To investigate a possible association between disordered water homeost
asis and cognitive impairment in schizophrenia, neuropsychological tes
ts were applied to 16 schizophrenic patients with severely deranged wa
ter homeostasis and to 16 matched schizophrenic controls. The patients
with disordered water homeostasis tended to obtain poorer scores than
the controls throughout, the differences being statistically signific
ant for two of the tests (Wechsler Memory Scale Visual Reproduction an
d Trail Marking Test part A). These results were not ascribable to dif
ferences in the duration of the illness, premorbid IQ, medication, or
electroconvulsive therapy received, or prominence of any particular sy
mptoms. The results suggest the co-existence of disordered water homeo
stasis and cognitive impairment in a subset of schizophrenic patients.