Objective
Major depression in adolescents is a significant public health concern because of its frequency and severity. To examine the neurobiological basis of depression in this population, the authors studied functional activation characteristics of the brain before and after antidepressant treatment in antidepressant-naive depressed adolescents and healthy comparison subjects.
Method
Depressed (N=19) and healthy (N=21) adolescents, ages 11 to 18 years, underwent functional MRI assessment while viewing fearful and neutral facial expressions at baseline and again 8 weeks later. The depressed adolescents received 8 weeks of open-label fluoxetine treatment after their baseline scan.
Results
Voxel-wise whole brain analyses showed that depressed youths have exaggerated brain activation compared with healthy comparison subjects in multiple regions, including the frontal, temporal, and limbic cortices. The 8 weeks of fluoxetine treatment normalized most of these regions of hyperactivity in the depressed group. Region-of-interest analyses of the areas involved in emotion processing indicated that before treatment, depressed youths had significantly greater activations to fearful relative to neutral facial expressions than did healthy comparison subjects in the amygdala, orbitofrontal cortex, and subgenual anterior cingulate cortex bilaterally. Fluoxetine treatment decreased activations in all three regions, as compared with the repeat scans of healthy comparison subjects.
Conclusions
While effective treatments are available, the impact of depression and its treatment on the brain in adolescents is understudied. This study confirms increases in brain activation in untreated depressed adolescents and demonstrates reductions in these aberrant activations with treatment.
We used functional magnetic resonance imaging (fMRI) to study semantic memory processing in 38 Gulf War veterans in 3 affected groups (Syndromes 1, 2, and 3) and normal-deployed controls. Subjects were given the Semantic Object Retrieval Test (SORT), which requires participants to decide whether two features combine and result in the retrieval of a specific object (e.g., "desert" and "humps" → "camel"). Differences between groups were calculated using a repeated measures analysis of variance (ANOVA). Then, regions of interest were constructed and correlations assessed between the percent signal change (PSC) within these regions, followed by correlations between behavioral measures and PSC. We found affected groups performed less well on the SORT than the controls did, and behavioral differences were correlated to PSC within the caudate and thalamus. The combination of performance deficits and functional neuroimaging differences between affected Gulf War veterans and deployed normal controls begins to establish a neurobiological basis for their word-finding deficits.
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