• Alzheimer's disease;
  • apolipoprotein E ɛ4 allele;
  • cerebral blood flow velocity;
  • mild cognitive impairment;
  • transcranial Doppler ultrasonography

The aim of this study was to investigate the changes in cerebral blood flow velocity (CBFV) and its relation to apolipoprotein E (apoE) ɛ4 allele in mild cognitive impairment (MCI). Thirty MCI and 30 controls were assessed using Mini-Mental State Examination (MMSE) and Cambridge Cognitive Examination-Chinese version (CAMCOG-C), and then insonated in the anterior (ACA), middle (MCA) and basilar (BA) cerebral arteries using transcranial Doppler ultrasonography. Compared with controls, MCI showed significant decreases in the mean (Vm), systolic (Vs) and diastolic (Vd) CBFV, bilaterally in MCA and ACA (P < 0.05–0.001), but not in BA. Compared with 17 apoE ɛ4 allele non-carriers, 13 carriers in MCI showed significant CBFV decreases, bilaterally in MCA (P < 0.05–0.001). Our findings, the decreased CBFV in apoE ɛ4 allele carriers with MCI, suggest that a large sample and longitudinal study in CBFV and cognitive changes may have the implications on early diagnosis of Alzheimer's disease.