Stroop performance in bipolar disorder: further evidence for abnormalities in the ventral prefrontal cortex

Lower orbital frontal white matter integrity in adolescents with bipolar I disorder

OBJECTIVE

To examine white matter microstructure, as assessed via diffusion tensor imaging (DTI), in adolescents with bipolar I disorder compared with control volunteers.

METHOD

Twenty-six (12 male and 14 female subjects) adolescents (mean age, 16.0 years) with bipolar I disorder and 26 (14 male and 12 female subjects) control volunteers (mean age, 15.3 years) completed structural and DTI examinations. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) maps were compared between groups in the brain white matter using a voxelwise analysis after intersubject registration to Talairach space. Exploratory analyses were performed to assess structure-function correlations in a subgroup of 11 patients with available neuropsychological measures.

RESULTS

Compared with the control volunteers, the patients demonstrated abnormalities in white matter regions predicted to differ a priori between groups, including lower FA in the right orbital frontal lobe and higher ADC in the right and left subgenual region (p <.005, uncorrected; cluster size >or= 100). There were no areas of higher FA or lower ADC in patients compared with control volunteers. Lower FA across regions that differed significantly between groups correlated significantly with slower visuomotor speed among patients with bipolar disorder.

CONCLUSIONS

Abnormalities involving the orbital frontal and subgenual white matter in adolescents with bipolar disorder are consistent with neurobiological models that implicate dysregulation of affective systems and impulsivity in the pathophysiology of the disorder. Preliminary findings suggest that white matter abnormalities in pediatric bipolar disorder have functional correlates and may be useful in constructing neurobiological models of the disorder.

The phenomenology of bipolar disorder: what drives the high rate of medical burden and determines long-term prognosis?

Bipolar disorder (BD) has been classically described as one of episodic mood disturbances. New evidence suggests that a chronic course and multisystem involvement is the rule, rather than the exception, and that together with disturbances of circadian rhythms, mood instability, cognitive impairment, a high rate of medical burden is often observed. The current diagnostic approach for BD neither describes the multisystem involvement that the recent literature has highlighted nor points toward potential predictors of long- term outcome. In light of the new evidence that the long-term course of BD is associated with a high prevalence of psychiatric comorbidity and an increased mortality from medical disease, we propose a multidimensional approach that includes several symptom domains, namely affective instability, circadian rhythm dysregulation, and cognitive and executive dysfunction, presenting in various combinations that give shape to each individual presentation, and offers potential indicators of overall long-term prognosis.

Executive and verbal working memory dysfunction in first-degree relatives of patients with bipolar disorder

The authors aimed to investigate cognitive performance of first-degree relatives of probands with bipolar disorder (BD). They hypothesized that the relatives of BD patients would have impaired performance on cognitive tests of frontal-executive functions. A neuropsychological battery was administered to 34 first-degree relatives of BD probands and 25 control subjects. Relatives showed significant impairment in verbal working memory and executive function. Verbal memory and psychomotor performances of relatives were not different from control subjects. One particular component of executive function, cognitive flexibility, was associated with family history of mood episodes with psychotic features. Verbal working memory and executive function deficits may be useful endophenotypic markers of genetic vulnerability to BD.

Elevated striatal and decreased dorsolateral prefrontal cortical activity in response to emotional stimuli in euthymic bipolar disorder: no associations with psychotropic medication load

OBJECTIVE

To examine abnormal patterns of frontal cortical-subcortical activity in response to emotional stimuli in euthymic individuals with bipolar disorder type I in order to identify trait-like, pathophysiologic mechanisms of the disorder. We examined potential confounding effects of total psychotropic medication load and illness variables upon neural abnormalities.

METHOD

We analyzed neural activity in 19 euthymic bipolar and 24 healthy individuals to mild and intense happy, fearful and neutral faces.

RESULTS

Relative to healthy individuals, bipolar subjects had significantly increased left striatal activity in response to mild happy faces (p < 0.05, corrected), decreased right dorsolateral prefrontal cortical (DLPFC) activity in response to neutral, mild and intense happy faces, and decreased left DLPFC activity in response to neutral, mild and intense fearful faces (p < 0.05, corrected). Bipolar and healthy individuals did not differ in amygdala activity in response to either emotion. In bipolar individuals, there was no significant association between medication load and abnormal activity in these regions, but a negative relationship between age of illness onset and amygdala activity in response to mild fearful faces (p = 0.007). Relative to those without comorbidities, bipolar individuals with comorbidities showed a trend increase in left striatal activity in response to mild happy faces.

