[A study on the difference between clinical and neuropathological diagnoses of age-related dementing illnesses; correlations with Hachinski's ischemic score].

In this study, clinical diagnosis and results of neuropathological examination were analyzed on 55 demented patients serially autopsied in a geriatric hospital. Based on clinical observations including Hachinski's ischemic score and CT scan, 30 cases were diagnosed as vascular dementia (VD), 16 cases as Alzheimer-type dementia (ATD), 6 as mixed-type dementia (MD), and 5 as other types of dementias. On the results of neuropathological examination, 25 cases were diagnosed as ATD, 19 cases as VD, 5 as diffuse Lewy body disease (DLBD), 4 as MD, and 2 as other types of dementias. The accuracy of the clinical diagnosis for ATD was 78.6%, and that for VD was 53.3%. Thus, misdiagnosis was more frequent on VD. Clinically, VD cases were rarely misdiagnosed as ATD, while ATD or MD cases were more frequently misdiagnosed as VD. Therefore, it is suggested that VD is overdiagnosed. One of the reasons is that risk factors of cerebrovascular disorders increase and Hachinski's ischemic score also becomes higher with the age of the patients. ATD is clinically diagnosed only after excluding other dementing illnesses. More detailed analysis of clinical features including cognitive function and brain images is required for more accurate clinical diagnosis of age-related dementing illnesses. Also in our series, DLBD was the second most frequent degenerative dementia following ATD, although all DLBD cases were clinically misdiagnosed as ATD or VD.