Bipolaroids: functional imaging in bipolar disorder

Sex effects on differentiating patients with major depressive disorder from bipolar disorder in depressive state: A fMRI study with follow-up

BACKGROUND

Bipolar disorder (BD) is difficult to discriminate from major depressive disorder (MDD) before the appearance of mania or hypomania. This study was designed to identify whether patients with MDD and those who converted to BD are distinguishable using dynamic amplitude low-frequency fluctuations (dALFF) and describe the sex effects on the identification of the two disorders.

METHODS

We compared the dALFF values of 35 BD patients who converted from MDD during the 2-year follow-up, 99 MDD patients, and 130 healthy controls (HCs) using two-way ANOVA. Pearson's correlation was used to compare dALFF in dysfunctional brain regions and clinical characteristics.

RESULTS

A main effect of diagnosis was discovered in the frontal and occipital gyrus. For the main effect of sex, both the left middle occipital gyrus and the medial part of the superior frontal gyrus had higher dALFF values in males compared to females. An interaction of sex and diagnosis effect was observed in the right precentral gyrus. Male MDD patients exhibited a higher dALFF value than male BD patients. Additionally, we discovered a higher dALFF value in females than in males in BD patients. WCST scores were positively associated with dALFF values in the frontal and occipital gyrus in MDD patients. Meanwhile, dALFF values in the occipital gyrus positively correlated with WCST in female MDD patients only.

LIMITATION

Most of the participants were on medication and the sample size was small.

CONCLUSIONS

Our study is the first to find the non-neglectable role of sex effects in differentiating BD and MDD at an early stage.

Facial emotion recognition and its correlation with executive functions in bipolar I patients and healthy controls

INTRODUCTION

The ability to recognize facial emotions is altered in patients with Bipolar Disorder (BD) during mood episodes and even in euthymia, while cognitive functioning is similarly impaired. This recognition is considered a fundamental skill for successful social interaction. However, it is unclear whether the ability to recognize facial emotions is correlated with the cognitive deficits observed in BD.

OBJECTIVE

The objective of this study was to evaluate Facial Emotion Recognition (FER) and its correlation with executive function (EF) in BD I patients during mania, depression and euthymia compared to healthy controls.

MATERIAL AND METHODS

A total of 110 patients with BD I, 18-40 years old were included (41 in manic episode; 31 in depressive episode and 38 euthymic). Patients were assessed for FER and EF (Wisconsin card sorting test - WCST), along with 96 healthy volunteers (18-40 years old) recruited from the University of São Paulo.

RESULTS

The results showed that BD I patients had lower FER performance compared to controls on fear subtests, happiness, the surprise test, and FER total scores. Moreover, BD I manic patients showed poorer performance for EF compared to controls. Six out of the seven variables of the WCST correlated with FER in both healthy controls and BD euthymic subjects but not in BD patients during mood episodes.

CONCLUSION

Cognitive deficits and difficulties recognizing facial emotions are present in all mood episodes in BD I patients, even during remission. Although FER is not considered a cognitive domain, these results suggest that, along with EF, it has a complementary function. Hence, further studies should investigate this issue in larger samples and verify whether these similarities also occur at a neurobiological level.

Trait and state dependent functional impairments in bipolar disorder

Bipolar disorder (BD) is characterized by abnormalities in emotion processing. Specifically, the processing of affective faces appears to be impaired. This study explored functional abnormalities in the neural network underlying the processing of facial affect in three different mood states (euthymic, depressed, and manic) associated with BD. Functional magnetic resonance imaging (fMRI) data were acquired from 18 healthy controls and 18 euthymic, 12 depressed, and 12 manic BD patients while viewing affective or neutral faces. Compared with controls, BD patients in all mood states showed reduced activation in the bilateral orbitofrontal cortex (OFC), indicating that activation in this region is independent of mood state. Activation in the amygdala, dorsolateral prefrontal cortex (DLPFC), and right temporal pole depended on mood state. Whereas activation levels of depressed patients were not significantly different from those of controls, activation levels in both euthymic and manic patients were significantly reduced compared with activation levels of both controls and depressed patients. However in the right DLPFC euthymic patients showed an increased level of activation compared with manic patients. These results add to the evidence for functional deficits in the affective network in BD patients, of which reduced bilateral OFC activation was found to be the most pronounced deficit across all mood states.