CONCLUSIONS

Abnormally increased striatal activity in response to potentially rewarding stimuli and decreased DLPFC activity in response to other emotionally salient stimuli may underlie mood instabilities in euthymic bipolar individuals, and are more apparent in those with comorbid diagnoses. No relationship between medication load and abnormal neural activity in bipolar individuals suggests that our findings may reflect pathophysiologic mechanisms of the illness rather than medication confounds. Future studies should examine whether this pattern of abnormal neural activity could distinguish bipolar from unipolar depression.

Meta-analysis of magnetic resonance imaging studies of the corpus callosum in bipolar disorder

OBJECTIVE

The corpus callosum (CC) plays a pivotal role in inter-hemispheric transfer and integration of information and is a relatively understudied structure in bipolar disorder (BD). Magnetic resonance imaging (MRI) studies have reported callosal abnormalities in this condition but findings have been inconsistent. Structural changes affecting the CC may underlie functional abnormalities in BD and could contribute to, or explain the pathophysiology of, the condition.

METHOD

A systematic review was carried out to identify, appraise and summarize MRI studies which compared callosal areas in BD with an unrelated control group. The findings were then synthesized using random effects meta-analysis. Consideration was given to a number of variables to explain heterogeneity.

RESULTS

Five case-control studies were identified. Bipolar patients showed reduced callosal areas in comparison with healthy volunteers with no evidence of heterogeneity or publication bias.

CONCLUSION

Findings from this study indicate that callosal areas are reduced in BD and suggest that a failure to integrate information across the hemispheres may contribute to the pathophysiology of the disorder. Further research is necessary to clarify the underlying cellular changes leading to these morphometric differences.

Cognitive neuroscience and brain imaging in bipolar disorder

Bipolar disorder is characterized by a combination of state-related changes in psychological functíon that are restricted to illness episodes, coupled with trait-related changes that persist through periods of remission, irrespective of symptom status. This article reviews studies that have investigated the brain systems involved in these state-and trait-related changes, using two techniques: (i) indirect measures of neurocognitive function, and (ii) direct neuroimaging measures of brain function during performance of a cognitive task. Studies of neurocognitive function in bipolar disorder indicate deficits in three core domains: attention, executive function, and emotional processing. Functional imaging studies implicate pathophysiology in distributed neural circuitry that includes the prefrontal and anterior cingulate cortices, as well as subcortical limbic structures including the amygdala and the ventral striatum. Whilst there have been clear advances in our understanding of brain changes in bipolar disorder, there are limited data in bipolar depression, and there is limited understanding of the influence of clinical variables including medication status, illness severity, and specific symptom dimensions.

A neural model of voluntary and automatic emotion regulation: implications for understanding the pathophysiology and neurodevelopment of bipolar disorder

The ability to regulate emotions is an important part of adaptive functioning in society. Advances in cognitive and affective neuroscience and biological psychiatry have facilitated examination of neural systems that may be important for emotion regulation. In this critical review we first develop a neural model of emotion regulation that includes neural systems implicated in different voluntary and automatic emotion regulatory subprocesses. We then use this model as a theoretical framework to examine functional neural abnormalities in these neural systems that may predispose to the development of a major psychiatric disorder characterized by severe emotion dysregulation, bipolar disorder.

Paliperidone as a mood stabilizer: a pre-frontal cortex synaptoneurosomal proteomics comparison with lithium and valproic acid after chronic treatment reveals similarities in protein expression

A series of recent studies has demonstrated that the molecules involved in regulation of neuronal plasticity are also involved in the mode of action of antidepressants and mood stabilizer drugs. Intracellular calcium signaling, energy metabolism, and neuronal plasticity can be influenced by inducing axonal remodeling and increasing levels of certain synaptic proteins. Because antipsychotic drugs are used as mood stabilizers our studies focused on a newly-marketed antipsychotic drug, paliperidone. We determined changes in rat synaptoneurosomal proteins after chronic treatment with paliperidone, lithium salt, or valproic acid in order to find similarities or differences between the mode of action of paliperidone and these two classical mood stabilizers. We determined differential protein expression profiles in prefrontal cortex (PFC) of male Sprague-Dawley rats (n = 4/group). Synaptoneurosomal-enriched preparations were obtained from PFC after chronic treatment with these three drugs. Proteins were separated by 2D-DIGE and identified by nano-LC-MS/MS. We observed similar protein expression profiles at the synaptoneurosomal level, suggesting that the mode of action for paliperidone is similar to that of lithium and valproic acid. However, the expression profile for paliperidone was more similar to that of lithium. Pathways affected in common by these two drugs included oxidative phosphorylation, electron transport, carbohydrate metabolism, and post-synaptic cytokinesis implicating the effects of these drugs in signaling pathways, energy metabolism, and synaptic plasticity.

