggrecan-IR glial cells and CS-6 (3B3 and CS56)-IR ‘clusters''. In BD, numbers of 3B3-IR PNNs and CS56-IR clusters were reduced. Our findings show disruption of multiple PNN populations in the amygdala of SZ and, more modestly, BD. Decreases of aggrecan-IR glia and CS-6-IR glial ‘clusters'', in sharp contrast to increases of CSPG/lectin-positive glia previously observed, indicate that CSPG abnormalities may affect distinct glial cell populations and suggest a potential mechanism for PNN decreases. Together, these abnormalities may contribute to a destabilization of synaptic connectivity and regulation of neuronal functions in the amygdala of subjects with major psychoses.     

An event-related functional MRI study of working memory in euthymic bipolar disorder

OBJECTIVE: Bipolar disorder (BD) is emerging as an illness marred by neurocognitive deficits, many of which do not resolve on recovery. Deficits affecting working memory (WM) in particular appear to be significant. WM comprises temporally separated biological processes that involve the on-line retention and manipulation of information. Previous neuroimaging studies have not sought to dissect the individual contributions of WM and examined WM subprocesses in euthymic BD. In this study, we investigated the encode, delay and response components of WM to identify the neural substrates and respective contributions to the WM deficits found in BD. METHODS: We used event-related functional magnetic resonance imaging and a parametric WM task, incorporating 3 load conditions, to delineate individual WM subprocesses in 10 euthymic BD patients and 10 control subjects. RESULTS: Patients exhibited attenuated patterns of activity, predominantly in frontal brain regions, across all WM components. CONCLUSIONS: Based on the attenuated activity observed in the patients, the clinical deficits in WM found in BD may reflect broad fronto-cortico-limbic dysfunction that is not confined to any single WM component. This is important in understanding the pathophysiology of BD and for future studies on executive functions in patients with this illness.     

The genetics of psychotic bipolar disorder

Psychotic features, defined as delusions or hallucinations, commonly occur in bipolar disorder (BP) and may be indicative of a more homogeneous form of the illness, with possible etiologic ties to schizophrenia. Several studies have shown that psychotic features aggregate in bipolar families, and increased interest in the molecular genetics of psychotic BP is emerging. Although preliminary, linkage studies of psychotic BP show replicated evidence for suggestive genome-wide linkage to chromosomes 8p and 13q, which have been implicated in prior linkage studies of schizophrenia and BP. Association studies of psychotic BP and sub-types such as mood-incongruent psychotic BP have uncovered modest positive results for several candidate schizophrenia susceptibility genes, including dysbindin, DAOA/G30, Disrupted-in-Schizophrenia-1, and neuregulin 1. These tentative results are consistent with the hypothesis that the subphenotype of psychotic BP may represent a clinical manifestation of “overlap” genes between schizophrenia and mood disorder syndromes.     

Clozapine in treatment-resistant patients with schizophrenia,schizoaffective disorder,or psychotic bipolar disorder: a naturalistic 48-month follow-up study

BACKGROUND: The aim of this study was to evaluate the long-term efficacy and safety of clozapine in patients with treatment-resistant schizophrenia, schizoaffective disorder, or bipolar disorder with psychotic features. METHOD: 101 patients with a DSM-III-R diagnosis of schizophrenia (N = 34); schizoaffective disorder, bipolar type (N = 30); or bipolar disorder with psychotic features (N = 37) were naturalistically treated with clozapine at flexible doses over a 48-month period. Data were collected from 1994 to 2000. The Brief Psychiatric Rating Scale (BPRS) and Clinical Global Impressions-Severity of Illness scale total predicted scores over time were estimated with random-effects regression models. Time to response to clozapine, defined as 50% reduction of BPRS score, was analyzed in the 3 diagnostic groups using the Kaplan-Meier method. Survival curves were compared using the log-rank test. RESULTS: The BPRS total predicted score halved its baseline value in 3 months for bipolar disorder patients, in 6 months for schizoaffective disorder patients, and in 24 months for schizophrenia patients. The proportion of subjects who satisfied the criterion for response to clozapine after 48 months of follow-up was significantly (p <.01) higher in the schizoaffective and bipolar disorder groups (90.0% and 83.8%, respectively) than in the schizophrenia group (64.7%). Baseline scores on the Global Assessment of Functioning (GAF) showed low levels of psychosocial and occupational functioning in all 3 groups. After 48 months of treatment, GAF scores showed a functional improvement in all 3 groups, with significantly (p <.01) greater improvement in the bipolar disorder group compared with the other groups. CONCLUSION: The findings of this study confirm the efficacy and safety of clozapine for treatment-resistant patients with a diagnosis of schizophrenia, schizoaffective disorder, or bipolar disorder with psychotic features. Patients with schizoaffective disorder and those with bipolar disorder show greater clinical improvement than those with schizophrenia. Patients with bipolar disorder have the shortest time to response and the highest psychosocial and occupational functioning levels. Patients with schizoaffective disorder have the lowest treatment discontinuation rate.     

Differential impairment of social cognition factors in bipolar disorder with and without psychotic features and schizophrenia

While it is well-established that patients with schizophrenia and bipolar disorder exhibit deficits in social cognition, few studies have separately examined bipolar disorder with and without psychotic features. The current study addressed this gap by comparing patients with bipolar disorder with (BD+) and without (BD–) psychotic features, patients with schizophrenia (SZ), and healthy controls (NC) across social cognitive measures. Principal factor analysis on five social cognition tasks extracted a two-factor structure comprised of social/emotional processing and theory of mind. Factor scores were compared among the four groups. Results identified differential patterns of impairment between the BD+ and BD– group on the social/emotional processing factor while all clinical groups performed poorer than controls on the theory of mind factor. This provides evidence that a history of psychosis should be taken into account while evaluating social cognition in patients with bipolar disorder and also raises hypotheses about the relationship between social cognition and psychosis.     

An MRI study of adolescent patients with either schizophrenia or bipolar disorder as compared to healthy control subjects.

BACKGROUND: There are few imaging studies in adolescent patients with either schizophrenia or bipolar disorder. Such studies are of interest because adolescents may have a more severe illness and neurodevelopmental events may have a greater role in their pathophysiology. METHODS: We compared 20 patients with schizophrenia and 15 patients with bipolar disorder (10 to 18 years) to 16 normal adolescents on magnetic resonance imaging (MRI) measures of intracranial volume and ventricular and sulcal enlargement. Two planned comparison contrasts were employed, one comparing the two patient groups to each other (contrast 1), and one comparing both patient groups combined to control subjects (contrast 2). RESULTS: None of the contrast 1 comparisons (schizophrenia vs bipolar) were statistically significant. Contrast 2 comparisons (control subjects vs patients) were statistically significant for intracranial volume (reduced in patients) as well as frontal and temporal sulcal size (increased in patients). CONCLUSIONS: The patient groups were not statistically significantly different from each other on any measure. The combined patient groups were different from control subjects on intracranial volume and frontal and temporal sulcal size. Also, there was evidence for ventricular enlargement, after removal of a control subject with an extreme value. These findings indicate that the same abnormalities noted in adult populations are present in adolescents.