title: Brain type carnosinase in dementia: a pilot study.
abstract: BACKGROUND
  The pathological processes underlying dementia are poorly understood and so are the markers which identify them. Carnosinase is a dipeptidase found almost exclusively in brain and serum. Carnosinase and its substrate carnosine have been linked to neuropathophysiological processes.
  
  
  METHODS
  Carnosinase activity was measured by a flourometric method in 37 patients attending a Geriatric Outpatient Clinic. There were 17 patients without dementia, 13 had Alzheimer's disease (AD) and 7 had mixed dementia (MD).
  
  
  RESULTS
  The range of serum carnosinase activity for patients without dementia was 14.5 - 78.5 micromol/ml/h. There was no difference in carnosinase activity between patients without dementia (40.3 +/- 15.2 micromol/ml/h) and patients with AD (44.4 +/- 12.4 micromol/ml/h) or MD (26.6 +/- 15 micromol/ml/h). However, levels in the MD group were significantly lower than the AD group (p = 0.01). This difference remained significant after adjusting for gender, MMSE score, exercise, but not age, one at a time and all combined. The effect of other medical conditions did not remove the significance between the AD and MD groups. The MD group, but not the AD group, demonstrated a significant trend with carnosinase activity decreasing with duration of disease (from first recorded date of diagnosis to date of blood collection) (r = -0.76, p = 0.049). There was no association with carnosinase activity and MMSE score in the AD or MD group. Both AD and MD patients on any dementia medication (donepezil, galantamine, memantine) had higher carnosinase activity compared to those not taking a dementia medication. Carnosinase activity was higher in patients who regularly exercised (n = 20) compared to those who did not exercise regularly (n = 17)(p = 0.006).
  
  
  CONCLUSIONS
  This exploratory study has shown altered activities of the enzyme carnosinase in patients with dementia.
authors.affiliation: Department of Laboratory Medicine, Hamilton Health Sciences, Hamilton, Ontario, Canada. balion@hhsc.ca
authors.forename: Cynthia M
authors.initials: CM
authors.lastname: Balion
authors.forename: Carolyn
authors.initials: C
authors.lastname: Benson
authors.forename: Parminder S
authors.initials: PS
authors.lastname: Raina
authors.forename: Alexandra
authors.initials: A
authors.lastname: Papaioannou
authors.forename: Christopher
authors.initials: C
authors.lastname: Patterson
authors.forename: Afisi S
authors.initials: AS
authors.lastname: Ismaila
mesh_terms: D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology; D015415:Biomarkers / Q000032:analysis / Q000097:blood; D001921:Brain / Q000378:metabolism* / Q000503:physiopathology; D002336:Carnosine / Q000378:metabolism; D003704:Dementia / Q000097:blood* / Q000175:diagnosis* / Q000503:physiopathology; D004150:Dipeptidases / Q000032:analysis / Q000097:blood*; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010865:Pilot Projects; D011237:Predictive Value of Tests
chemical_list: D015415:Biomarkers; D002336:Carnosine; C522928:CNDP1 protein, human; D004150:Dipeptidases