Functional brain abnormalities in psychiatric disorders: neural mechanisms to detect and resolve cognitive conflict and interference

In the present article, we review functional neuroimaging studies on interference processing and performance monitoring in three groups of psychiatric disorders, (1) mood disorders, (2) schizophrenia, and (3) obsessive-compulsive disorder (OCD). Ad (1) Behavioral performance measures suggest an impaired interference resolution capability in symptomatic bipolar disorder patients. A series of neuroimaging analyses found alterations in the ACC-DLPFC system in mood disorder (unipolar depressed and bipolar) patients, putatively reflective of an abnormal interplay of monitoring and executive neurocognitive functions. Other studies of euthymic bipolar patients showed relatively decreased interference-related activation in rostroventral PFC which conceivably underlies defective inhibitory control. Ad (2) Behavioral Stroop studies revealed a specific performance pattern of schizophrenia patients (normal RT interference but increased error interference and RT facilitation) suggestive of a deficit in ignoring irrelevant (word) information. Moreover, reduced/absent behavioral post-error and post-conflict adaptation effects suggest alterations in performance monitoring and/or adjustment capability in these patients. Neuroimaging findings converge to suggest a disorder-related abnormal neurophysiology in ACC which consistently showed conflict- and error-related hypoactivation that, however, appeared to be modulated by different factors. Moreover, studies suggest a specific deficit in context processing in schizophrenia, evidently related to activation reduction in DLPFC. Ad (3) Behavioral findings provide evidence for impaired interference resolution in OCD. Neuroimaging results consistently showed conflict- and error-related ACC hyperactivation which--conforming OCD pathogenesis models--can be conclusively interpreted as reflecting overactive performance monitoring. Taken together, interference resolution and performance monitoring appeared to be fruitful concepts in the investigation of neurocognitive deficits in psychiatric disorders.

Neural basis of abnormal response to negative feedback in unmedicated mood disorders

Depressed individuals show hypersensitivity to negative feedback during cognitive testing, which can precipitate subsequent errors and thereby impair a broad range of cognitive abilities. We studied the neural mechanisms underlying this feedback hypersensitivity using functional magnetic resonance imaging (fMRI) with a reversal learning task that required subjects to ignore misleading negative feedback on some trials. Thirteen depressed subjects with major depressive disorder (MDD), 12 depressed subjects with bipolar disorder (BD) and 15 healthy controls participated. The MDD group, but not the BD group, demonstrated enhanced sensitivity to negative feedback compared to controls, as indicated by the rates of rule reversal following misleading negative feedback. In the control and BD groups, hemodynamic activity was significantly higher in the dorsomedial and ventrolateral prefrontal cortices during reversal shifting, and significantly lower in the right amygdala in response to negative feedback. The extent to which the amygdala showed less activity during negative feedback correlated inversely with the behavioral tendency to reverse after misleading feedback. This effect was not present in the MDD group, who also failed to recruit the prefrontal cortex during behavioral reversal. Hypersensitivity to negative feedback is present in unmedicated depressed patients with MDD. Disrupted top-down control by the prefrontal cortex of the amygdala may underlie this abnormal response to negative feedback in unipolar depression.

Theory of mind and social inference in children and adolescents with bipolar disorder

BACKGROUND

Deficits in theory of mind (ToM), or the ability to infer what another person is thinking or feeling, have been reported in manic and euthymic adults with bipolar disorder. To date, there have been no investigations of ToM in pediatric bipolar disorder (PBD). The aim of the current study was to investigate this ability in PBD patients and healthy controls.

METHOD

PBD patients (n=26) and intellectually and demographically similar healthy comparison subjects (n=20) were administered two ToM tasks. In the Affective Story Task, subjects were read positive-, negative- and neutral-valenced stories, and were assessed on their ability to recognize that a misleading series of events could lead one character to develop a false belief about another character. On the Hinting Task, subjects were required to infer the real intentions behind subtle hints.

