A Preliminary fMRI Study of Sustained Attention in Euthymic, Unmedicated Bipolar Disorder

Abstract

The symptoms of bipolar disorder suggest dysfunction of anterior limbic networks that modulate emotional behavior and that reciprocally interact with dorsal attentional systems. Bipolar patients maintain a constant vulnerability to mood episodes even during euthymia, when symptoms are minimal. Consequently, we predicted that, compared with healthy subjects, bipolar patients would exhibit abnormal activation of regions of the anterior limbic network with corresponding abnormal activation of other cortical areas involved in attentional processing. In all, 10 unmedicated euthymic bipolar patients and 10 group-matched healthy subjects were studied with fMRI while performing the Continuous Performance Task-Identical Pairs version (CPT-IP). fMRI scans were obtained on a 3.0 T Bruker system using an echo planar imaging (EPI) pulse sequence, while subjects performed the CPT-IP and a control condition to contrast group differences in regional brain activation. The euthymic bipolar and healthy subjects performed similarly on the CPT-IP, yet showed significantly different patterns of brain activation. Specifically, bipolar patients exhibited increased activation of limbic, paralimbic, and ventrolateral prefrontal areas, as well as visual associational cortices. Healthy subjects exhibited relatively increased activation in fusiform gyrus and medial prefrontal cortex. In conclusion, these differences suggest that bipolar patients exhibit overactivation of anterior limbic areas with corresponding abnormal activation in visual associational cortical areas, permitting successful performance of an attentional task. Since the differences occurred in euthymia, they may represent trait, rather than state, abnormalities of brain function in bipolar disorder.

Functional magnetic resonance imaging assessment of cognitive function in childhood‐onset systemic lupus erythematosus: A pilot study

“…The CPT-IP task used in this study was designed to measure attention by requiring focus on a continuous stream of data while responding to specific stimuli, in accordance with a set of a priori instructions (59)(60)(61). The group of childhood-onset SLE patients exhibited more extensive activation than control subjects in large tracts of the fusiform gyrus and visual associative cortex, regions associated, in previous research, with abnormal attention (62,63). These results suggest that functional changes in these brain areas underlie attentional changes experienced in childhoodonset SLE.…”

The phenotypes of bipolar disorder: relevance for genetic investigations

“…255 Euthymic, unmedicated bipolar patients exhibited more activation in emotional brain regions (parahippocampus/amygdale, ventrolateral prefrontal cortex) than healthy controls during the continuous performance task. 256 Malhi et al studied depressed bipolar 257 and hypomanic patients 258 during cognitive generation of affect. In contrast with healthy or unipolar depressed patients, bipolar subjects recruited subcortical brain regions (caudate, thalamus, amygdala) during emotional evaluation.…”

Increased Anterior Cingulate/Medial Prefrontal Cortical Glutamate and Creatine in Bipolar Depression

“…Additional neuroimaging findings in bipolar disorder in these regions included reduced volume of superior frontal cortex (Lopez-Larson et al, 2002), (left-sided) reduced activation of medial frontal cortex (Strakowski et al, 2004), increased regional blood flow of left aMCC (Blumberg et al, 2000;Rubinsztein et al, 2001), correlations of glucose metabolic rate in medial prefrontal cortex with clinical depression severity , posttreatment regional blood flow response to transcranial magnetic stimulation in left aMCC and medial prefrontal cortex , and increased levels of myoinositol (mI) and choline compounds (Cho) in anterior cingulate Moore et al, 2000c).…”