Low Density Rate Research Articles

CT study in senile dementia of Alzheimer type

AbstractWe evaluated 14 patients with senile dementia of Alzheimer type (SDAT) and 15 age‐matched normal elderly controls using psychological test and computed tomography scans. The low‐density rate (LDR) was used as an index of brain atrophy. SDAT patients had significantly higher scores on the Hasegawa Dementia Scale (p< 0.01) and significantly lower scores on the Bender Gestalt Test (p<0.01) than control subjects. The LDRs of the left and right hemispheres were significantly higher in the SDAT group than in the control group in all three slices investigated (p<0.05/6 = 0.0083). In SDAT patients, significant diagnosis by hemisphere interaction was observed in one slice (p<0.05), with higher LDR on the left than on the right (p<0.05/6 = 0.0083). Our findings suggest that cortical atrophy is predominant on the left side in patients with SDAT.

Brain Atrophy and Intellectual Impairment in Tardive Dyskinesia

Fourteen chronic schizophrenic patients with tardive dyskinesia (TD) and 13 without TD were given psychological tests and CT scans. The low density rate (LDR), i.e., the ratio of the X-ray absorption (corresponding nearly to that of cerebrospinal fluid) of a brain lesion to the X-ray absorption of the whole brain, was used as an index of brain atrophy (HN-method). The LDR of the left hemisphere of the TD patients was significantly higher than that of non-TD patients in the basal nucleus and lateral ventricle, and the LDR of the right hemisphere for the TD patients was significantly higher than that of non-TD patients in the basal nucleus. The Hasegawa Dementia Rating Scale (HDRS) and Bender-Gestalt Test (BGT) for the TD patients were significantly lower than those for the non-TD patients. Our study revealed that brain atrophy was greater in TD than in non-TD patients and tended to be more pronounced in the left hemisphere, and that the degree of intellectual impairment was greater in the TD patients than in the non-TD group. The results suggest that schizophrenic brains with TD tend to be more easily damaged than those without TD, that this tendency predominates on the left side, and that intellectual impairment in TD is related to brain atrophy.