The role of BDNF as a mediator of neuroplasticity in bipolar disorder

The cognitive impairment and neuroanatomical changes that takes place among patients with bipolar disorder (BD) patients has been well described. Recent data suggest that changes in neuroplasticity, cell resilience and connectivity are the main neuropathological findings in BD. Data from differential lines of research converges to the brain-derived neurotrophic factor (BDNF) as an important contributor to the neuroplasticity changes described among BD patients. BDNF serum levels have been shown to be decreased in depressive and manic episodes, returning to normal levels in euthymia. BDNF has also been shown to decrease as the disorder progresses. Moreover, factors that negatively influence the course of BD, such as life stress and trauma have been shown to be associated with a decrease in BDNF serum levels. These findings suggest that BDNF plays a central role in the progression of BD. The present review discusses the role of BDNF as a mediator of the neuroplastic changes that occur in portion with mood episodes and the potential use of serum BDNF as a biomarker in BD.

Course and outcome after the first manic episode in patients with bipolar disorder: prospective 12-month data from the Systematic Treatment Optimization Program For Early Mania project

OBJECTIVE

To describe clinical characteristics, course, and outcome during a 1-year period after the first manic episode in patients with bipolar disorder (BD).

METHODS

This paper describes the project design, demographics, clinical outcomes, and predictors at 6 months to 1 year of follow-up of the first 53 recruited subjects with first-episode mania from the Systematic Treatment Optimization Program for Early Mania.

RESULTS

Survival analysis for recurrence of mood episodes showed that 46.7% of patients survived without a mood episode during 1-year of follow-up, and the mean time-to-mood event was 7.9 months. Earlier age of onset was the only variable that significantly predicted recurrence of mood episodes. When examined separately, the survival rates were 76% for a manic episode and 58.7% for a depressive episode.

CONCLUSION

These results suggest that recurrences are common after the first manic episode with more than one-half of the patients experiencing a mood event within 12 months. Aggressive treatment strategies aimed at preventing depressive episodes are needed in the management of early course BD.

Bipolar disorder as maladaptive arousal: a behavioral model and evidence

Bipolar disorder can be understood as a disorder of behavioral regulation. Manic and depressed individuals are impaired in the titration of appetitive arousal, possibly at the level of neuronal plasticity. An experiment in which fixed 5% CO2 stimulates respiration and blocks satiety tests the regulation of appetitive arousal. In preliminary analysis of data from 35 individuals (24 with bipolar disorder) individuals with bipolar disorder were more likely to fail to find a stable state of respiratory adjustment to CO2. If confirmed, the unstable respiratory response to CO2 may prove useful as a bipolar-disorder endophenotype.

Emotional memory in bipolar disorder

BACKGROUND

Cognitive impairment has been well documented in bipolar disorder. However, specific aspects of cognition such as emotional memory have not been examined.

AIMS

To investigate episodic emotional memory in bipolar disorder, as indicated by performance on an amygdala-related cognitive task.

METHOD

Twenty euthymic patients with bipolar disorder and 20 matched controls were recruited. Participants were shown a slide show of an emotionally neutral story, or a closely matched emotionally arousing story. One week later, participants were assessed on a memory-recall test.

RESULTS

In contrast with the pattern observed in controls, patients with bipolar disorder had no enhancement of memory for the emotional content of the story (F=14.7, d.f.=1,36, P<0.001). The subjective perception of the emotional impact of the emotional condition was significantly different from that of the neutral condition in controls but not in people with bipolar disorder.

CONCLUSIONS

Our data suggest that the physiological pattern of enhanced memory retrieval for emotionally bound information is blunted in bipolar disorder.

