1. 1. Psychiatric patients presenting with chronic psychogenic polydipsia are often difficult to treat with standard psychiatric interventions. 2. 2. Pharmacologie intervention was attempted in three patients and was successful in one. 3. 3. One patient had a significant and sustained reduction of water intake while on 160 mg of propranolol. 4. 4. One patient did not improve with either propranolol or captopril while a third patient showed no improvement of serum sodium with demeclocycline nor reduction of water intake with propranolol. 5. 5. The potential mechanisms by which these pharmacologic agents might alter thirst in patients with primary polydipsia are discussed.

Glucocorticoids are used for many purposes in veterinary medicine but often come with significant adverse effects. Polyuria and polydipsia are the most common adverse effects noted by owners. To determine whether administration of desmopressin ameliorated the polyuria and polydipsia, a prospective study with 7 healthy Walker Hounds was performed. Daily water intake and urine specific gravity were measured in dogs under 4 separate conditions: no medications, prednisolone only, prednisolone and desmopressin, and prednisolone immediately after discontinuation of desmopressin. When compared to baseline, six out of seven dogs became polydipsic after administration of prednisolone twice daily. When desmopressin was administered to dogs receiving prednisolone, there was a statistically significant decrease in water intake and sodium concentration, and a significant increase in urine specific gravity. This suggests that desmopressin ameliorates the most significant side effect of prednisolone noted by owners, but that hyponatremia is an important complication associated with desmopressin.

Primary polydipsia, excessive drinking without known medical cause, continues to occur with a significant prevalence in psychiatric populations. While the etiology of polydipsia remains unknown, the fact that it is significantly associated with a diagnosis of schizophrenia has led some to postulate that the two may share common neurological pathophysiologies. Animal models of schizophrenia-like symptoms have focused on modeling the core behavioral and neurochemical features of the illness, like cognitive deficits and enhanced dopamine transmission. Here, we used three well-established models, including repeated amphetamine treatment, subchronic MK-801 (an N-methyl-D-aspartate [NMDA]-receptor antagonist), and post-weaning social isolation. We also examined a “double-hit” model, combining NMDA-receptor antagonism and social isolation. We paired these models to test the hypothesis that drinking will be enhanced in a paradigm of excessive drinking in the rat. In rodents, non-physiologic drinking can be induced by intermittent presentation of food (e.g., one sugar-pellet a minute) in the presence of a drinking spout to a hungry animal, termed schedule-induced polydipsia (SIP). Animals pretreated with pharmacological or non-pharmacological models of schizophrenia-like symptoms showed significantly increased SIP, The “double hit” model did not further increase drinking above that of either social isolation or MK-801 treatment alone. A moderate amount of spontaneous polydipsia in the homecage of MK-801-treated rats was also observed and resulted in one death secondary to excessive drinking, a phenomenon also found in inpatients with schizophrenia. Following repeated treatment with AMPH, there was some evidence that over time, animals learned to drink increased amounts independently of the scheduled food presentation. This evidence suggests that the excessive drinking behavior observed in polydipsia associated with schizophrenia may have a learned component. In summary, animal models of schizophrenia-like symptoms augmented SIP behavior, showing that polydipsia associated with schizophrenia may be modeled in rodents. As each model has been shown to modify dopamine transmission to some degree, the evidence suggests augmented SIP may reflect changes in dopamine transmission and dopamine may be the common link between polydipsia and schizophrenia. Further research is necessary to fully elucidate the mechanisms underlying SIP, polydipsia and schizophrenia. / Thesis (Ph.D, Neuroscience Studies) -- Queen's University, 2012-10-31 17:43:18.34

Falk's pivotal 1961 study showed that rats would drink excessive amounts of water when exposed to a time based schedule of reinforcement. Since then, schedule-induced drinking or polydipsia, has been demonstrated with several species and with a variety of different behaviors. Rats, the most commonly used animal, have been shown to drink excessive amounts of water under a variety of different time based schedules of reinforcement; exclusively during a free operant procedure. The current study shows that water drinking can be induced during a discrete trial procedure, and instead of using a time-based schedule of reinforcement, this study used a variable-ratio schedule of reinforcement. The results showed that excessive water drinking was induced under these conditions with a canine.