Circadian rhythm of vital signs, norepinephrine, epinephrine, thyroid hormones, and cortisol in schizophrenia.

Changes in the circadian rhythmicity in vital signs, catecholamines, thyroid hormones, and cortisol have been observed in psychiatric disorders, most notably in depression. With respect to schizophrenia, the literature is scanty. We report here on the circadian parameter estimates of the vital signs, epinephrine, norepinephrine, triiodothyronine, thyroxine, thyroid stimulating hormone, and cortisol in the blood of 34 healthy subjects, 89 drug-free schizophrenic patients, and 25 neuroleptic-treated schizophrenic patients. The analyses are based on the cosine model to fit the experimental data. The circadian profiles of heart rate, blood pressure, and oral temperature are similar among schizophrenic patients and healthy subjects. Neuroleptic-treated patients have significantly higher MESORs (the daily mean) of serum norepinephrine and epinephrine than healthy subjects. The TSH MESOR is significantly lower in schizophrenic patients; the MESOR of triiodothyronine also shows a tendency to be nonsignificantly lower in schizophrenic patients compared with control subjects. The circadian serum thyroxine and cortisol profiles are similar in the three groups. The data show that the circadian profiles of vital signs in drug-free chronic schizophrenic patients who are not chronically hospitalized are similar to those of healthy subjects and that the increase in serum catecholamines and the apparent lowering in some thyroid indices might induce a down-regulation in the noradrenergic receptor system that could contribute to the pathophysiology of schizophrenia.