Total tau in cerebrospinal fluid differentiates Alzheimer's disease from vascular dementia

Tau protein is a microtubule-associated protein located in neuronal axons, which has been used in various configurations as a diagnostic marker of degenerative changes in the CNS. The aim of our study was to evaluate the use of CSF/ total tau in patients with Alzheimer-type dementia (AD) and vascular dementia (VD) compared to controls, in order to investigate.

A total of 102 persons were included in the study: 58 AD patients, 24 VD patients, and 20 non-demented controls. The Alzheimer group was divided into 3 subgroups by clinical stage of the disease. CSF samples were collected by routine lumbar puncture. The level of total tau protein was determined by sensitive sandwich enzyme-linked immunosorbent assay (ELISA).

CSF/total tau in the AD group was significantly higher than in the VD group (median 385.6 pg/ml vs. 101.2 pg/ml) and the controls (1.37 pg/ml). There were also significant differences among the AD stage groups in CSF total tau: highest in the group with severe dementia, intermediate in the group with moderate dementia, and lowest in the group with mild dementia. Differences in CSF total tau in all groups are not attributable to the patients' age.

CSF total tau clearly and simply differentiates AD from VD. CSF total tau in the incipient stage of AD and its increase in parallel with the progression of the disease may also provide a biochemical test to monitor the development of the disease.