Background:It is not well known whether the distributions of variations of circle of Willis (CW) are different in different populations. Previous studies have indicated: (a) The variations of the structure of the CW in different populations and ethnic and (b) some correlation between those congenital anatomical variations and possible cerebrovascular diseases. The frequency of such anatomical variations has not been evaluated sufficiently in the Iranian population. The aim of this study is to find the variations of the anatomy of the vessels in the CW in sample population of Iranian people and compare it with other available studies in the literature, providing a new grouping for variations.Methods:Samples were obtained from 200 autopsies in different ages, all retrieved in the department of Forensic Medicine, Tehran university of Medical Sciences after achieving permission from the Department of Ethics and Medico-legal Sciences. The CW was examined directly, using magnification, at the base of the brain. The cerebral vessels were observed for their configuration and their calibers were measured directly. Variations were noted and grouped into different categories.Results:Out of the 200 specimens examined, 69 (34.5%) were compatible with the typical anatomy of the CW. In the remaining 65.5% of the specimens, there were variations in the CW. Hypoplasia of the posterior communicating arteries was the most common variation in our study. One of the autopsies showed the presence of an aneurysm (0.5%).Conclusion:The anatomical variations found in our study were not significantly different from those reported in the literature. Based on the available data; (a) there is no evidence that the distribution of the variations of the anatomy of the CW is different in various societies and (b) the prevalence of the congenital aneurysmal changes in this region is not low in the Iranian population.

Two decades of the amyloid-β (Aβ) hypothesis in Alzheimer's disease (AD) and the prominence of Aβ-targeting strategies have yet to meet the levels of original expectation. Disappointing results in numerous Phase II/III studies have called for a re-examination of the validity of the Aβ-targeting approaches as an intervention strategy in AD. The mid-life onset of chronic conditions (e.g., hypertension, diabetes, insulin intolerance, and depression nominated as risk factors for the later development of AD) points to the possibility that each condition could involve mechanisms, which while relatively modest over a short-term, could have significant accumulative effects. What may also not be fully appreciated is that a number of these conditions involve potential disturbances to multivalent cations (MC) levels through various mechanisms such as autophagy, oxidative stress, and apoptosis. Furthermore, some MCs have intimate associations with the mechanisms by which Aβ pathology manifests. Considering various lines of evidence and incorporating statistical analysis on Disability-Adjusted Life Years (DALYs) data of both causes of and prevalence of multifactorial risk factors in different world regions, we propose an MC hypothesis for AD. More specifically, we suggest that MC imbalance marks many chronic conditions and because of their involvement with Aβ pathology, could reflect that Aβ may be a vital manifestation and marker of underlying MC imbalance. Thus, careful targeting of MC imbalance may provide an alternative or complementary interventional approach to current Aβ treatment strategies.

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Different conditions including hemodynamic alteration, compression of adjacent hematoma, and narrowing of related vascular structures have been described to cause thrombosis of VoGAM. The relevant literature to address possible mechanism is reviewed.