Frontotemporal Dementia

The predominantly behavioral changes of the frontal lobe syndrome often begin under sixty-five years of age with apathy and disinterest, which may be mistaken for depression. On the other hand, the symptoms of disinhibition may suggest a manic psychosis. They may occur paradoxically at the same time. The behavioral manifestations, therefore, are more likely to be presented to a psychiatrist than to a neurologist. Some of the more florid manifestations of disinhibition such as hyperorality (in which patients overeat, or put objects in their mouths) and hypersexuality are interpreted as being due to involvement of both temporal lobes, a phenomenon known as Kluver-Bucy syndrome. Progressive decrease of language output frequently appears later but can be seen at the same time as the behavioral problems. Neuroimaging studies such as CT, MRI, and SPECT scans are important for diagnostic confirmation. Behavioral quantitation may be more useful than cognitive testing. Kertesz and others (1997) constructed a twenty-four-item Frontal Behavioral Inventory (FBI), to ask the caregiver about the most specific behaviors. The FBI is used at the initial interview or for retrospective diagnosis.

At times FTD is associated with motor neuron diseases (MND) such as amyotrophic lateral sclerosis. Recently it was shown that some cases of FTD with or without MND have specific ubiquitin positive, tau negative cytoplasmic inclusions similar to that found in MND.