CLINICAL-FEATURES OF FRONTAL-LOBE DEMENTIA IN COMPARISON TO ALZHEIMERS-DISEASE

Over the past decade it has become evident that a substantial minority of patients with primary dementing diseases, particularly those prese nting in the presenium, have dementia of frontal lobe type (DFT) due t o non-Alzheimer's pathology. Although post-mortem remains the only met hod of definitive diagnosis, DFT and Alzheimer's disease (AD) can, we would claim, be separated with a high degree of certainty based on a c ombination of informant history, neuropsychology and neuroimaging. In DFT, changes in personality, motivation, social interaction and organi sational abilities, in the presence of well preserved memory and visuo spatial abilities, are characteristic. The lack of insight emphasises the need for independent information particularly as patients may perf orm normally on bedside (and more sophisticated) tests of cognition. P sychiatric features especially mood disturbance appear to be common, b ut their prevalence remains to be established. In contrast, AD is a pr ogressive amnestic disorder with episodic and semantic memory deficits , followed by breakdown in other attentional, perceptual and visuo-spa tial abilities, which reflects the major locus of pathology in AD, nam ely the medial temporal lobe. These features are illustrated by refere nce to a longitudinal study of 52 patients with minimal to moderate AD . In addition, we shall describe the results of retrospective and pros pective neuropsychiatric studies of a group of DFT patients.