Circulating beta amyloid protein is elevated in patients with acute ischemic stroke

Recent clinical and experimental studies suggest that ischemic strokes may play an important role in the pathogenesis of Alzheimer's disease (AD). Beta amyloid (Aβ), a major component of senile plaque in AD, is known to be derived from ischemic brain or activated platelets. We prospectively enrolled 62 patients with acute ischemic stroke and 27 age-matched controls. The serum Aβ and P-selectin levels were determined using the Sandwich-ELISA. We divided ischemic strokes into subgroups according to the clinical syndrome, pathogenesis, and infarct size, and compared the Aβ level between each subgroup. The Aβ1-40 level was markedly elevated in ischemic stroke patients, as compared to controls (140.2 ± 54.0 vs 88.44 ± 34.96 pg/ml, p<0.001). Cardioembolic and larger artery atherosclerotic infarcts had higher Aβ1-40 level than small vessel disease (p = 0.001). Both infarct size and the initial NIHSS score had significantly positive correlations with the serum level of Aβ1-40 (r = 0.539, p<0.001 and r = 0.425, p = 0.001, respectively). However, the P-selectin level was not significantly correlated with serum Aβ1-40. Our data suggest that elevated circulating Aβ1-40 in ischemic stroke patients may be derived from brain as a consequence of ischemic insults.