Different neural responses to a moral valence decision task in unipolar and bipolar depression

Abstract

Objectives. Patients affected by bipolar disorder (BP) and major depressive disorder (UP) share the susceptibility to experience depression and differ in their susceptibility to mania, but clinical studies suggest that the biological substrates of the two disorders could influence the apparently similar depressive phases. The few brain imaging studies available described different brain metabolic and neural correlates of UP and BP. Methods. We studied the BOLD neural response to a moral valence decision task targeting the depressive biases in information processing in 36 subjects (14 BP, 11 UP, and 11 controls). Results. Main differences between UP and controls and between UP and BP were detected in left ventrolateral prefrontal cortex (PFC, BA 47). Neural responses of BP patients differed from those of control subjects in multiple brain areas, including anterior cingulate cortex (ACC) and medial PFC, bilateral dorsolateral PFC, temporal cortex and insula, and parietal and occipital cortex. Conclusions. Our results are in agreement with hypotheses of dysfunctions in corticolimbic circuitries regulating affects and emotions in mood disorders and suggest that specific abnormalities, particularly in ventrolateral PFC, are not the same in UP and BP depression.

Figure 1

Glass-brain images of gray matter areas where a significant effect of diagnosis and moral valence of the stimuli (negative-positive) was detected.

Figure 2

Direction and size effects of the significant interaction of diagnosis (unipolar patients versus control subjects) and moral valence of the stimuli on the event-related BOLD activations in ventrolateral PFC (BA 47, MNI coordinates –30, 40, −8). Points are estimated regression coefficients for the tasks (percent of whole brain mean T2* BOLD signal). Whiskers are standard errors.

Figure 3

Direction and size effects of the significant interactions of diagnosis (bipolar patients versus control subjects) and moral valence of the stimuli on the event-related BOLD activations in dorsolateral PFC (BA 10), Talairach coordinates 6, 2, 34), and right anterior cingulate cortex (BA 24). Points are estimated regression coefficients for the tasks (percent of whole brain mean T2* BOLD signal) before and after treatment. Whiskers are standard errors.

Figure 4

Direction and size effects of the significant interaction of diagnosis (unipolar versus bipolar patients) and moral valence of the stimuli on the event-related BOLD activations in ventrolateral PFC (BA 47, MNI coordinates –32, 32, 6). Points are estimated regression coefficients for the tasks (percent of whole brain mean T2* BOLD signal). Whiskers are standard errors.

Figure 5

Direction and size effects of the significant interaction of diagnosis (bipolar patients versus control subjects) and moral valence of the stimuli on the event-related BOLD activations in bilateral dorsolateral PFC (BA 10). Points are estimated regression coefficients for the tasks (percent of whole brain mean T2* BOLD signal). Whiskers are standard errors.