CSF TAU IS RELATED TO APOLIPOPROTEIN-E GENOTYPE IN EARLY ALZHEIMERS-DISEASE

We quantified microtubule-associated protein tau in CSF (CSF tau) usin g ELISA assay in 168 subjects: 81 patients with clinically diagnosed e arly Alzheimer's disease (AD), 43 patients with other dementia, 11 Dow n's syndrome patients, and 33 nondemented neurologic control subjects. Multivariate ANOVA showed an effect of diagnostic group (p < 0.01) an d apolipoprotein E (apoE) allele (p < 0.005) on CSF tau. Comparison be tween diagnostic groups showed higher CSF tau levels in AD than in the control group (p < 0.001). However, CSF tau values in the non-AD deme ntia group did not differ significantly from those of AD patients or n eurologic control subjects. Tau levels were increased (p < 0.005) in A D patients with apolipoprotein E epsilon 4 allele, a well-characterize d risk factor of AD, compared with AD patients without epsilon 4 allel e, and the highest values were found in AD patients with two epsilon 4 alleles. These increased levels of CSF tau may indicate pronounced ne uronal degeneration and neurofibrillar pathology at the early stage of AD in patients carrying the epsilon 4 allele. This study shows that t he current ELISA test for CSF tau is not sensitive and specific enough to distinguish early AD from other dementias and indicates that in th e interpretation of CSF tau analysis as a diagnostic tool, the apoE ge notype should also be taken into account.