Tyramine conjugation deficit in patients with chronic idiopathic temporomandibular joint and orofacial pain.

This study was carried out to explore the value of the tyramine conjugation test, an established trait marker for 'endogenous unipolar depression', in patients with chronic idiopathic temporomandibular joint and orofacial pain. Our results show that the pain patients excrete significantly lower amounts of tyramine sulphate than controls (P < 0.0004). Psychiatric assessment by the structured clinical interview for the diagnosis of mental disorders according to DSM-III-R revealed that 48% of the patients had a history of depression and 10% were currently depressed. However, the never-depressed group of patients had the lowest tyramine sulphate excretion values. These findings suggest that a common biological abnormality underlies the pathogenesis of both chronic idiopathic facial pain and depression.