Explicit memory in frontotemporal dementia: the role of medial temporal atrophy

In our memory clinic experience, memory impairment differs widely in patients with frontotemporal dementia (FTD). We searched for a correlation between explicit memory disturbance assessed with the Grober and Buschke test and medial temporal atrophy on CT scan in 22 consecutive patients with FTD. Five of the 22 patients had a medial temporal lobe (MTL) atrophy. There was no significant difference between the two groups for the demographic characteristics. Free recall, cued recall and the learning curve were significantly better in patients without MTL atrophy. The patients with MTL atrophy made more intrusions. We found a positive correlation between total recall and cued recall and the mean of medial temporal lobe measurement. These results are in agreement with the role of the hippocampal formation in the memory process. In our group, the ratio of patients with MTL atrophy is similar to the ratio of Pick's disease in frontotemporal dementia. In histological series more severe hippocampal atrophy are reported in Pick's disease. Therefore MTL atrophy on CT scan could be a marker of Pick's disease in FTD.