Year: 2012
Type: article
Abstract: Cardiovascular risk factors appear to influence the development of Alzheimer's disease (AD). However, the underlying mechanisms by which cerebrovascular dysfunction in particular contributes to AD is unknown. We tested the hypothesis that static cerebral autoregulation (sCA) is compromised in patients with amnestic mild cognitive impairment (MCI), a transitional state between normal cognitive aging and AD. 26 MCI patients (12 males, 67 ± 6 yr) and 18 age-and education-matched normal control subjects (6 males, 68 ± 7 yr) underwent cerebral autoregulation study. Mean Arterial blood pressure (MAP) was decreased stepwise by intravenous infusion of sodium nitroprusside (SNP) and then increased by phenylephrine. Transcranial and color duplex Doppler were used to measure cerebral blood flow (CBF) velocity of the middle cerebral artery (MCA, V MCA) and volumetric blood flow of the internal carotid (ICA, F ICA) and vertebral arteries (VA, F VA) in response to changes in MAP. End-tidal CO 2 (ETCO 2) was recorded simultaneously. Stepwise multiple linear regression analysis was used to examine the effects of ∆MAP, ∆ET CO 2, group (0 for control, 1 for MCI), age and gender (0 for female, 1 for male) on ∆V MCA, ∆F ICA, and ∆F VA (∆, percentage changes to baseline). The range of variations in MAP induced by drug infusion was 65∼143 mm Hg associated with a concomitant change in ETCO2 (range: 22∼48 mm Hg). The regression equations derived were: ∆VMCA = 0.170*∆MAP + 0.530*∆ ETCO2 + 0.189*Group + 0.252*Age, R = 0.719, P < 0.001; ∆FICA = 0.212*∆ ETCO2, R = 0.237, P < 0.01; ∆FVA = 0.221*∆MAP + 0.262*∆ ETCO2 + 0.256*Group, R = 0.475, P < 0.001. Significantly different CBF responses to ∆MAP and ∆ETCO2 between the MCI and control groups were observed in the MCA and VA, but not in the ICA. No gender differences were observed. Cerebral autoregulatory dysfunction was detected in patients with MCI, most prominently in the MCA and posterior cerebral territory (supplied mainly by the VA). These findings suggest that cerebrovascular dysfunction is detectable at the early stage of AD. A cause-effect relationship has yet to be established.
Source: Alzheimer s & Dementia
Language: English
Subfield: Psychiatry and Mental health
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W2086907226