<b><i>Background:</i></b> Coronavirus disease 2019 (COVID-19), the far-reaching pandemic, has infected approximately 185 million of the world’s population to date. After infection, certain groups, including older adults, men, and people of color, are more likely to have adverse medical outcomes. COVID-19 can affect multiple organ systems, even among asymptomatic/mild severity individuals, with progressively worse damage for those with higher severity infections. <b><i>Summary:</i></b> The COVID-19 virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), primarily attaches to cells through the angiotensin-converting enzyme 2 (ACE2) receptor, a universal receptor present in most major organ systems. As SARS-CoV-2 binds to the ACE2 receptor, its bioavailability becomes limited, thus disrupting homeostatic organ function and inducing an injury cascade. Organ damage can then arise from multiple sources including direct cellular infection, overactive detrimental systemic immune response, and ischemia/hypoxia through thromboembolisms or disruption of perfusion. In the brain, SARS-CoV-2 has neuroinvasive and neurotropic characteristics with acute and chronic neurovirulent potential. In the cardiovascular system, COVID-19 can induce myocardial and systemic vascular damage along with thrombosis. Other organ systems such as the lungs, kidney, and liver are all at risk for infection damage. <b><i>Key Messages:</i></b> Our hypothesis is that each injury consequence has the independent potential to contribute to long-term cognitive deficits with the possibility of progressing to or worsening pre-existing dementia. Already, reports from recovered COVID-19 patients indicate that cognitive alterations and long-term symptoms are prevalent. This critical review highlights the injury pathways possible through SARS-CoV-2 infection that have the potential to increase and contribute to cognitive impairment and dementia.

Objectives: Brain arterial dilation is an increasingly recognized cerebrovascular disease marker. However, demographic and anatomical factors may influence brain arterial diameters within the normal spectrum. We hypothesize that age, sex, height, total cranial volume (TCV) and fetal posterior cerebral arteries (fPCA) presence correlate with brain arterial diameters across diverse populations. Methods: We included participants with available time-of-flight MRA from 9 cohort studies across the United States (4), Ecuador (1), Venezuela (1), South Africa (1) and Singapore (2). Arterial diameters of the basilar artery (BA), cavernous internal carotid arteries (ICAs) and middle cerebral arteries (MCAs) were measured using LKEB Automated Vessel Analysis (LAVA) software. Linear regression models were fitted to assess the association between brain arterial diameters and exposures. The R-squared was calculated to assess the extent of brain arterial diameter variation explained by the variables studied. Results: The sample included 6,269 participants (mean age 68 years; 42% men). Unilateral fPCA was found in 12.6% and bilateral fPCAs in 3.0%. Older age, male sex and TCV were uniformly correlated with larger BA, ICA and MCA diameters (Table). Unilateral and bilateral fPCAs showed a negative correlation with BA diameter and a positive correlation with ICA diameters in a dose-dependent manner. Models fitted for age, sex, TCV, and fPCA presence explained on average 24, 16 and 12 % of the BA, ICAs and MCA diameter interindividual variation, respectively. Using height instead of TCV decreased the R-squared by 2% on average. Conclusions: In this pooled analysis of cohort studies, we found brain arterial diameters consistently correlate with age, sex, TCV and fPCA presence. These factors should be considered to define abnormal arterial diameter cut-offs across populations. If resources are limited or if bedside applicability is desired, height could be used instead of TCV.