title: Brain structural changes and neuropsychological impairments in male polydipsic schizophrenia.
abstract: BACKGROUND
  Polydipsia frequently occurs in schizophrenia patients. The excessive water loading in polydipsia occasionally induces a hyponatremic state and leads to water intoxication. Whether polydipsia in schizophrenic patients correlates with neuropsychological impairments or structural brain changes is not clear and remains controversial.
  
  
  METHODS
  Eight polydipsic schizophrenia patients, eight nonpolydipsic schizophrenia patients, and eight healthy controls were recruited. All subjects underwent magnetic resonance imaging (MRI) and neuropsychological testing. Structural abnormalities were analyzed using a voxel-based morphometry (VBM) approach, and patients' neuropsychological function was assessed using the Brief Assessment of Cognition in Schizophrenia, Japanese version (BACS-J).
  
  
  RESULTS
  No significant differences were found between the two patient groups with respect to the clinical characteristics. Compared with healthy controls, polydipsic patients showed widespread brain volume reduction and neuropsychological impairment. Furthermore, the left insula was significantly reduced in polydipsic patients compared with nonpolydipsic patients. These nonpolydipsic patients performed intermediate to the other two groups in the neuropsychological function test.
  
  
  CONCLUSIONS
  It is possible that polydipsia or the secondary hyponatremia might induce left insula volume reduction. Furthermore, this structural brain change may indirectly induce more severe neuropsychological impairments in polydipsic patients. Thus, we suggest that insula abnormalities might contribute to the pathophysiology of polydipsic patients.
authors.affiliation: Department of Psychiatry, Nara Medical University, Kashihara, Nara, Japan. tomo-n@nirs.go.jp
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Nagashima
authors.forename: Makoto
authors.initials: M
authors.lastname: Inoue
authors.forename: Soichiro
authors.initials: S
authors.lastname: Kitamura
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Kiuchi
authors.forename: Jun
authors.initials: J
authors.lastname: Kosaka
authors.forename: Koji
authors.initials: K
authors.lastname: Okada
authors.forename: Naoko
authors.initials: N
authors.lastname: Kishimoto
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Taoka
authors.forename: Kimihiko
authors.initials: K
authors.lastname: Kichikawa
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Kishimoto
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology* / Q000503:physiopathology; D002540:Cerebral Cortex / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007010:Hyponatremia / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D059607:Polydipsia, Psychogenic / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia / Q000150:complications / Q000473:pathology / Q000503:physiopathology