Differences in Ventricle Dilation and Clinical Findings between the Early- and Late-Onset Subtypes of Alzheimer's Dementia

Abstract

The authors compared the characteristics of the early-onset subtype of Alzheimer's dementia (AD) with those of the late-onset subtype (SDAT) to determine whether Alzheimer's dementia (AD/SDAT) can be divided into two different diagnostic categories. In this study, AD refers to Alzheimer's in which the onset of disease occurred before 65 years of age; and SDAT refers to cases in which onset of illness occurred at age 65 or more. The studied parameters were distribution of age at disease onset, progression of speed of ventricular dilation, speed of deterioration of Hasegawa's rating scale for dementia (HRSD) score, and lesional pattern on the Japanese revised version of the GBS scale (GBSS-JR). The distribution of age at onset in 258 patients with AD/SDAT showed one peak. These patients included both outpatients and inpatients. A 30-month follow-up study to determine the degree of ventricular dilation was performed in 20 AD and 24 SDAT patients. For CT measurement, the width of the third and lateral ventricle (cella media index) was measured every 6 months after admission. Average ventricle width at admission was matched between the two groups. Twelve and 24 months after admission, the mean cella media index of patients with AD was significantly wider than that of patients with SDAT. In addition a deterioration speed of HRSD scores of 16 AD and 14 SDAT patients was compared every month for 5 months after admission. The average duration of illness and HRSD score at admission were matched in the two groups. Two and 3 months after admission, the average HRSD score of patients with SDAT was better (p<0.1) than that of patients with AD. GBSS JR scores 2 months after admission were compared between 16 AD and 14 SDAT patients. Only the average duration of illness of these patients was matched. In 24 of 38 items (63.2%), the scores of patients with AD were significantly worse than those of patients with SDAT. However, there were no items for which patients with SDAT had worse scores than those of patients with AD. These results indicate that the dilating speed of ventricles and the deterioration speed of cognitive function scores occur significantly faster in patients with AD as compared to those with SDAT. Thus, different clinical management of the two groups may required, regardless of the cause of disease.