Making sense of neuroimaging in psychiatry

OBJECTIVE

Neuroimaging of psychiatric disorders has increased exponentially in the last decade; however, much of the uptake thus far has been in the realm of research. We anticipate that clinical use of neuroimaging modalities in psychiatry will increase dramatically in the near future and suggest that clinicians need to be aware of the potential applications.

METHOD

The authors conducted an extensive MEDLINE, EMBASE, PubMED and PsychInfo search of the published literature (1965-2007) using a variety of search terms to find relevant articles. Bibliographies of retrieved papers were further scrutinised for publications of interest, as were indices of books. Articles that reported clinically significant findings and research reports conducted using pertinent neuroimaging modalities were reviewed in detail.

RESULTS

The review suggests that exciting neuroimaging advances are being made that have relevance to psychiatry. Novel neuroimaging applications with potential clinical utility are rapidly emerging and the accessibility and use of these technologies will increase in coming years. Clinically meaningful findings have begun to emerge in mood disorders, post-traumatic stress disorder, schizophrenia and dementia. Coupling multimodal imaging with genetics and pharmacotherapeutic studies will further assist in understanding the pathophysiology of neuropsychiatric disorders.

CONCLUSION

It is important that clinicians understand the benefits and limitations of modern neuroimaging techniques and are also suitably equipped to appraise future developments. The use of neuroimaging in evaluating psychopathology is likely to impact upon the future nosology of psychiatric disorders, and assist in diagnosis and clinical management. The integrated use of neuroimaging in conjunction with clinical assessments promises to improve clinical care and markedly alter psychiatric practice.

Neuropsychological functioning in euthymic bipolar disorder: a meta-analysis

OBJECTIVE

Although cognitive deficits are prominent in symptomatic patients with bipolar disorder, the extent and pattern of cognitive impairment in euthymic patients remain uncertain.

METHOD

Neuropsychological studies comparing euthymic bipolar patients and healthy controls were evaluated. Across studies, effect sizes reflecting patient-control differences in task performance were computed for the 15 most frequently studied cognitive measures in the literature.

RESULTS

Across the broad cognitive domains of attention/processing speed, episodic memory, and executive functioning, medium-to-large performance effect size differences were consistently observed between patients and controls, favoring the latter. Deficits were not observed on measures of vocabulary and premorbid IQ.

CONCLUSION

Meta-analytic findings provide evidence of a trait-related neuropsychological deficit in bipolar disorder involving attention/processing speed, memory, and executive function. Findings are discussed with regard to potential moderators, etiologic considerations, limitations, and future directions in neuropsychological research on bipolar disorder.

Increased anterior cingulate cortex volume in bipolar I disorder

OBJECTIVE

Functional neuroimaging studies have implicated the anterior cingulate cortex (ACC) in the pathophysiology of bipolar disorder (BD), but findings from volumetric studies have been less consistent, therefore the purpose of the present study was to further investigate the existence of volumetric abnormalities in the ACC cortex of individuals with BD. In addition to methodological inconsistencies many previous studies have been lacking robustness clinically with respect to characterizing bipolar patients and comparison subjects. Hence, the present study matched the groups closely across a number of demographic parameters.

METHODS

Using magnetic resonance imaging, ACC volumes of 24 bipolar patients were compared to 24 gender-, age-, and education-matched control subjects, and these findings were further investigated in relation to both illness and treatment factors.

RESULTS

A significantly larger (26%) right ACC in bipolar patients than control subjects was seen, and this difference was not associated with a history of psychosis, familiality, or lithium treatment, after controlling for potential confounds. Patients reporting fewer affective episodes did, however, have significantly larger ACC volumes than controls, suggesting ACC volumetric changes early in the course of BD.

CONCLUSIONS

An increase in the size of the ACC may have important implications for the neurobiology of BD. It is suggested that attempts to control affective instability during the early stages of the illness necessitates greater ACC mediation via its role in conflict resolution and hence this is reflected in the increased size of the ACC early in the course of the illness.

Panic comorbidity with bipolar disorder: what is the manic-panic connection?

