title: Niacin subsensitivity is associated with functional impairment in schizophrenia.
abstract: OBJECTIVE
  Sensitivity to the skin flush effect of niacin is reduced in a portion of patients with schizophrenia. Though this peripheral physiological abnormality has been widely replicated, its relevance to neuropsychiatric manifestations of the illness has been unclear. The goal of this study was to determine if the niacin response abnormality in schizophrenia is associated with functional impairment.
  
  
  METHODS
  Following psychiatric assessment, a Global Assessment of Functioning (GAF) score was assigned to each of 40 volunteers with schizophrenia. For each subject, the blood flow responses to several concentrations of topical methylnicotinate were recorded. Blood flow was measured objectively, using laser Doppler flowmetry. From the dose-response data, EC(50) values were derived. GAF scores were assigned without knowledge of the participants' niacin response data.
  
  
  RESULTS
  There was a significant negative correlation between GAF scores and EC(50) values for methylnicotinate (Pearson r=-0.42; p=0.007).
  
  
  CONCLUSIONS
  Reduced niacin sensitivity is associated with greater functional impairment among patients with schizophrenia. These findings raise the possibility that a subset of schizophrenia patients possesses a biochemical abnormality that reduces niacin sensitivity in the skin and contributes to functional impairment from the disease.
authors.affiliation: Behavioral Health and Clinical Neurosciences Division, Portland VA Medical Center, Portland, OR 97239, USA. Erik.Messamore@va.gov
authors.forename: Erik
authors.initials: E
authors.lastname: Messamore
mesh_terms: D000279:Administration, Cutaneous; D000328:Adult; D004305:Dose-Response Relationship, Drug; D005260:Female; D005483:Flushing / Q000139:chemically induced / Q000378:metabolism; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D009525:Niacin / Q000008:administration & dosage; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia / Q000175:diagnosis* / Q000503:physiopathology*; D012867:Skin / Q000098:blood supply / Q000187:drug effects*; D013223:Statistics as Topic
chemical_list: D009525:Niacin