Emotion regulation deficits in euthymic bipolar I versus bipolar II disorder: a functional and diffusion‐tensor imaging study

Abstract

ObjectivesEmotion regulation deficits are a core feature of bipolar disorder. However, their potential neurobiological underpinnings and existence beyond bipolar I disorder remain unexplored. Our main goal was to investigate whether both individuals with bipolar I and bipolar II disorder show deficits in emotion regulation during an attention control task, and to explore the neurophysiological underpinnings of this potential deficit.MethodsTwenty healthy controls, 16 euthymic participants with bipolar I disorder, and 19 euthymic participants with bipolar II disorder completed psychometric and clinical assessments, a neuroimaging emotion regulation paradigm, and an anatomical diffusion-weighted scan. Groups were matched for age, gender, and verbal IQ.ResultsDuring the presence of emotional distracters, subjects with bipolar I disorder showed slowed reaction times to targets, and increased blood oxygenation level-dependent (BOLD) responses in the amygdala, accumbens, and dorsolateral prefrontal cortex, but not increased inverse functional connectivity between these prefrontal and subcortical areas, and altered white matter microstructure organization in the right uncinate fasciculus. Subjects with bipolar II disorder showed no altered reaction times, increased BOLD responses in the same brain areas, increased inverse functional connectivity between the prefrontal cortex and amygdala, and no abnormalities in white matter organization.ConclusionsParticipants with bipolar I disorder showed abnormalities in functional and anatomical connectivity between prefrontal cortices and subcortical structures in emotion regulation circuitry. However, these deficits did not extend to subjects with bipolar II disorder, suggesting fundamental differences in the pathophysiology of bipolar disorder subtypes.

Cognitive variability in bipolar II disorder: who is cognitively impaired and who is preserved

“…All these data suggest that BD‐II is not a milder form of BD . Furthermore, some differences have been reported in neural anatomy and function , supporting the hypothesis of neurobiological differences between the two subtypes. Other differences in psychological factors such as cognitive and coping styles and their relationships with symptoms across BD subtypes have been also described .…”

Affective instability, childhood trauma and major affective disorders

“…In a relatively small study comparing healthy controls (N=20), euthymic participants with bipolar I disorder (n=16), and euthymic participants with bipolar II disorder (N=19) participants with bipolar I disorder showed abnormalities in functional and anatomical connectivity between prefrontal cortices and subcortical structures in emotion regulation circuitry. These deficits did not extend to people with bipolar II disorder, suggesting fundamental differences in the pathophysiology of bipolar disorder subtypes (Caseras et al, 2015).…”

Elucidating Neural Network Functional Connectivity Abnormalities in Bipolar Disorder: Toward a Harmonized Methodological Approach

“…Notably, other prefrontal regions are sometimes implicated, including the dorsolateral PFC (dlPFC) and superior frontal gyrus (SFG). The dlPFC may also play a role in regulating the amygdala, and there is evidence for alterations of this pathway in BD (34-36). The SFG has been identified using seeds in other PFC regions (23, 37), and thus may reflect alteration within the PFC.…”