Several findings emerge from this study. First, prior to MBCT brain activity in BD was greater over the frontal and cingulate cortex during resting eyes closed, which suggests decreased attentional readiness, MBCT improved attentional readiness slightly. Second, prior to MBCT brain activation in BD showed activation of non-relevant information processing over the frontal cortex, MBCT attenuated activation of this non-relevant information processing.
Brain activity prior to MBCT, individuals with BD showed decreased attentional readiness, as theta activity was decreased, beta activity was increased, and theta/beta ratios was decreased over the frontal (F3 & F4) and cingulate (C3 & C4) cortices during resting eyes closed. Increased anterior and frontal midline theta has been positively correlated with internalized attention and positive emotional state, in experienced mediators during rest [25
]. During attentional processes frontal theta activity is suggested to originate from the functional connectivity between the frontal cortex and anterior cingulate cortex [26
] and serves to maintain attentional processes [27
], which is lacking in BD [2
]. Furthermore increased beta activity during eyes closed has been referred to as an index of spontaneous cognitive operations of these similar brain areas, and several others areas [28
]. In hand, a recent study related increased theta/beta ratios to mechanisms of approach [29
]. The present data suggests that individuals with BD have deficits in resting brain activity, which may decrease their abilities to attend to relevant information, and therefore lack attentional readiness. Post MBCT intervention individuals with BD showed a slight improvement in attentional readiness, as right frontal EEG activity improved, beta activity was decreased and there was a tendency for theta and theta/beta ratios to increase. The present resting data supports the literature, that BD has 'weak' regulation of behavioral systems that are required for attentional processes [13
]. MBCT intervention in BD may serve to improve attentional readiness.
Brain activation prior to MBCT individuals with BD showed activation of non-relevant information processing over the frontal cortex, as controls did not require this information processing. During the cueing process of the continuous performance task (letter A) individuals with BD showed a prominent P300-like wave form over the frontal (F3 & F4) cortices. This P300-like wave form persisted during the target but did not reach significance. Source analysis of frontal P300 wave forms has been attributed to extended cortical networks, unlike the parietal P300 wave form, at the temporal parietal junction [30
]. The cueing process may assist BD by permitting activation of compensatory mechanisms, being the activation of working memory in the present attentional task [2
]. Post MBCT intervention individuals with BD showed attenuated P300-like wave form over the frontal cortices. This suggests MBCT attenuated the interfering or previously required compensatory information processing brain mechanisms in BD individuals.
A number of limitations should be noted. First given the small size, we cannot determine whether some of the negative findings are false negatives, the trends towards statistical significance here may reach significance with larger sample. Second, the effect of medication on brain wave activity and/or activation were not included in the analysis, nevertheless medications were stable prior and post MBCT intervention Third, the control group did not undergo MBCT, which limits our understanding in the effects of MBCT on brain activity and activation. Fourth, no control bipolar group was included in the presented data, future studies would benefit with inclusion of a control bipolar group. Fifth, we had intended to have a gender balanced group, however during the recruitment process, mostly women volunteered, which limits the generalizability of the present study.