Hemorheological mechanisms in Alzheimer's disease.
OBJECTIVE
The aim of the present study was to elucidate the underlying mechanisms responsible for hemorheological abnormalities in elderly patients with Alzheimer's disease (AD).


METHODS
Twenty-one patients with AD and twenty-three age-matched healthy controls (CON) were studied. We used a controlled-shear rate rheometer generating various flow fields in vitro for simulating blood flow in vivo. The applied experimental techniques provided valid and quantitative data for the analysis of hemorheological abnormalities associated with AD. Principal blood biochemical parameters and hemorheological parameters, including blood viscosity, erythrocyte deformability, erythrocyte aggregation and oxygen transport efficiency of blood were assessed.


RESULTS
The results show no statistically significant difference in most of the blood biochemical parameters between the AD patients and the CON, except that fibrinogen concentration and mean corpuscular cell volume level of erythrocytes (MCV) were significantly higher in the AD patients. Hemorheological parameters including blood viscosity, plasma viscosity, and blood viscoelasticity in the AD patients were considerably higher than the respective factors in the CON. Owing to the MDA levels of the AD patients being significantly higher than that of the CON, the AD patients also showed a decrease in erythrocyte deformability and an increase in blood flow resistance despite the lack of any significant difference in erythrocyte rigidity. In addition, the erythrocyte aggregation of AD patients was higher than that of the CON and reduced oxygen transport efficiency of blood was observed in the AD patients.


CONCLUSIONS
The hemorheological abnormalities found in AD patients may be explained by the parallel findings of oxidative damage on erythrocyte membranes that could result in a decrease of erythrocyte deformability. Furthermore, the oxidative stress-induced elevation of fibrinogen concentration could lead to accelerated erythrocyte aggregation as a consequence of a rise in blood viscosity and blood viscoelasticity. Taken together, these factors may impair the oxygen transport efficiency of blood in AD patients.
Chang
Chia-Yu
CY
Department of Neurology, Chi Mei Foundation Hospital, Tainan, Taiwan.
Liang
Hong-Jen
HJ
Chow
Sin-Yu
SY
Chen
Szu-Ming
SM
Liu
Der-Zen
DZ
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000503:physiopathology*; D001692:Biological Transport; D001783:Blood Flow Velocity; D001809:Blood Viscosity; D016022:Case-Control Studies; D004903:Erythrocyte Aggregation; D004907:Erythrocyte Deformability; D018056:Hemorheology; D006801:Humans; D010100:Oxygen / Q000378:metabolism
D010100:Oxygen