Agoraphobia and the dexamethasone suppression test: atypical depression?

The tricyclic antidepressants and the monoamine oxidase inhibitors have been shown to be effective in the treatment of some patients with phobic and panic disorders. To explain this action it has been suggested that a number of these patients may have an atypical biological depression. In an attempt to test this hypothesis we used the dexamethasone suppression test (DST), which has been proposed as a state dependent biological marker of depression. We compared the non-suppression rate of agoraphobic patients suffering panic attacks with controls and with patients suffering major depression. Twenty-nine per cent of the agoraphobics showed non-suppression compared with 12% of the control group and 64% of the depressives.