Reduced CSF carboxyterminally truncated Aβ peptides in frontotemporal lobe degenerations

Cerebrospinal fluid (CSF) carboxyterminally truncated amyloid-beta (A beta) peptides, A beta 1-42 and tau protein were evaluated in 30 patients with frontotemporal lobe degenerations (FTLD), 30 Alzheimer's disease (AD) patients and 30 non-demented disease controls (NDC) by A beta-SDS-PAGE/immunoblot as well as commercial ELISAs for A beta 1-42 and total tau. FTLD displayed a significant drop of A beta 1-37 (p = 2.7 x 10(-4)), A beta 1-38 (p = 4.2 x 10(-5)) and A beta 1-42 (p = 3.3 x 10(-4)). A beta 1-42 was selectively decreased in AD (p = 8.5 x 10(-1)). Decreased A beta 1-38 enabled contrasts of beyond 85% to distinguish FTLD from AD and NDC patients, alone or in combination. Accordingly, low CSF A beta 1-37 and A beta 1-38 represent a biomarker candidate for FTLD and may reflect disease-specific changes of APP metabolism. Further validation should be carried out on dementias other than AD, diagnostically relevant control groups without dementia and without any evident affection of the central nervous system and subgroups of FTLD. Moreover, independent methods of measurement should be applied to CSF A beta 1-38.