Diurnal weight gain in chronic psychosis

We found diurnal weight gain to be abnormal among 93 chronically psychotic patients, most of whom had schizophrenia. They were weighed at 7 a.m. and 4 p.m. weekly for 3 weeks. We normalized the diurnal weight gain (NDWG) as a percentage by subtracting the 7 a.m. weight from the 4 p.m. weight, multiplying the difference by 100, and dividing the result by the 7 a.m. weight. NDWG was 1.7 +/- 1.0 percent for the study sample, 0.6 +/- 0.4 percent for 16 acutely psychotic controls, and 0.5 +/- 0.4 percent for 29 normals. More than 60 percent of the study sample had abnormal NDWG values. NDWG related to antipsychotic drug dose (r = 0.290, p = 0.005) with variability in drug dose accounting for 8 percent of the variability in NDWG. This report provides yet another piece of evidence that disordered water balance is common in chronic psychiatric patients. The etiology is unknown, but it may relate to subtle brain abnormalities in the regulation of fluid intake and excretion.