Objective: To examine plasma cortisol, adrencorticotropin hormone, and indicators of catecholamine activity in monozygotic twins discordant for schizophrenia or major affective disorders.
Background: Previous research has suggested that catecholamines play a role in the etiology of major mental illness. Several findings have also shown an inverse relation between hippocampal volume and cortisol levels in psychiatric populations including patients who are depressed and patients with Cushing disease.
Method: In this study, plasma obtained from monozygotic twin pairs discordant for schizophrenia (n = 10) or major affective disorder (n = 3) was assayed for epinephrine, norepinephrine, dihydroxyphenylacetic acid, homovanillic acid, adrencorticotropin hormone, and cortisol.
Results: There was significant concordance for levels of dihydroxyphenylacetic acid and homovanillic acid, consistent with the high concordance for indicators of dopamine activity observed in healthy monozygotic pairs. There was also concordance for adrencorticotropin hormone. However, in contrast to findings on healthy monozygotic pairs, there was no relation for epinephrine, norepinephrine, or cortisol. Among patients, there was an inverse correlation between cortisol and the magnitude of the reduction in hippocampal volume, relative to that of the healthy co-twin.
Conclusion: These findings suggest the potential role of adrenal steroids and hippocampal function in the expression of psychosis.