Of the initial 51 participants (24 controls and 27 depressed at time-1) (Fales et al., 2008
), 41 returned at time-2 (18 controls and 23 depressed). All time-1 effects were significant both for the original sample (n=51) and for the reduced sample (n=41). There were no significant differences in depression or anxiety scores between the 18 controls who returned at time-2 and the six controls who did not, nor between the 23 patients who returned and the four patients who did not (independent t-tests, all p
After eight weeks of antidepressant therapy, 14 out of the 23 depressed subjects achieved 89% reduction or better in depressive symptoms, as measured on the HDRS scale. Seven showed 50-88% improvement, and the remaining two showed 43-49% reductions. Thus in our sample, approximately half the sample showed a very significant improvement in symptoms, and all patients responded at least partially to treatment.
At time-1, depressed patients were significantly slower than controls, but no less accurate. At time-2, the patients showed a modest but non-significant improvement in response time. (See Supplementary Information
for details of behavioral data.)
Neuroimaging results: DLPFC
At time-1, a right DLPFC region showed a 3-way interaction between group, attention (attended, ignored) and emotion (fear, neutral) F(1,39) = 5.44, p=.03, η2=.122. When ignoring fearful faces (versus ignore-neutral), depressed patients were significantly less activated than controls, t(39)=2.28, p=.028, η2=.12 (uncorrected) but not in the attend condition, p=.17. To assess change after treatment, we conducted a four-way ANOVA with time (pre-treatment, post-treatment) as an additional factor. The right DLPFC did not show a significant four-way interaction, p=.17. However the depressed patients showed a significant increase in DLPFC activity in the ignore-fear versus ignore-neutral comparison from time 1 to time-2, F(1,22)=6.21, p=.02, η2=.220. In contrast, the controls' DLPFC activity for ignore-fear minus ignore-neutral did not change significantly from time-1 to time-2, F(1,17)=2.10, p>.16, η2=.110.
Neuroimaging results: Amygdala
At time-1, a left amygdala region had also showed a 3-way interaction between group, attention and emotion, F(1,39) = 7.20, p=.011, η2=.156. When ignoring fearful faces (versus ignore-neutral), depressed patients were significantly more activated than controls, F(1,39) = 4.31, p=.045, η2=.099, but significantly less activated for the same contrast in the attend condition, F(1,39) = 4.94, p=.03, η2=.112. Incorporating time-2 data into the ANOVA, the left amygdala () showed a significant four-way interaction, F(1,39) = 4.056, p=.05, η2=.094, because the significant three-way interaction at time-1 disappeared at time-2, p>.3. By time-2, amygdala activation for the fear-minus-neutral contrast in the depressed was no longer different from that of controls at time-2 (both ps>.4), nor did they differ from control values at time-1, (ps>.7). However paired t-tests for the depressed patients alone did not reveal significant reductions in amygdala activity at time-2 in response to ignore-fear trials (versus ignore-neutral), F(1,22)=6.21, p=.02, η2=.220.
Figure 1 Fear-minus-neutral activity in the right dorsolateral prefrontal cortex and left amygdala. These regions showed a significant three-way interaction of attention × emotion × group at time-1. The graphs show percent change in signal magnitude. (more ...)
Four other regions showed significant group-related effects at time-1, but these effects were not normalized at time-2. These regions were the 1) subgenual cingulate, 2) pregenual cingulate, 3) an area spanning dorsal/rostral cingulate, and 4) the dorsal cingulate. These effects (summarized in ) are described in more detail in the Supplemental Information
We tested whether HDRS scores in the patients at time-2 were related to their time-2 activation values for the ignore-fear-minus-ignore-neutral contrast, or whether the percent change in HDRS scores across time was related to activation changes in the ignore-fear-minus-ignore-neutral contrast across time. Similar to time-1, there was no relationship between HDRS scores at time-2 and activation values at time-2, nor between the improvement in HDRS scores across time and changes in ignore-fear contrasts for left amygdala or right DLPFC, all ps >.1.