Fronto-temporal dementia versus Alzheimer disease

Neuropsychology can be useful for differentiating patients with fronto-temporal dementia (FTD) from those with Alzheimer disease (AD). In contrast with the extensive literature on AD, relatively less is known about the cognitive impairment of FTD. It may have two presentations: (i) a progressive change in personality and in executive functions, and (ii) a progressive fluent aphasia with severe semantic disruption. We compared 4 patients with FTD and amyotrophic lateral sclerosis (ALS), with a 1-year history of progressive change in personality, loss of insight disinhibition and perseveration, to a group of 4 probable-AD patients according to the NINCDS-ADRDA criteria, with progressive cognitive impairment since at least one year. None of the participants had any symptomatic therapies. All the results were compared to those of a control group of 4 healthy volunteers. All the three groups underwent a complete battery of tests twice, with six months interval. During the first session, we detected a significant difference in the AD group if compared to the FTD group in sustained concentration, in short-term memory and in similarity tasks. On the contrary, there was a significantly worse performance in proverb interpretation task in the FTD group. After six months, AD patients got worse in all tasks if compared to the FTD performances, apart from the proverb interpretation item, in which the latter group was worse. These results demonstrate that early FTD and AD can be differentiated, with particular regard to the attentive, abstractive and reasoning subtests, in which the FTD group shows poorer results. Memory, calculation and language were relatively well spared in FTD population at the beginning, and got progressively worse, during the following six months. On the other hand, the cognitive decline of AD in this period seems to be deeper, faster and more destroying for the patients.