Cerebrospinal fluid tau protein is not a biological marker in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder leading to progressive motor neuron cell death. Etiopathogenesis is still imperfectly known and much effort have been undertaken to find a biological marker that could help in the early diagnosis and in the monitoring of disease progression. Cerebrospinal fluid (CSF) concentrations of tau, an axonal microtubule-associated protein, have been measured in ALS with levels found increased in some studies and unchanged in others. Methods: Total CSF tau level was assayed in a population of ALS patients (n= 57) and controls (n= 110) using a specific ELISA method. Results: No sig- nificant differences in the median CSF tau levels between ALS cases and controls were found [ALS: 126 pg/ml (78–222); controls: 112 pg/ml (71–188), P= ns]. In the ALS group, the bulbar-onset patients showed increased CSF tau levels as compared with the spinal-onset cases. These differences might be related to the higher age of the bulbar-onset patients. Further, no correlations were found between CSF tau con- centrations and the rate of progression of the disease. Conclusions: These results do not support the hypothesis that total CSF tau protein is a reliable biological marker for ALS