The Maudsley Early Onset Schizophrenia Study: The effect of age of onset and illness duration on fronto-parietal gray matter

Objective

In Early Onset Schizophrenia (EOS; onset before the 18th birthday) late brain maturational changes may interact with disease mechanisms leading to a wave of back to front structural changes during adolescence. To further explore this effect we examined the relationship between age of onset and duration of illness on brain morphology in adolescents with EOS.

Subjects and methods

Structural brain magnetic resonance imaging scans were obtained from 40 adolescents with EOS. We used Voxel Based Morphometry and multiple regressions analyses, implemented in SPM, to examine the relationship between gray matter volume with age of onset and illness duration.

Results

Age of onset showed a positive correlation with regional gray matter volume in the right superior parietal lobule (Brodmann Area 7). Duration of illness was inversely related to regional gray matter volume in the left inferior frontal gyrus (BA 11/47).

Conclusions

Parietal gray matter loss may contribute to the onset of schizophrenia while orbitofrontal gray matter loss is associated with illness duration.

Examination of the predictive value of structural magnetic resonance scans in bipolar disorder: a pattern classification approach

BACKGROUND

Bipolar disorder (BD) is one of the leading causes of disability worldwide. Patients are further disadvantaged by delays in accurate diagnosis ranging between 5 and 10 years. We applied Gaussian process classifiers (GPCs) to structural magnetic resonance imaging (sMRI) data to evaluate the feasibility of using pattern recognition techniques for the diagnostic classification of patients with BD.

METHOD

GPCs were applied to gray (GM) and white matter (WM) sMRI data derived from two independent samples of patients with BD (cohort 1: n = 26; cohort 2: n = 14). Within each cohort patients were matched on age, sex and IQ to an equal number of healthy controls.

RESULTS

The diagnostic accuracy of the GPC for GM was 73% in cohort 1 and 72% in cohort 2; the sensitivity and specificity of the GM classification were respectively 69% and 77% in cohort 1 and 64% and 99% in cohort 2. The diagnostic accuracy of the GPC for WM was 69% in cohort 1 and 78% in cohort 2; the sensitivity and specificity of the WM classification were both 69% in cohort 1 and 71% and 86% respectively in cohort 2. In both samples, GM and WM clusters discriminating between patients and controls were localized within cortical and subcortical structures implicated in BD.

CONCLUSIONS

Our results demonstrate the predictive value of neuroanatomical data in discriminating patients with BD from healthy individuals. The overlap between discriminative networks and regions implicated in the pathophysiology of BD supports the biological plausibility of the classifiers.

Increased salience of gains versus decreased associative learning differentiate bipolar disorder from schizophrenia during incentive decision making

BACKGROUND

Abnormalities in incentive decision making, typically assessed using the Iowa Gambling Task (IGT), have been reported in both schizophrenia (SZ) and bipolar disorder (BD). We applied the Expectancy-Valence (E-V) model to determine whether motivational, cognitive and response selection component processes of IGT performance are differentially affected in SZ and BD.

METHOD

Performance on the IGT was assessed in 280 individuals comprising 70 remitted patients with SZ, 70 remitted patients with BD and 140 age-, sex- and IQ-matched healthy individuals. Based on the E-V model, we extracted three parameters, 'attention to gains or loses', 'expectancy learning' and 'response consistency', that respectively reflect motivational, cognitive and response selection influences on IGT performance.

RESULTS

Both patient groups underperformed in the IGT compared to healthy individuals. However, the source of these deficits was diagnosis specific. Associative learning underlying the representation of expectancies was disrupted in SZ whereas BD was associated with increased incentive salience of gains. These findings were not attributable to non-specific effects of sex, IQ, psychopathology or medication.

CONCLUSIONS

Our results point to dissociable processes underlying abnormal incentive decision making in BD and SZ that could potentially be mapped to different neural circuits.

