- We have shown that SCZ patients show higher GH responses to APO than do normals but only on certain occasions when studied longitudinally. GH responses tend to be exaggerated at the time of relapse, and during remission may be blunted or exaggerated. Only patients who at some time demonstrate incoherent thinking and formed delusions, have exaggerated GH responses. Resting serum PRL varies in some patients much more than in normal controls and tends to decline to very low levels at the time of relapse. Several possible sources of variance remain to be controlled. However, it is tempting to infer that the instability of GH responses and resting PRL levels may signify instability in the regulation of these hormones by DA.