Tau haplotype influences cerebral perfusion pattern in frontotemporal lobar degeneration and related disorders

Objective - The modulating factors on phenotypic expression of frontotemporal lobar degeneration (FTLD) remain still unknown. The aim of this study was to determine whether tau genetic variability modulates the brain functional and the clinical phenotypic expression of FTLD. Materials and methods - Clinical and neurological evaluations, a standardized neuropsychological assessments as well as a brain single photon emission tomography perfusion imaging studies were performed in 48 FTLD patients. Cerebral perfusion patterns were analysed according to H1 or H2 tau haplotypes by statistical parametric mapping and principal component analysis. Results - Two different patterns of cerebral dysfunction characterized the haplotypes, as hypoperfusion of frontal medial and cingulated cortex in H2-carriers and a prevalent involvement of posterior parietal regions in H1-carriers. Further, a significant increase of cerebrospinal fluid total tau and phospho tau levels was found in H2-carriers. Conclusions - These findings support a role of tau haplotype in modulating disease phenotype by influencing the hypoperfusion pattern and cerebrospinal fluid tau levels in FTLD.