[Neuropathologic investigation in autopsies with special emphasis on findings in Alzheimer's disease]

Abstract

Out of an average total of 1400 autopsies per year, neuropathological examinations were performed in 477 cases between 1997 and 1999 to investigate the incidence of dementias. The majority of the studied subjects were over 50 years old. Bielschowsky's and/or Gallyas's silver methods and, in some cases, protein tau (MAP) immunocytochemistry and amyloid staining were performed beside routine examination. Pathological changes were found in 212 of the 364 cases studied by the above methods but histological changes associated with dementia were only detected in 167 cases. The various forms of Alzheimer's dementia were also classified by age. The "incipient" form of Alzheimer's disease was verified in 23 cases. Old infarcts of various extensions were found in 42 percent of Alzheimer's dementias. Very mild or age-related degenerative changes were observed in 82 cases among subjects over 50 years old. Of these, eight patients died in their 90s. In some cases (n = 38) the number of neuritic plaques dominated over the number of neurofibrillary tangles but a reverse finding also occurred (n = 13). Neuronal degeneration was variable and was not always proportional to the number of neurofibrillary tangles. "Simple type of senile atrophy" was defined by the presence of minor or age-related Alzheimer changes and was considered a separate entity. The "incipient" form of Alzheimer's dementia was diagnosed in relatively young individuals where mild Alzheimer changes were found at the neuropathological examination. "Preclinical" Alzheimer's dementia could only be suspected by clinical data and could very rarely be supported by the neuropathological finding of "incipient" form. The ratio of pure Alzheimer's to vascular dementias cases proved to be 54:41 in this study. The results suggest that dementias are considerably underdiagnosed both in the clinical and pathological practice and that the recently defined "preclinical" and "incipient" forms are very hard to recognize both clinically and pathologically. The neuropathological study of the degenerative, mainly Alzheimer's type, findings in the randomly selected autopsies revealed great variations which raises many questions concerning the normal and pathologic aging of the brain as well as the "incipient" and senile forms of Alzheimer's dementia.