RESULTS

The PBD group performed significantly more poorly than controls on the Hinting Task and the positive and negative conditions of the Affective Story Task. In the PBD group only, younger age, earlier illness onset and manic symptoms were associated with poorer ToM performance.

CONCLUSIONS

Consistent with past findings in adult bipolar disorder (BD), PBD youth performed more poorly than controls on ToM tasks. Data suggest that ToM ability may be more impaired in affectively charged contexts. Additionally, an earlier onset of illness among PBD youth may interfere with the development of social-cognitive skills. ToM disturbances may be a useful treatment target in PBD, with the aim of facilitating more accurate assessment of social cues and better interpersonal functioning.

Medication effects in neuroimaging studies of bipolar disorder

OBJECTIVE

Neuroimaging studies are promising components for a new diagnostic framework for bipolar disorder, but a major issue is the potential confound of psychotropic medication upon experimental measures. Withdrawing all individuals from medication and examining only unmedicated individuals may be clinically unfeasible, and examining only unmedicated individuals may render findings less generalizable.

METHOD

The authors review structural and functional neuroimaging studies of medicated and unmedicated patients with bipolar disorder to discern the possible confounding effect of medication.

RESULTS

Findings from studies identified on MEDLINE that included medicated individuals with bipolar disorder indicated either no significant effect or ameliorative effects of psychotropic medications on abnormal structural and functional neuroimaging measures relevant to pathophysiologic mechanisms of the disorder. Different strategies for assessing medication effects are compared.

CONCLUSIONS

Neuroimaging studies of bipolar disorder ideally should recruit both unmedicated and medicated individuals. Individuals who are unable to tolerate medication withdrawal likely have more severe illness and are especially informative for research examining biomarkers of illness and treatment response.

Structural brain correlates of response inhibition in Bipolar Disorder I

Deficits in response inhibition are a prominent feature of Bipolar Disorder, type I (BDI). The purpose of this study was to examine the relationship between inhibitory control and cerebral structure as it may inform our understanding of the pathophysiology of BDI. Inhibitory control was measured in remitted patients with BDI (n = 44) and healthy controls (n = 44), using the interference score from the Stroop Colour Word Task and the scaled total error score from the Hayling Sentence Completion Test. Structural magnetic resonance imaging brain scans were also obtained for all participants. For both measures, better performance in controls correlated positively with gray matter volume in the dorsal and ventral prefrontal cortical (PFC) regions with parietal involvement additionally seen for the interference score. In contrast, better inhibitory control in BDI patients correlated positively with gray matter volume in the right parietal cortical regions, namely the cuneus for the scaled total error score and the inferior parietal lobule for the interference score. The observed lack of correlation between PFC grey matter and measures of inhibitory control in BDI patients is suggestive of PFC dysfunction; the correlation between response inhibition and parietal grey matter volume may be indicative of a compensatory involvement of the parietal cortices in BDI.

Divergent plasticity of prefrontal cortex networks

The 'executive' regions of the prefrontal cortex (PFC) such as the dorsolateral PFC (dlPFC) and its rodent equivalent medial PFC (mPFC) are thought to respond in concert with the 'limbic' regions of the PFC such as the orbitofrontal (OFC) cortex to orchestrate behavior that is consistent with context and expected outcome. Both groups of regions have been implicated in behavioral abnormalities associated with addiction and psychiatric disorders, in particular, schizophrenia and mood disorders. Theories about the pathophysiology of these disorders, however, incorporate abnormalities in discrete PFC regions independently of each other or assume they are one and the same and, thus, bunch them under umbrella of 'PFC dysfunction.' Emerging data from animal studies suggest that mPFC and OFC neurons display opposing patterns of plasticity during associative learning and in response to repeated exposure to psychostimulants. These data corroborate clinical studies reporting different patterns of activation in OFC versus dlPFC in individuals with schizophrenia or addictive disorders. These suggest that concomitant but divergent engagement of discrete PFC regions is critical for learning stimulus-outcome associations, and the execution of goal-directed behavior that is based on these associations. An atypical interplay between these regions may lead to abnormally high or low salience assigned to stimuli, resulting in symptoms that are fundamental to many psychiatric and addictive disorders, including attentional deficits, improper affective response to stimuli, and inflexible or impulsive behavior.

