P. S. MUELLER, in 1961, examined the plasma free fatty acid (FFA) response of chronic schizophrenics to I.M. insulin. In a preliminary study of 12 patients and seven normal controls,1 Mueller found differences in the responsivity of the two groups. The normals had a significant fall in plasma FFA but the schizophrenics did not. In fact, it was noted that three of the patients had apparent paradoxical responses to insulin in that there was no change or a rise in FFA levels.
A repetition of the study1 with an increased number of controls confirmed the findings of the first experiment so that Mueller decided to modify the experimental design2 using the standard intravenous insulin tolerance test. Ten patients and ten controls were studied; plasma FFA was measured at 0, 15, 30, and 45 minutes. This time however, the schizophrenics differed from normals only at 45 minutes.
SICKLE GRV, McCluer RH, KISTLER CR, Besch NF. Epinephrine and Insulin EffectsI. Glucose and Plasma Free Fatty Acid. Arch Gen Psychiatry. 1966;14(3):284–286. doi:10.1001/archpsyc.1966.01730090060009