BACKGROUND: Many studies have found disturbances of serotonin (5-HT) activity in 
anorexia nervosa (AN). Because little is known about 5-HT receptor function in 
AN, positron emission tomography (PET) imaging with 5-HT receptor-specific 
radioligands was used to characterize 5-HT1A and 5-HT2A receptors.
METHODS: Fifteen women ill with AN (ILL AN) were compared with 29 healthy 
control women (CW); PET and [11C]WAY100635 were used to assess binding potential 
(BP) of the 5-HT1A receptor, and [18F]altanserin was used to assess postsynaptic 
5-HT2A receptor BP. [15O] water and PET were used to assess cerebral blood flow.
RESULTS: The ILL AN women had a highly significant (30%-70%) increase in 
[11C]WAY100635 BP in prefrontal and lateral orbital frontal regions, mesial and 
lateral temporal lobes, parietal cortex, and dorsal raphe nuclei compared with 
CW. The [18F]altanserin BP was normal in ILL AN but was positively and 
significantly related to harm avoidance in suprapragenual cingulate, frontal, 
and parietal regions. Cerebral blood flow was normal in ILL AN women.
CONCLUSIONS: Increased activity of 5-HT1A receptor activity may help explain 
poor response to 5-HT medication in ILL AN. This study extends data suggesting 
that 5-HT function, and, specifically, the 5-HT2A receptor, is related to 
anxiety in AN.