Plasma and red blood cell thiamine deficiency in patients with dementia of the Alzheimer's type
M. Gold, M. F. Chen and K. Johnson
Department of Neurology, University of South Florida College of Medicine, Tampa, USA.
OBJECTIVES: To determine the prevalence of plasma thiamine deficiency in
patients referred to a memory disorder clinic and to compare plasma
thiamine levels with red blood cell (RBC) thiamine levels. To determine if
patients with senile dementia of the Alzheimer's type (SDAT) differ from
those without SDAT in either plasma or RBC thiamine levels. DESIGN:
Case-control study. SETTING: Ambulatory care referral center. PATIENTS:
Consecutive sample of 34 patients; 17 patients who met the National
Institute of Neurological and Communicative Disorders and
Stroke-Alzheimer's Disease and Related Disorders Association criteria for
probable Alzheimer's disease and 17 patients with other forms of dementia.
METHODS: Plasma and RBC thiamine levels were determined in all patients
with the use of a microbiologic assay known for its specificity to
biological forms of thiamine. Vitamin supplementation was determined by
chart review. OUTCOME MEASURES: Plasma and RBC thiamine levels. RESULTS:
Patients with SDAT were found to have significantly lower plasma thiamine
levels than patients without SDAT. Low plasma thiamine levels were detected
in a significantly larger proportion of patients with SDAT than in patients
without SDAT. Red blood cell thiamine levels did not correlate with the
clinical diagnosis of SDAT. Vitamin supplementation did not correlate with
diagnosis and plasma or RBC thiamine levels. CONCLUSIONS: A significant
proportion of patients with SDAT may have a thiamine deficiency, which may
have an impact on cognitive function. Currently used assays may not be
adequate to assess thiamine status.