Evidence of disrupted prepulse inhibition in unaffected siblings of bipolar disorder patients

BACKGROUND

Prepulse inhibition (PPI) of the startle response refers to a reduction in the response to a strong stimulus (pulse) if preceded shortly by a weak stimulus (prepulse). Disrupted PPI is thought to reflect abnormalities in the inhibitory control of information processing. Reduced PPI has been reported in mania, although it is not clear whether it represents a trait feature of bipolar disorder (BD). To address this issue, the present study examined whether disrupted PPI is present in individuals at high risk for BD.

METHODS

Twenty-one remitted BD patients and 19 of their unaffected siblings were compared with 17 age- and gender-matched healthy volunteers on tests of acoustic startle reactivity and PPI of the startle response.

RESULTS

There were no group differences in startle reactivity. Compared with healthy individuals, BD patients and their unaffected siblings showed lower PPI. In the patient group, no significant correlations were found between PPI and measures of symptom and disease severity or medication.

CONCLUSIONS

This is the first study to report reduced PPI in remitted BD patients and their unaffected first-degree relatives. This finding, although in need of replication, suggests that PPI disruption may represent a trait deficit in BD associated with genetic predisposition.

Neuroimaging in bipolar disorder: a critical review of current findings

Bipolar I disorder (BPI) is among the top 10 most debilitating illnesses globally. In this critical review, we first review recent functional neuroimaging findings in two core domains of pathology in BPI: emotion processing and executive control. These abnormalities in core domains represent potential endophenotypes of the illness. We then show that an emerging number of studies have demonstrated that neuroimaging can help to identify endophenotypic markers whose identification would help to clarify diagnosis and discriminate the depression in BPI from that of unipolar depression and identify at-risk individuals who will subsequently develop the illness (to facilitate early intervention). We end by reviewing the new directions in neuroimaging in BPI, including studies of children with bipolar disorder, potential medication effects, and the use of newer neuroimaging techniques to help us achieve the previously mentioned goals of improving BPI patients' mental well-being.

A functional MRI study of a paced motor activation task to evaluate frontal-subcortical circuit function in bipolar depression

The primary aim of this functional magnetic resonance imaging (fMRI) study was to test the utility of a paced motor activation task to evaluate frontal-subcortical (FSC) circuit function in bipolar depression. A secondary aim was to determine if utilizing both a motor and cognitive activation paradigm (Stroop) would provide information about the potential role of FSC dysfunction in the cognitive symptoms of bipolar depression. Analysis of the control group (n=15) alone revealed that the motor task activated FSC structures. Comparison of the control to bipolar group (n=14) revealed significant differences between the groups in striatum as well as cortical areas with FSC connections in response to the non-dominant-hand motor task. In response to the Stroop, there were significant differences between the groups in portions of the bilateral posterior cingulate and occipital cortex, but not in FSC structures. While these results must be considered preliminary, this work supports further studies of paced motor tasks to probe FSC function. Further, it suggests that the use of both a cognitive and motor task in the same study provides useful information about brain function. Finally, it supports the literature implicating FSC circuit abnormalities in bipolar disorder.

Identifying functional neuroimaging biomarkers of bipolar disorder: toward DSM-V

Bipolar disorder is one of the most debilitating and common illnesses worldwide. Individuals with bipolar disorder frequently present to clinical services when depressed but are often misdiagnosed with unipolar depression, leading to inadequate treatment and poor outcome. Increased accuracy in diagnosing bipolar disorder, especially during depression, is therefore a key long-term goal to improve the mental health of individuals with the disorder. The attainment of this goal can be facilitated by identifying biomarkers reflecting pathophysiologic processes in bipolar disorder, namely impaired emotion regulation, impaired attention, and distractibility, which persist during depression and remission and are not common to unipolar depression. In this critical review, we examine the feasibility of identifying biomarker of bipolar disorder by discussing existing findings regarding functional abnormalities in neural systems underlying emotion processing (amygdala centered), working memory, and attention (dorsolateral prefrontal cortex centered) that persist through bipolar depression and remission and are bipolar specific rather than common to unipolar depression. We then focus on future research goals relating to major clinical problems in bipolar disorder, including, the identification of biomarkers allowing detection of individuals at risk of subsequent development of the disorder. Bipolar disorder is a common, debilitating, and potentially fatal disorder. Current and future research in bipolar disorder should focus on identification of disorder biomarkers to improve diagnostic accuracy and the mental heath of those with the disorder.

Bipolar disorder: how far are we from a rigorous definition and effective management?

