Disorders of cerebrovascular angioarchitectonics and microcirculation in the etiology and pathogenesis of Alzheimer’s disease

Ivan V Maksimovich

doi:10.4236/aad.2013.24022

Abstract

There have recently appeared many reports dedicated to cerebral hemodynamics disorders in AD. However, certain specific aspects of cerebral blood flow and microcirculation during this disease are not fully understood. This research focuses on the identification of particular features of cerebral angioarchitectonics and microcirculation at preclinical and clinical AD stages and on the determination of their importance in AD etiology and pathogenesis. 164 patients participated in the research: Test Group—81 patients with different AD stages; Control Group— 83 patients with etiologically different neurodegenerative brain lesions with manifestations of dementia and cognitive impairment but without AD. All patients underwent: assessment of cognitive function (MMSE), severity of dementia (CDR) and AD stages (TDR), laboratory examination, computed tomography (CT), magnetic resonance imaging (MRI), brain scintigraphy (SG), rheoencephalography (REG) and cerebral multigated angiography (MUGA). All Test Group patients, irrespective of their AD stage, had abnormalities of the cerebral microcirculation manifested in dyscirculatory angiopathy of Alzheimer’s type (DAAT), namely: reduction of the capillary bed in the hippocampus and frontal-parietal regions; development of multiple arteriovenous shunts in the same regions; early venous dumping of arterial blood through these shunts with simultaneous filling of arteries and veins; development of abnormally enlarged lateral venous trunks that receive blood from the arterio-venous shunts; anomalous venous congestion at the border of frontal and parietal region; increased loop formation of distal intracranial arterial branches. Control group patients did not have combinations of such changes. These abnormalities are specific for AD and can affect amyloid beta metabolism contributing to its accumulation in the brain tissue and thereby stimulating AD progression.

Highlights

According to the Alzheimer’s Association in 2013, one of eight Americans older than 60 has memory impairments [1]
According to computed tomography (CT) and magnetic resonance imaging (MRI): ● Alzheimer’s disease (AD)-specific neurodegenerative changes in the brain manifested in temporal lobes atrophy which at different stages of the disease lead to 4% - 62% reduction in tissue mass were detected in 81 (100%) cases (Table 1); ● individual cerebral neurodegenerative changes were observed in a limited number of cases (Table 1)
By means of this method we were able to detect AD-specific disorders of blood circulation and microcirculation in the temporal and fronto-parietal brain regions among Test Group patients. We have named those disorders “dyscirculatory angiopathy of Alzheimer’s type” (DAAT) [32,50]. They do not occur among Control Group patients, and they are specific for AD and non-specific for other neurodegenerative diseases accompanied by the development of dementia and cognitive impairment

Summary

Introduction

According to the Alzheimer’s Association in 2013, one of eight Americans older than 60 has memory impairments [1]. AD has for long been considered a purely neurodegenerative disease, so the research has mainly focused on structural changes in the brain tissue during this disease [3,4,5]. The introduction of such radiological methods as CT, MRI and PET has made great progress in neuroimaging allowing to study in vivo the changes that occur in the brain tissue during various neurodegenerative processes as well as to differentiate various structural lesions [6,7,8,9]. The use of biomarkers in the diagnosis of AD has recently allowed visualizing the accumulation of amyloid-beta and tau [10,11,12,13]

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Conclusion