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.