A brain chemical recently found to boost trust appears to work by reducing activity and weakening connections in fear-processing circuitry, a brain imaging study at the National Institutes of Health's (NIH) National Institute of Mental Health (NIMH) has discovered. Scans of the hormone oxytocin's effect on human brain function reveal that it quells the brain's fear hub, the amygdala, and its brainstem relay stations in response to fearful stimuli. The work at NIMH and a collaborating site in Germany suggests new approaches to treating diseases thought to involve amygdala dysfunction and social fear, such as social phobia, autism, and possibly schizophrenia, report Andreas Meyer-Lindenberg, M.D., Ph.D., NIMH Genes Cognition and Psychosis Program, and colleagues, in the December 7, 2005 issue of the Journal of Neuroscience.

"Studies in animals, pioneered by now NIMH director Dr. Thomas Insel, have shown that oxytocin plays a key role in complex emotional and social behaviors, such as attachment, social recognition and aggression," noted NIH Director Elias Zerhouni, M.D.. "Now, for the first time, we can literally see these same mechanisms at work in the human brain."

"The observed changes in the amygdala are exciting as they suggest that a long-acting analogue of oxytocin could have therapeutic value in disorders characterized by social avoidance," added Insel.

Inspired by Swiss scientists who last summer reported [1] that oxytocin increased trust in humans, Meyer-Lindenberg and colleagues quickly mounted a brain imaging study that would explore how this works at the level of brain circuitry. British researchers had earlier linked increased amygdala activity to decreased trustworthiness. [2] Having just discovered decreased amygdala activity in response to social stimuli in people with a rare genetic brain disorder that rendered them overly trusting of others, Meyer-Lindenberg hypothesized that oxytocin boosts trust by suppressing the amy
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Contact: Jules Asher
NIMHpress@nih.gov
301-443-4536
NIH/National Institute of Mental Health
7-Dec-2005

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