Bipolar disorder is a pathological disturbance of mood, characterized by waxing and waning manic, depressive and, sometimes distinctly mixed states. A diagnosis of bipolar disorder can only be made with certainty when the manic syndrome declares itself. Most individuals who are diagnosed with this disorder will experience both poles of the illness recurrently, but depressive episodes are the commonest cause of morbidity and, indeed, of death by suicide. Twin, adoption and epidemiological studies suggest a strongly genetic aetiology. It is a genetically and phenotypically complex disorder. Thus, the genes contributing are likely to be numerous and of small effect. Individuals with bipolar disorder also display deficits on a range of neuropsychological tasks in both the acute and euthymic phases of illness and correlations between number of affective episodes experienced and task performance are commonly reported. Current self-report and observer-rated scales are optimized for unipolar depression and hence limited in their ability to accurately assess bipolar depression. The development of a specific depression rating scale will improve the assessment of bipolar depression in both research and clinical settings. It will improve the development of better treatments and interventions. Guidelines support the use of antidepressants for bipolar depression. With regard to the adverse effects of antidepressants for bipolar depression, double-blind, placebo-controlled data suggest that antidepressant monotherapy or the addition of a tricyclic antidepressant may worsen the course of bipolar disorder. Importantly, adjunctive psychotherapies add significantly (both statistically and clinically) to the efficacy of pharmacological treatment regimens. The successful management of bipolar disorder clearly demands improved recognition of bipolar disorder and effective long-term treatment for bipolar depression as well as mania.

Distinct mechanisms of altered brain activation in patients with multiple sclerosis

Cerebral reorganization may limit the effects of central nervous system tissue damage on cognition in patients with multiple sclerosis (MS). This study investigated fMRI activation patterns in patients with relapsing-remitting MS and healthy control subjects during performance of a delayed recognition task. As intended, fMRI task performance was similar in the MS and the control group, whereas neuropsychological testing revealed reduced performance in the patient group on the Paced Serial Addition Test, a reference task for the assessment of cognitive function in MS. Patients overall showed more activation in left posterior parietal cortex than healthy control subjects. Global gray matter atrophy in the patient group was associated with low PASAT scores. In a multiple regression analysis including white matter lesion load and gray matter atrophy as covariates, PASAT performance correlated with activation in left posterior parietal cortex and right anterior midfrontal gyrus, indicating a reallocation of neuronal resources to help preserve function. Global gray matter atrophy correlated with activation in bilateral prefrontal cortex, dorsal ACC and left posterior parietal cortex and, furthermore, was associated with a low degree of deactivation in rostral ACC, suggesting neural inefficiency and consistent with a reduced capacity to modulate between frontoparietal task-associated activation and 'default network' activity. The current study provides evidence that altered brain activation in MS patients has two distinct components, one related to compensatory processes and one to neural inefficiency associated with tissue damage.

Will neuroimaging ever be used to diagnose pediatric bipolar disorder?

There is a great need for discovery of biological markers that could be used diagnostically for pediatric onset disorders, particularly those with potentially confusing phenomenology such as pediatric-onset bipolar disorder (BD). Obtaining these markers would help overcome current subjective diagnostic techniques of relying on parent and child interview and symptomatic history. Brain imaging may be the most logical choice for a diagnostic tool, and certain neurobiological abnormalities have already been found in pediatric BD. However, much work remains to be done before neuroimaging can be used reliably to diagnose this disorder, and because of the nature of BD and the limitations of imaging technology and technique, neuroimaging will likely at most be only a diagnostic aide in the near future. In this paper we discuss the characteristics of pediatric BD that complicate the use of biological markers as diagnostic tools, how neuroimaging techniques have been used to study pediatric BD so far, and the limitations and potential of such techniques for future diagnostic use.

The role of functional neuroimaging in exploring the overlap between borderline personality disorder and bipolar disorder

In light of the recent discussions of possible diagnostic overlap between borderline personality disorder and bipolar disorder, we explored the neuroimaging literature to determine if findings from this literature might illuminate the issue of overlap between the two diagnoses. We looked at studies of executive functions and emotion-related functions. Although similar brain areas have been explored in each population and several findings are suggestive of overlap, as well as differences between the two disorders, conclusions are limited because of the lack of studies that employed the exact same paradigm in the two patient groups. The authors suggest methods for conducting future neuroimaging research that may better clarify some of these issues of possible diagnostic overlap.