Issn Print: 0268-1315
Publication Date: 2006/07/01
Association between genetic polymorphisms in the renin–angiotensin system and polydipsia in schizophrenia
Takahiro Shinkai; Chima Matsumoto; Osamu Ohmori; Hiroko Hori; Jun Nakamura
+ Author Information
Author Information: Department of Psychiatry, School of Medicine, University of Occupational and Environmental Health, Yahatanishi-ku, Kitakyushu 807-8555, Japan
Excerpt
The pathophysiology of polydipsia, which is frequently diagnosed in patients with chronic schizophrenia, is not yet clear. Some of the patients with polydipsia develop severe hyponatremia-related symptoms, often referred to as water intoxication. In our previous study, we have demonstrated that there may be a genetic predisposition to polydipsia and water intoxication (Shinkai et al., 2003). On the other hand, a dysfunction of the renin–angiotensin system may contribute to the pathophysiology of polydipsia in schizophrenia via chronic blockage of dopamine D2 receptors by typical antipsychotic drugs. In the present study, we investigated the genetic polymorphisms of the renin–angiotensin system, A-20C and G-6A polymorphisms in the angiotensinogen gene, the A1166C polymorphism in the angiotensin receptor type 1 (AT1) gene and the C3123A polymorphism in the angiotensin receptor type 2 (AT2) gene. These polymorphisms have been associated with essential hypertension or other cardiovascular dysfunctions, suggesting that they may play a role in the regulation of salt/water balance. We therefore hypothesized that these polymorphisms would contribute to the susceptibility to polydipsia and water intoxication in schizophrenia. We conducted case–control studies to investigate the association.
The four genetic polymorphisms were genotyped in patients with polydipsia (n=65) and in those without polydipsia (control patients n=94) using polymerase chain reaction–restriction fragment length polymorphism methods. Genotype distributions and allele frequencies were compared between patients with and without polydipsia. We also compared them between patients with water intoxication (n=33) and control patients.
No significant associations between these polymorphisms and polydipsia or water intoxication were found.
Our results suggest that the genetic polymorphisms in the renin–angiotensin system may not contributer to the pathophysiology of polydipsia and water intoxication in schizophrenia, although further studies are warranted before a conclusion can be drawn.
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