CONTEXT

Bipolar/panic comorbidity has been observed in clinical, community and familial samples. As both are episodic disorders of affect regulation, the common pathophysiological mechanism is likely to involve deficits in amygdala-mediated, plasticity-dependent emotional conditioning.

EVIDENCE

Neuronal genesis and synaptic remodeling occur in the amygdala; bipolar and panic disorders have both been associated with abnormality in the amygdala and related structures, as well as in molecules that modulate plasticity, such as serotonin, norepinephrine, brain-derived neurotrophic factor (BDNF) and corticotrophin releasing factor (CRF). These biological elements are involved in behavioral conditioning to threat and reward.

MODEL

Panic attacks resemble the normal acute fear response, but are abnormally dissociated from any relevant threat. Abnormal reward-seeking behavior is central to both manic and depressive syndromes. Appetites can be elevated or depressed; satisfaction of a drive may fail to condition future behavior. These dissociations may be the result of deficits in plasticity-dependent processes of conditioning within different amygdala subregions.

CONCLUSIONS

This speculative model may be a useful framework with which to connect molecular, cellular, anatomic and behavioral processes in panic and bipolar disorders. The primary clinical implication is that behavioral treatment may be critical to restore function in some bipolar patients who respond only partially to medications.

Executive functioning and theory of mind in euthymic bipolar disorder

OBJECTIVES

To examine the nature of executive deficits in euthymic patients with bipolar disorder (BD).

METHODS

Fifteen euthymic BD patients and 13 controls were administered a battery of executive tasks including verbal fluency, Stroop, Theory of Mind (ToM) tests and selected subtests from the Cambridge Neuropsychological Test Automated Battery (CANTAB). Self-report and clinician ratings of mood and social and occupational functioning were also obtained.

RESULTS

There were no significant differences between BD patients and controls on the primary measures of the following executive tasks: verbal fluency, attentional set-shifting, problem solving or planning. On secondary measures of speed, BD patients were slower to complete the first trial of the Stroop task (p = 0.001). Patients with BD committed more errors across all secondary measures. Patients performed poorly when compared with controls on tests of verbal ToM (p = 0.02), and although they performed non-verbal ToM tasks at a level comparable to controls (p = 0.60), they were slower to initiate a response (p = 0.006). ToM was not significantly correlated with any measure of social and occupational functioning; however it correlated with the achievement scores of the CANTAB Stockings of Cambridge task (Pearson's r = 0.68, p < 0.01).

CONCLUSIONS

Deficits found in euthymic bipolar patients suggest fronto-subcortical pathway dysfunction. This is consistent with other neuropsychological and neuroimaging research that points to a trait deficit in BD. Further investigation is necessary perhaps using more real-world tests.

Frontal lobe function in bipolar disorder: A multichannel near-infrared spectroscopy study

Frontal lobe dysfunction has been implicated as one of the pathophysiological bases of bipolar disorder. Detailed time courses of brain activation in the bipolar disorder group were investigated using multichannel near-infrared spectroscopy (NIRS), a recently developed functional neuroimaging technology with a high time resolution, and were compared with those in the major depression and healthy control groups. Seventeen patients with bipolar disorder, 11 equally depressed patients with major depression, and 17 healthy controls participated in the study. Changes in oxy hemoglobin concentration ([oxy-Hb]) during cognitive and motor tasks were monitored using frontal and temporal probes of two sets of 24-channel NIRS machines. [oxy-Hb] increases in the bipolar disorder group were smaller than those in the healthy control group during the early period of a verbal fluency task, larger than those in the major depression and healthy control groups during the late period of this task, and were smaller than those in the major depression group during a finger-tapping task. Depressive symptoms and antidepressant dosages did not correlate with [oxy-Hb] changes in the two patient groups. Bipolar disorder and major depression were characterized by preserved but delayed and reduced frontal lobe activations, respectively, in the present high-time-resolution study by multichannel NIRS.

