Effects of bupropion sustained release on task-related EEG alpha activity in smokers: Individual differences in drug response

Abstract

The mechanisms underlying bupropion's efficacy as an antidepressant and a smoking cessation aid are far from being fully characterized. The present study is the first to examine the effects of bupropion on visuospatial task-related parietal EEG alpha power asymmetry-an asymmetry that has previously been found to be associated with severity of depressive symptoms (i.e., the more depressive symptoms, the greater alpha power in the right vs. left parietal area [Henriques & Davidson, 1997; Rabe, Debener, Brocke, & Beauducel, 2005]). Participants, all of whom were smokers and none of whom were clinically depressed, were randomly assigned to the Placebo group (n = 79) or Bupropion group (n = 31) in a double-blind study. EEG during the performance of the visuospatial task was collected before and after 14 days on placebo or bupropion sustained-release capsules. Relative to the Placebo group, the Bupropion group (especially, the Bupropion subgroup who had a positive right versus left parietal alpha power asymmetry at pretreatment) had a reduction in the parietal alpha asymmetry (driven largely by a decrease in right parietal alpha power). These findings support the hypothesis that bupropion can induce changes in parietal EEG asymmetry that have been shown in previous literature to be associated with a reduction in depressive states and traits. (PsycINFO Database Record

Figure 1

Parietal alpha asymmetry as a function of Group and Session. There was a significant interaction between Group and Session (p = .04). The Placebo and Bupropion groups did not differ during pretreatment (p = .21). Yet the Placebo group did not change from pretreatment to post-treatment (p = .37), whereas the Bupropion group tended to have a decrease in parietal asymmetry with treatment (p = .06).

Figure 2

The same left and right parietal alpha power data from Table 2 but without the natural logarithm transformation are plotted for easy visualization of the results.

Figure 3

The individual change of parietal alpha asymmetry from the pretreatment to post-treatment session within the Bupropion group, shown separately for participants who had a negative pretreatment asymmetry (n = 14) and who had a positive pretreatment asymmetry (n = 17). Each line represents a participant. The parietal asymmetry in the Negative Bupropion subgroup did not change with treatment, whereas the parietal asymmetry in the Positive Bupropion subgroup was significantly decreased. Because the exclusion of one outlier in the Positive Bupropion subgroup (shown at the top of the right panel) did not change the subgrouping statistical significance, the outlier was included in the subgrouping analyses reported in the text.