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29-04-2015 | Bipolar disorder | Article

Emotion regulation deficits specific to bipolar I disorder

medwireNews: Emotion regulation deficits associated with bipolar I disorder (BD-I) may not extend to bipolar II disorder (BD-II), say researchers.

Both groups showed increased emotional reactions during an attention control task in the presence of emotional distractors, but while in BD-I patients there was evidence of behavioural, functional connectivity and white matter microstructure deficits, this was not the case for BD-II patients.

The findings “emphasize deficient emotion regulation in the pathophysiology of the disorder, but suggest important differences between BD-I and BD-II in this process”, comments the team, led by Xavier Caseras (Cardiff University, UK).

The participants, comprising 16 euthymic patients with BD-I, 19 euthymic patients with BD-II and 20 mentally healthy controls, completed a 2-back working memory task, during which targets were sometimes flanked by two identical emotional facial expressions – neutral, fear or happy.

The presence of any of these emotional distractors significantly slowed the reaction times of patients with BD-I compared with healthy controls and BD-II patients, whereas there was no difference between healthy controls and BD-II patients. Most notably, the average reaction time of BD-I patients slowed significantly from approximately 680 msec when there were no distractors to 775 msec in the presence of fear distractors. For BD-II patients, there was no significant change in response time during any distractor.

Both groups of BD patients showed increased blood oxygenation level-dependent (BOLD) responses in the dorsolateral prefrontal cortex (DLPFC) and amygdala during the presence of fear distractors compared with healthy controls. But only BD-I patients showed increased inverse functional connectivity between the DLPFC and amygdala. In BD-II patients, the functional connectivity between these regions was, in fact, heightened in the presence of fear distractors.

In line with the behavioural and functional magnetic resonance imaging findings, BD-I patients showed reduced fractional anisotropy in the right uncinate fasciculus, compared with BD-II patients and healthy controls, who did not differ from each other.

“This finding further supports emotion regulation circuitry abnormalities being specific to BD-I and not generalized to BD-II”, say Caseras et al in Bipolar Disorders.

The findings indicated that “the less compromised the white matter in the uncinate fasciculus, as in subjects with BD-II relative to subjects with BD-I, the better the functional DLPFC–amygdala coupling during emotion regulation, resulting in better task performance”, they add.

By Lucy Piper

medwireNews is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2015

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