Differences in erythrocyte aggregability between multi-infarct dementia and Alzheimer's disease.

We reported previously that erythrocyte aggregability (RBC-A) is enhanced in patients with cerebral infarction. The purpose of the present study was to examine whether or not differences in RBC-A exist between multi-infarct dementia (MID) and Alzheimer's disease. The subjects comprised 16 patients with MID (7 males and 9 females, 73 ± 11 years old) who had Hachinski's ischemic scores of 7 or more and displayed multiple infarctions on brain computed tomography and 18 patients with Alzheimer's disease (8 males and 10 females, 70 ± 8 years old) who were diagnosed using the criteria proposed by the NINCDS-ADRDA Work Group. The patients underwent tests for cognitive function employing Hasegawa's dementia scale. RBC-A was measured using the whole-blood RBC aggregometer developed by us with concomitant measurement of blood factors such as the hematocrit, albumin/globulin ratio (A/G ratio) and fibrinogen. The RBC-A value in MID (0.170 ± 0.030/s) was significantly higher (p < 0.01) than that in Alzheimer's disease (0.135 ± 0.022/s). The hematocrit and concentration of fibrinogen did not reveal any differences between MID and Alzheimer's disease. However, the A/G ratio in MID (1.59 ± 0.43) was significantly lower (p < 0.01) than in Alzheimer's disease (2.01 ± 0.35). The above results suggest a potential usefulness for erythrocyte aggregability in differentiating between the two types of dementia.