Circadian rhythms of dopamine-beta-hydroxylase and c-AMP in plasma of controls and patients with affective disorders.

In normals, dopamine-beta-hydroxylase activity in plasma follows a circadian rhythm with maximal values at 8 a.m. and minimal at 2 a.m. This pattern does not exist in affective patients in the phase of mania or normothymia, while it is present in the depressive phase. Plasma c-AMP has its maximal concentrations in plasma at 2 p.m. and its minimal at 2 a.m. in normals. In affective patients the minimum occurs at 2 a.m., as in normals, while the maximum is shifted 6 hours earlier, at 8 a.m., independently of the phase of the illness. During the depressive phase, the circadian rhythms of dopamine-beta-hydroxylase and c-AMP in plasma are synchronized.