title: Increased platelet intracellular calcium ion concentration is specific to bipolar disorder.
abstract: BACKGROUND
  Increased baseline ([Ca(2+)]B) and agonist-stimulated ([Ca(2+)]s) free intracellular calcium ion concentrations ([Ca(2+)]i) are well-replicated findings in bipolar disorder, but whether this finding is specific to that condition and if so, whether it is a marker of the mood disorder or a feature seen in other disorders such as psychosis has remained unclear.
  
  
  METHODS
  Platelet [Ca(2+)]i was assessed in 15 inpatients with psychotic and nonpsychotic mania, 17 schizophrenia inpatients, and 17 matched controls.
  
  
  RESULTS
  Platelet [Ca(2+)]B and [Ca(2+)]s were significantly higher than controls in bipolar disorder but not schizophrenia. Variability of [Ca(2+)]B was significantly increased in bipolar disorder regardless of the presence of psychosis, but not in schizophrenia.
  
  
  CONCLUSIONS
  Use of antipsychotic drugs by the majority of both patient groups may have obscured elevated [Ca(2+)]i in schizophrenia, or may have masked a difference between psychotic and nonpsychotic bipolar disorder. Measurement of [Ca(2+)]i is too labor intensive to become a routine test for diagnosis or prediction of treatment response.
  
  
  CONCLUSIONS
  Elevated intracellular Ca(2+) signaling may be a marker of primary cellular hyperactivity that could contribute to comorbid conditions such as hypertension and neuronal apoptosis. Since lithium and carbamazepine attenuate increased [Ca(2+)]i, further research may demonstrate a correlation between normalization of [Ca(2+)]i and response to one of these medications, and further research may clarify whether a subgroup of patients may respond well to calcium channel antagonists.
authors.affiliation: Department of Psychiatry, State University of New York at Buffalo, Buffalo, NY 14215, USA; Departments of Psychiatry and Medicine, University of Colorado, Denver, CO, USA. Electronic address: dubovsky@buffalo.edu.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Dubovsky
authors.affiliation: Department of Psychiatry, State University of New York at Buffalo, Buffalo, NY 14215, USA.
authors.forename: Elsa
authors.initials: E
authors.lastname: Daurignac
authors.affiliation: Department of Psychiatry, State University of New York at Buffalo, Buffalo, NY 14215, USA; Research Institute on Addictions, University at Buffalo, Buffalo, NY, USA.
authors.forename: Kenneth E
authors.initials: KE
authors.lastname: Leonard
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000627:therapeutic use; D015415:Biomarkers / Q000097:blood; D001714:Bipolar Disorder / Q000097:blood* / Q000175:diagnosis / Q000188:drug therapy / Q000523:psychology; D001792:Blood Platelets / Q000378:metabolism*; D002118:Calcium / Q000097:blood*; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011618:Psychotic Disorders / Q000097:blood; D012559:Schizophrenia / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy; D014635:Valproic Acid / Q000627:therapeutic use; D055815:Young Adult
chemical_list: D014150:Antipsychotic Agents; D015415:Biomarkers; D014635:Valproic Acid; D002118:Calcium
keywords: Bipolar disorder; Intracellular calcium; Platelet; Schizophrenia