Patients with bipolar disorder I respond to neutral and negative stimuli less accurately than do first-degree relatives of bipolar patients or a control group, Dr. Gianna Sepede and her associates report.
The investigators recruited euthymic bipolar I outpatients, unrelated first-degree relatives of bipolar I subjects, and controls aged 18-55 years. Other than age, the inclusion criteria were right-handedness and an IQ of greater than 70.
Participants were shown colored pictures from the International Affective Picture System . Stimuli generated by a computer were projected over a screen. The participants were told to press a “yes” or “no” button when they were able to see items such as plants and flowers inside neutral or negative pictures on the screen. They were asked to rate the unpleasantness of negative stimuli on a range of 1 (not unpleasant at all) to 9 (extremely unpleasant).
Both the group of first-degree relatives and the control group were about 6% more accurate than was the BD-I group when responding to both neutral and negative stimuli; overall accuracy stood at 87% for the group of relatives and control group and 81% for the BD-I group. In addition, no significant difference was found in response time, with the group of relatives actually having a slightly slower response time than did those in the BD-I group (1,084 milliseconds vs. 1,073 milliseconds vs. 1,036 milliseconds for control group).
A potential explanation for the findings is that “unaffected relatives of BD-I succeeded in maintaining a good “overt” behavioral performance (to correctly identify “targets”) through a high activation of prefrontal areas during neutral stimuli. As a consequence, diminished prefrontal resources were available for the “covert” processing of negative emotions, and occipital regions were hyperactivated to compensate this deficit,” the investigators said, cautioning that this conclusion was still speculative.
Find the full study in Progress in Neuro-Psychopharmacology & Biological Psychiatry (doi: 10.1016/j.pnpbp.2015.01.016).