The E.E.G. in presenile dementia.

There are numerous E.E.G. studies of patients with primary presenile dementia but general agreement on the findings is lacking, especially over (1) particular E.E.G. patterns in diagnostic subgroups and (2) the relationship between the degree of E.E.G. abnormality and the severity of dementia as manifested clinically. This lack of uniformity is due in part to the infrequency of an exact, that is, histological diagnosis. For example, the detailed E.E.G. study by Letemendia and Pampiglione (1958) was made on 17 patients with Alzheimer's disease but in only five was cerebral biopsy performed to confirm the diagnosis. Liddell's (1958) study of E.E.G. findings in 11 presenile dements provided a histological diagnosis in only three patients and that after necropsy. Green, Stevenson, Fonseca, and Wortis (1952), who performed cerebral biopsy in 19 patients with primary presenile dementia, reported the E.E.G. findings in only seven cases of Alzheimer's disease and found that they did not differ essentially from those obtained in eight patients with non-specific encephalopathy. As all but one of their patients with Alzheimer's disease were incontinent, this would suggest that the disease was well advanced (Sim, Turner, and Smith, 1966). As most E.E.G. studies reported concern presenile dements in relatively advanced stages of their particular disease, this has led to (1) blurring of the end-points of clinical diagnosis where there was no histological confirmation, and/or (2) confining the E.E.G. findings to only one stage of the disease, namely, the late stage. For example, Letemendia and Pampiglione (1958) state that most of their patients with Alzheimer's disease exhibited apathy, the average duration of illness being seven years, and that 'an artefact-free record was difficult to obtain as the patient's cooperation was often poor. In the frontal region the potential changes due to eye movement were often troublesome'. Again, Liddell (1958) commented that most of his patients were so demented that they were not capable of being tested psychologically.