The impact of the Val158Met catechol-O-methyltransferase genotype on neural correlates of sad facial affect processing in patients with bipolar disorder and their relatives

BACKGROUND

The Met allele of the catechol-O-methyltransferase (COMT) valine-to-methionine (Val158Met) polymorphism is known to affect dopamine-dependent affective regulation within amygdala-prefrontal cortical (PFC) networks. It is also thought to increase the risk of a number of disorders characterized by affective morbidity including bipolar disorder (BD), major depressive disorder (MDD) and anxiety disorders. The disease risk conferred is small, suggesting that this polymorphism represents a modifier locus. Therefore our aim was to investigate how the COMT Val158Met may contribute to phenotypic variation in clinical diagnosis using sad facial affect processing as a probe for its neural action.

METHOD

We employed functional magnetic resonance imaging to measure activation in the amygdala, ventromedial PFC (vmPFC) and ventrolateral PFC (vlPFC) during sad facial affect processing in family members with BD (n=40), MDD and anxiety disorders (n=22) or no psychiatric diagnosis (n=25) and 50 healthy controls.

RESULTS

Irrespective of clinical phenotype, the Val158 allele was associated with greater amygdala activation and the Met158 allele with greater signal change in the vmPFC and vlPFC. Signal changes in the amygdala and vmPFC were not associated with disease expression. However, in the right vlPFC the Met158 allele was associated with greater activation in all family members with affective morbidity compared with relatives without a psychiatric diagnosis and healthy controls.

CONCLUSIONS

Our results suggest that the COMT Val158Met polymorphism has a pleiotropic effect within the neural networks subserving emotional processing. Furthermore the Met158 allele further reduces cortical efficiency in the vlPFC in individuals with affective morbidity.

P01-216-Frontopolar cortical inefficiency underpins both “hot” and “cold” cognitive dysfunction in bipolar disorder

Introduction

Emotional dysregulation in Bipolar Disorder (BD) is thought to be linked with prefrontal cortex (PFC) dysfunction associated with cognitive control coupled with increased or aberrant activation within regions associated with emotional processing.

Objectives

To determine the common and distinct patterns of functional brain abnormalities during affective and emotionally neutral cognitive processing in BD.

Aims

Current models of BD emphasise the relationship between mood dysregulation and fronto-limbic dysfunction during affective or “hot” processing. However, they do not account for deficits in emotionally neutral or “cold” tasks of memory and executive function which are also present in BD. Therefore the purpose of this study was to examine the neural correlates of affective decision making and working memory in BD.

Methods

Participants were 36 euthymic BD patients and 37 healthy controls matched for age, gender and IQ. FMRI was conducted during the Iowa Gambling Task (IGT) and the n-back working memory task as respective exemplars of “hot” and “cold” processing.

Results

There were no group differences in performance on either task. BD patients demonstrated a pattern of inefficient engagement within the ventral frontopolar PFC in both the IGT and n-back. These abnormalities showed task-related segregation along the medial-lateral dimension for “hot” and “cold” processing respectively. Patients also showed greater activation in the anterior cingulate cortex during the IGT and in the insula during the n-back. These regions are thought to respond to markers of autonomic arousal.

Conclusions

These data demonstrate ventral frontopolar PFC inefficiency as a shared abnormality underpinning both “hot” and “cold” processing deficits in BD.

Neural Activation During the STROOP Task in Bipolar Disorder Patients and Their Unaffected Relatives

Aims:

To examine potential similarities in neural activation during the STROOP colour word test (SCWT) in patients with Bipolar Disorder (BD) and their unaffected first degree relatives of BD patients as an expression of genetic predisposition.

Methods:

39 remitted BD patients were compared to 46 of their healthy relatives and to 42 controls. fMRI data were collected on a 1.5 T GE Signa MR system using a blocked periodic design and analysed in SPM5.

Results:

There was no statistically significant group difference in the behavioural performance. At the corrected cluster level threshold of p< 0.001 controls showed more activation than:

a.

Conclusion:

These findings suggest that changes in neural activation during response inhibition may reflect genetic predisposition to BD.