Hippocampal atrophy on MRI in frontotemporal lobar degeneration

Background: Hippocampal atrophy on MRI is an early characteristic of Alzheimer’s disease (AD). However, hippocampal atrophy may also occur in other dementias, like frontotemporal lobar degeneration (FTLD). Aim: To investigate hippocampal atrophy on MRI in FTLD and its three clinical subtypes, in comparison to AD, using volumetry and a visual rating scale. Methods: Forty-two patients with FTLD (17 frontotemporal dementia, 13 semantic dementia and 12 progressive non-fluent aphasia), 103 patients with AD and 73 controls were included. Hippocampal volumetry and the easily applicable medial temporal lobe atrophy (MTA) rating scale were applied to assess hippocampal atrophy. Results: Multivariate analysis of variance (MANOVA) for repeated measures showed a significant effect of diagnostic group on hippocampal volume. There was a significant diagnosis by side (left versus right) interaction. Both FTLD and AD showed hippocampal atrophy compared to controls. Results of the visual MTA rating scale confirmed these findings. Within the FTLD subtypes marked differences in hippocampal atrophy existed. Frontotemporal dementia and semantic dementia showed bilateral hippocampal atrophy and in semantic dementia the left hippocampus was smaller than in AD. Finally, in nonfluent progressive aphasia no significant hippocampal atrophy was detected. Conclusion: We provide evidence that hippocampal atrophy is not only a characteristic of AD, but also occurs in FTLD. The three clinical subtypes of FTLD show different patterns of hippocampal atrophy. group.bmj.com on November 7, 2016 Published by http://jnnp.bmj.com/ Downloaded from