Cytoskeleton proteins in CSF distinguish frontotemporal dementia from AD

Objective and Background: To investigate the CSF levels of tau and the ligh t neurofilament protein (NFL) in patients with frontotemporal dementia (FTD ) and other common dementia disorders as well as normal control subjects. B oth proteins have been implicated in the pathophysiology of FTD. Methods: C SF levels of tau and NFL were investigated in 18 patients with FTD, 21 pati ents with early-onset AD (EAD), 21 patients with late-onset AD (LAD), and 1 8 age-matched control subjects. Results: Mean +/- SD CSF NFL levels were in creased in patients with FTD (1442 +/- 1183 pg/mL; p < 0.05) and LAD (1006 +/- 727 pg/mL; p < 0.001) compared with control subjects (241 +/- 166 pg/mL ) and in LAD compared with EAD (498 +/- 236 pg/mL; p < 0.05), and tended to be increased in FTD compared with EAD. CSF tau levels were increased in EA D (751 +/- 394 pg/mL; p < 0.01) and LAD (699 +/- 319 pg/mL; p < 0.01) compa red with control subjects (375 +/- 170 pg/mL), and in EAD (p < 0.001) and L AD (p < 0.01) compared with FTD (354 +/- 140 pg/mL). CSF NFL correlated pos itively with degree of cognitive impairment in FTD (r = 0.59; p < 0.05) and LAD (r = 0.61; p < 0.01). No significant differences were found in CSF NFL or CSF tau when comparing patients who did and did not possess the APOE-ep silon 4 allele within each diagnostic group. Conclusion: The results sugges t a differential involvement of these cytoskeleton proteins in FTD and EAD, with NFL primarily involved in the pathophysiology of FTD and tau in that of EAD. The increase in CSF NFL found in LAD might reflect the white-matter degeneration found in a proportion of LAD cases.