Serotonin 5-HT 1A receptor binding in people with panic disorder : positron emission tomography study

Background: The importance of the neurotransmitter serotonin (5-HT) in the pathophysiology of anxiety is well known. A key role for postsynaptic 5-HT1A receptors has recently been suggested in studies of genetic knockout mice. Aims: To measure 5-HT1A receptor binding in patients with panic disorder in the untreated state and after recovery on treatment with selective serotonin reuptake inhibitors (SSRIs). Method: Nine symptomatic untreated patients with panic disorder, seven patients recovered on SSRI medication and nineteen healthy volunteers underwent a single positron emission tomography (PET) scan using the 5-HT1A tracer [11C]WAY-100635. Results: In comparison with controls, both presynaptic and postsynaptic 5-HT1A receptor binding was reduced in untreated patients, with the most significant reductions being in the raphe, orbitofrontal cortex, temporal cortex and amygdala. In recovered patients presynaptic binding was reduced, but there was no significant reduction in postsynaptic binding. Conclusions: Panic disorder is associated with reduced 5-HT1A receptor availability, which is also known to have a key role in depression.