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

Neuroimaging and neuropathological findings in bipolar disorder

Bipolar disorder (BPD) is increasingly recognized as a neuropathological disorder characterized by reductions in grey matter (GM) volume, as measured by magnetic resonance imaging (MRI) and neuronal and postmortem glial cell changes. Here, we use an anatomical framework to discuss the neurobiology of BPD, focusing on individual components of the "visceromotor network" that regulates bodily homeostasis along with neurophysiological and neuroendocrine responses to stress. MRI-defined reductions in GM volume, combined with neuronal changes, are observed in the perigenual anterior cingulate cortex (ACC) of individuals with BPD, while postmortem glial cell loss is also a characteristic of Brodmann's Area 9. Both postmortem neuronal loss and reduced GM volume have been reported in the amygdala and hippocampus. These structural changes to components of the visceromotor network are associated with increased regional cerebral blood flow (rCBF) or blood oxygenated level-dependent (BOLD) activity in response to affective or rewarding stimuli, raising the possibility that the BPD-associated structural changes are secondary to a glutamate-driven excitotoxic process.

Abnormally increased effective connectivity between parahippocampal gyrus and ventromedial prefrontal regions during emotion labeling in bipolar disorder

Emotional liability and mood dysregulation characterize bipolar disorder (BD), yet no study has examined effective connectivity between parahippocampal gyrus and prefrontal cortical regions in ventromedial and dorsal/lateral neural systems subserving mood regulation in BD. Participants comprised 46 individuals (age range: 18-56 years): 21 with a DSM-IV diagnosis of BD, type I currently remitted; and 25 age- and gender-matched healthy controls (HC). Participants performed an event-related functional magnetic resonance imaging paradigm, viewing mild and intense happy and neutral faces. We employed dynamic causal modeling (DCM) to identify significant alterations in effective connectivity between BD and HC. Bayes model selection was used to determine the best model. The right parahippocampal gyrus (PHG) and right subgenual cingulate gyrus (sgCG) were included as representative regions of the ventromedial neural system. The right dorsolateral prefrontal cortex (DLPFC) region was included as representative of the dorsal/lateral neural system. Right PHG-sgCG effective connectivity was significantly greater in BD than HC, reflecting more rapid, forward PHG-sgCG signaling in BD than HC. There was no between-group difference in sgCG-DLPFC effective connectivity. In BD, abnormally increased right PHG-sgCG effective connectivity and reduced right PHG activity to emotional stimuli suggest a dysfunctional ventromedial neural system implicated in early stimulus appraisal, encoding and automatic regulation of emotion that may represent a pathophysiological functional neural mechanism for mood dysregulation in BD.

Prefrontal cortical and striatal activity to happy and fear faces in bipolar disorder is associated with comorbid substance abuse and eating disorder

BACKGROUND

The spectrum approach was used to examine contributions of comorbid symptom dimensions of substance abuse and eating disorder to abnormal prefrontal-cortical and subcortical-striatal activity to happy and fear faces previously demonstrated in bipolar disorder (BD).

METHOD

Fourteen remitted BD-type I and sixteen healthy individuals viewed neutral, mild and intense happy and fear faces in two event-related fMRI experiments. All individuals completed Substance-Use and Eating-Disorder Spectrum measures. Region-of-Interest analyses for bilateral prefrontal and subcortical-striatal regions were performed.

RESULTS

BD individuals scored significantly higher on these spectrum measures than healthy individuals (p<0.05), and were distinguished by activity in prefrontal and subcortical-striatal regions. BD relative to healthy individuals showed reduced dorsal prefrontal-cortical activity to all faces. Only BD individuals showed greater subcortical-striatal activity to happy and neutral faces. In BD individuals, negative correlations were shown between substance use severity and right PFC activity to intense happy faces (p<0.04), and between substance use severity and right caudate nucleus activity to neutral faces (p<0.03). Positive correlations were shown between eating disorder and right ventral putamen activity to intense happy (p<0.02) and neutral faces (p<0.03). Exploratory analyses revealed few significant relationships between illness variables and medication upon neural activity in BD individuals.

LIMITATIONS

Small sample size of predominantly medicated BD individuals.

CONCLUSION

This study is the first to report relationships between comorbid symptom dimensions of substance abuse and eating disorder and prefrontal-cortical and subcortical-striatal activity to facial expressions in BD. Our findings suggest that these comorbid features may contribute to observed patterns of functional abnormalities in neural systems underlying mood regulation in BD.

Abnormal amygdala-prefrontal effective connectivity to happy faces differentiates bipolar from major depression

BACKGROUND

Bipolar disorder is frequently misdiagnosed as major depressive disorder, delaying appropriate treatment and worsening outcome for many bipolar individuals. Emotion dysregulation is a core feature of bipolar disorder. Measures of dysfunction in neural systems supporting emotion regulation might therefore help discriminate bipolar from major depressive disorder.

METHODS

Thirty-one depressed individuals-15 bipolar depressed (BD) and 16 major depressed (MDD), DSM-IV diagnostic criteria, ages 18-55 years, matched for age, age of illness onset, illness duration, and depression severity-and 16 age- and gender-matched healthy control subjects performed two event-related paradigms: labeling the emotional intensity of happy and sad faces, respectively. We employed dynamic causal modeling to examine significant among-group alterations in effective connectivity (EC) between right- and left-sided neural regions supporting emotion regulation: amygdala and orbitomedial prefrontal cortex (OMPFC).

