Volume Reduction in Cerebral Blood Flow in Patients with Alzheimer’s Disease: A Sonographic Study

Abstract

Neuroimaging techniques such as PET and SPECT demonstrated a consistent reduction of cerebral blood flow (CBF) in Alzheimer’s disease (AD). The aim of the study was to assess the potential role of ultrasonography for CBF measurement in AD patients and whether the CBF volume correlates positively with disease severity. Fifty patients who met the diagnostic criteria of probable AD (NINDS-ADRDA) were compared to 50 age-matched healthy elderly volunteers. The extracranial internal carotid arteries (ICAs) and the vertebral arteries (VAs) of the patients and controls were examined. Angle-corrected time-averaged flow velocity (TAV) and the diameter of the vessel were measured. Intravascular flow volumes were calculated as the product of TAV and the cross-sectional area of the circular vessel. CBF volume was calculated as the sum of flow volumes in the ICAs and VAs of both sides. All subjects underwent the MMSE. The mean global CBF (474.87 ± 94.085 vs. 744.26 ± 94.082 ml/min; p < 0.0001) was lower in AD patients than in healthy volunteers. A significant decline in global flow volumes (r = 0.48; p < 0.0007) with the degree of cognitive impairment was also present. The ability of ultrasonography to characterize flow decreases makes such a technique an attractive tool for the study of AD, for the evaluation of pharmacological therapies and, possibly, for early diagnosis.

Volume cerebral blood flow reduction in pre-clinical stage of Alzheimer disease:

“…The possible pathogenetic mechanism of brain hypoperfusion was discussed in our previous study [17]. In AD patients CBF reduction was neither influenced by vascular factors nor by cardiac fraction ejection, suggesting other mechanisms implicated in cerebral blood hypoperfusion.…”

“…The investigation was carried out by using a Siemens Elegra device with a 7.5-MHz linear-array probe. The examination technique has been described in details previously [17,[24][25][26][27][28] and it has been demonstrated to have a high intra (Spearman's rank correlation, r = 0.97) and inter (Spearman's rank correlation, r = 0.86) observer reproducibility [17]. Briefly, angle-corrected time-averaged flow velocity (TAV) and the diameter of the vessel were measured.…”

“…These methods have demonstrated great promise in the diagnosis and early detection of AD. Furthermore, correlation analysis between the cognitive status of the patients and the degree of cerebral hypoperfusion has provided evidence for the association of the two parameters [14][15][16][17]21].…”

“…■ Key words Alzheimer disease · cerebral blood flow · mild cognitive impairment · ultrasonography the extracranial cerebral arteries when compared to age-matched controls, suggesting that the measurement of CBF may represent a reliable and sensitive index of AD severity [17].…”

Effects of Blood Pressure Changes on Alzheimer’s Disease

“…MRI carried out in patients with probable Alzheimer's disease often shows a large number of white matter hyperintensities, which is a recognized marker of small vessel disruption [73,74] . Several studies using positron emission tomography, single photon emission computed tomography or transcranial Doppler have shown diminished cerebral perfusion in patients with Alzheimer's disease [75,76] . Concordant results come from epidemiological data that suggest cerebral ischemia/stroke could significantly increase not only the risk of vascular dementia, but also of Alzheimer's disease [18,77] .…”