A typical mood stabilizers: a "typical role for atypical antipsychotics

OBJECTIVE

To assess the potential role of atypical antipsychotics as mood stabilizers.

METHOD

A MedLine, PsychLIT, PubMed, and EMBASE literature search of papers published up to December 2004 was conducted using the names of atypical antipsychotics and a number of key terms relevant to bipolar disorder. Additional articles were retrieved by scrutinizing the bibliographies of review papers and literature known to the authors. Data pertinent to the objective was reviewed according to the various phases of bipolar disorder.

RESULTS

The data is most substantive for the use of atypical antipsychotics in mania, to the extent that an argument for a class effect of significant efficacy can be made. This does not extend to bipolar depression, however, good data is now emerging for some agents and will need to be considered for each individual agent as it accumulates. As regards mixed states and rapid cycling the evidence is thus far sparse and too few maintenance studies have been conducted to make any firm assertions. However, with respect to long-term therapy the atypical antipsychotics do have clinically significant side-effects of which clinicians need to be aware.

CONCLUSION

Based on the evidence thus far it is perhaps premature to describe the atypical antipsychotics as mood stabilizers. Individual agents may eventually be able to claim this label, however, much further research is needed especially with respect to maintenance and relapse prevention.

When euthymia is just not good enough: the neuropsychology of bipolar disorder

Bipolar disorder (BD) is a debilitating psychiatric illness that is uniquely characterized by switching between psychopathologically contrasting phases of mania and depression, often with intervening periods of euthymia. However, these periods of apparent clinical recovery (euthymia) are marked by subtle social, occupational, and cognitive impairments, profiled by recent neuropsychological investigations. Determining the cognitive changes across these three phases may help differentiate the disruptions that are mood state-dependent from those associated with underlying pathology. This article therefore critically reviews the reported neuropsychological impairments in BD and the methodological limitations facing such research. Integration of the available evidence, principally from the field of neuropsychology, when synthesized, implicates the prefrontal cortex in the etiopathogenesis of BD and posits cortical-subcortical-limbic disruption in recovered euthymic patients that manifests as cognitive dysfunction.

Structural and functional models of depression: from sub-types to substrates

OBJECTIVE

To present a functional model of depression facilitating research and clinical understanding.

METHOD

The authors conducted a systematic literature search and reviewed articles pertaining to the neurochemistry and pathophysiology of depressive disorders, focusing on the contribution made by the principal monoamines to three differing depressive structural sub-types (i.e. psychotic, melancholic and non-melancholic).

RESULTS

We suggest that the three structural depressive subtypes appear functionally underpinned by differential contributions of serotonergic, noradrenergic and dopaminergic neurotransmitters, so influencing phenotypic distinction (our structural model) and allowing an aetiological model to be derived with treatment specificity implications.

CONCLUSION

The functional model logically iterates with the structural model of depression and provides a useful framework for conceptualizing the depressive disorders. This model provides a logic for distinguishing between principal depressive subtypes, pursuing their functional underpinnings and explaining treatment differential effects across the three sub-types.

Bipolar disorder: it's all in your mind? The neuropsychological profile of a biological disorder

OBJECTIVE

To compare and contrast the neuropsychological profile of the 3 phases of bipolar disorder (BD) to achieve a better definition of BD and to identify potential state and trait deficits.

METHODS

We conducted a search for English-language papers published in journals from 1965 onward, using the following terms in Medline and Embase: neuropsychology or neuropsychological and BD, depression, mania, and euthymia. We scrutinized suitable subheadings and retrieved familiar papers and literature.

RESULTS

We initially identified more than 100 articles and then excluded reviews and papers that did not directly administer neuropsychological tests. This left 27 papers, which we further examined and the findings of which we tabulated and discussed. Cognitive and executive functioning deficits were found, including set-shifting, verbal fluency, planning, attention, and memory.

CONCLUSIONS

The neuropsychological deficits found in bipolar depression, mania or hypomania, and euthymia provide important insights into the pathophysiology of BD and may, in future studies, form the basis of clinically meaningful subtypes.