IC-P1-001: Volume reduction in cerebral blood flow in patients with Alzheimer's disease: A sonographic study

Abstract

Alzheimer disease (AD) is characterised by progressive impairment of memory and cognitive function. PET and SPECT, in previous studies, demonstrated consistent reduction of cerebral blood flow (CBF) in AD. Recently, reports have described the use of sonographic techniques in estimating CBF by measuring flow volumes of the extracranial carotid and vertebral arteries in healthy adults. Ultrasound techniques are more diffused than other procedures, less expensive, and the absence of adverse effects allows repeated examinations without risk for the patients. 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 and the vertebral arteries 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 internal carotid and vertebral arteries of both sides. All subjects underwent 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 degree of cognitive impairment was also present. The significance of the present study is a statistically demonstration of cerebral blood flow deficits in Alzheimer's disease using a non-invasive method. The global cerebral blood flow reduction is particularly prominent, as expected, and even more so in the more severe affected patients. Cerebral blood reduction is independent from vascular risk factors and may be due to cerebral vasoconstriction and decreased cerebral demand. Furthermore, color duplex flowmetry of the cervical arteries offers us an additional tool for the investigation of brain circulation and highlights several important characteristics of CBF in AD. In contrast to other neuroimaging techniques, the procedure may be performed and repeated at anytime and since it is not invasive and not expensive, it may be used for monitoring CBF in AD as well as for research on pharmacological factors affecting CBF.