RESULTS

During classification of happy faces, we found profound and asymmetrical differences in EC between the OMPFC and amygdala. Left-sided differences involved top-down connections and discriminated between depressed and control subjects. Furthermore, greater medication load was associated with an amelioration of this abnormal top-down EC. Conversely, on the right side the abnormality was in bottom-up EC that was specific to bipolar disorder. These effects replicated when we considered only female subjects.

CONCLUSIONS

Abnormal, left-sided, top-down OMPFC-amygdala and right-sided, bottom-up, amygdala-OMPFC EC during happy labeling distinguish BD and MDD, suggesting different pathophysiological mechanisms associated with the two types of depression.

Bipolar disorder: emotional dysregulation and neuronal vulnerability

Bipolar disorder is clinically characterized by fluctuating affect, and neuropsychologically by impairment in executive functions. Such phenomena are consistent with the centrality of emotional dysregulation and impulsivity to bipolar disorder. They are also consistent with a key role for prefrontal-subcortical (striatal-thalamic) and associated limbic circuitry in its mediation. Furthermore, there is growing data on the cellular mechanisms contributing to neuronal vulnerability in this mediating circuitry.

Elevated left and reduced right orbitomedial prefrontal fractional anisotropy in adults with bipolar disorder revealed by tract-based spatial statistics

CONTEXT

Diffusion tensor imaging (DTI) studies in adults with bipolar disorder (BD) indicate altered white matter (WM) in the orbitomedial prefrontal cortex (OMPFC), potentially underlying abnormal prefrontal corticolimbic connectivity and mood dysregulation in BD.

OBJECTIVE

To use tract-based spatial statistics (TBSS) to examine WM skeleton (ie, the most compact whole-brain WM) in subjects with BD vs healthy control subjects.

DESIGN

Cross-sectional, case-control, whole-brain DTI using TBSS.

SETTING

University research institute.

PARTICIPANTS

Fifty-six individuals, 31 having a DSM-IV diagnosis of BD type I (mean age, 35.9 years [age range, 24-52 years]) and 25 controls (mean age, 29.5 years [age range, 19-52 years]).

MAIN OUTCOME MEASURES

Fractional anisotropy (FA) longitudinal and radial diffusivities in subjects with BD vs controls (covarying for age) and their relationships with clinical and demographic variables.

RESULTS

Subjects with BD vs controls had significantly greater FA (t > 3.0, P 3.0, P

CONCLUSIONS

To our knowledge, this is the first study to use TBSS to examine WM in subjects with BD. Subjects with BD vs controls showed greater WM FA in the left OMPFC that diminished with age and with alcohol or other drug abuse, as well as reduced WM FA in the right OMPFC. Mood stabilizers and depressed episode reduced WM FA in left-sided sensory visual processing regions among subjects with BD. Abnormal right vs left asymmetry in FA in OMPFC WM among subjects with BD, likely reflecting increased proportions of left-sided longitudinally aligned and right-sided obliquely aligned myelinated fibers, may represent a biologic mechanism for mood dysregulation in BD.

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MESH Headings

• Adult
• Anisotropy
• Antipsychotic Agents
• Bipolar Disorder/diagnosis
• Bipolar Disorder/drug therapy
• Bipolar Disorder/physiopathology
• Case-Control Studies
• Cross-Sectional Studies
• Demography
• Diffusion Magnetic Resonance Imaging
• Female
• Functional Laterality/drug effects
• Functional Laterality/physiology
• Humans
• Limbic System/physiopathology
• Male
• Middle Aged
• Nerve Net/physiopathology
• Orbit
• Prefrontal Cortex/anatomy & histology
• Prefrontal Cortex/drug effects
• Prefrontal Cortex/physiopathology

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Grants

• R01 MH076971 NIMH NIH HHS
• UL1 TR000005 NCATS NIH HHS
• 1 R01 MH076971-01 NIMH NIH HHS

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Affiliation(s)

Amelia Versace Department of Psychiatry, University of Pittsburgh School of Medicine, 121 Meyran Ave, Pittsburgh, PA 15213, USA.
Jorge R C Almeida
Stefanie Hassel
Nicholas D Walsh
Massimiliano Novelli
Crystal R Klein
David J Kupfer
Mary L Phillips

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Collaborators Collapse

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.

Neural activation during encoding of emotional faces in pediatric bipolar disorder

OBJECTIVE

Neurobiological understanding of bipolar disorder (BD) is limited by a paucity of functional magnetic resonance imaging (fMRI) research examining correlates of psychological processes. To begin to address these limitations, the current study tests the hypothesis that pediatric BD (PBD) subjects exhibit altered neural activation during encoding of emotional faces compared to typically developing controls.

METHODS

Pediatric BD subjects (n=23; mean age=14.2+/-3.1 years) and controls (n=22; mean age=14.7+/-2.3 years) were matched on age, gender, and IQ. In this event-related fMRI study, subjects were scanned while viewing emotional faces and given a surprise recognition memory test 30 min postscan. Our main outcome measure was between-group differences in neural activation during successful versus unsuccessful face encoding.

RESULTS

Pediatric BD youth exhibited reduced memory for emotional faces, relative to healthy comparisons, particularly on fearful faces. Event-related fMRI analyses controlling for this behavioral difference showed that PBD subjects, compared to controls, had increased neural activation in the striatum and anterior cingulate cortex when successfully encoding happy faces and in the orbitofrontal cortex when successfully encoding angry faces. There were no between-group differences in neural activation during fearful face encoding.

CONCLUSIONS

Our results extend what is known about memory and face emotion processing impairments in PBD subjects by showing increased fronto-striatal activation during encoding of emotional faces. Further work is required to determine the impact of mood state, medication, and comorbid illnesses on these findings.