Background
The amygdala is believed to play a key role in processing emotionally salient, threat-relevant,
events that require further online processing by cortical regions. Emotional disorders
such as depression and anxiety have been associated with hyperactivity of the amygdala,
but it is unknown whether antidepressant treatment directly affects amygdala responses
to emotionally significant information.
Methods
The current study assessed the effects of 7 days administration of the selective serotonin
reuptake inhibitor (SSRI), citalopram, on amygdala responses to masked presentations
of fearful and happy facial expressions in never-depressed volunteers using blood
oxygenation level-dependent (BOLD) functional magnetic resonance imaging. A double-blind,
between-groups design was used with volunteers randomized to 20 mg/day citalopram
versus placebo.
Results
Volunteers receiving citalopram showed decreased amygdala responses to masked presentations
of threat compared with those receiving placebo. Citalopram also reduced responses
within the hippocampus and medial prefrontal cortex (mPFC) specifically during the
fear-relevant stimuli. These neural differences were accompanied by decreased recognition
of fearful facial expressions assessed after the scan. By contrast, there was no effect
of citalopram on the neural or behavioral response to the happy facial expressions.
Conclusions
These results suggest a direct effect of serotonin potentiation on amygdala response
to threat-relevant stimuli in humans. Such effects may be important in the therapeutic
actions of antidepressants in depression and anxiety.
Key Words
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Article info
Publication history
Published online: February 06, 2006
Accepted:
October 7,
2005
Received in revised form:
September 8,
2005
Received:
April 21,
2005
Identification
Copyright
© 2006 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
