Abstract W P151: Aging is Associated With Progressive Insufficiency of Circle of Willis Collaterals in Humans

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Introduction: Increasing age is the single largest non-modifiable risk factor for ischemic stroke. Recent studies have shown that increasing age is associated with inadequacy of leptomeningeal collaterals, and aging has been shown to cause a progressive decline in the number and diameter of collateral vessels in experimental mice, resulting in an increased collateral resistance and an enhanced stroke severity. Hypothesis: Aging leads to progressive loss of Circle of Willis collateral vessels in humans. Method: We studied a retrospective, consecutive series of 167 women and 112 men undergoing cerebral angiography for any reason. A blinded investigator scored the Circle of Willis collaterals for each angiogram using a scoring system of 0 - 2 for each collateral (0 = absent, 1 = hypo-plastic, 2 = robust) for a total score of 0 - 14. Collaterals scored included the bilateral A1 segments of the anterior cerebral arteries, bilateral P1 segments of the posterior cerebral arteries, bilateral posterior communicating arteries, and the anterior communicating artery. We compared the number of collaterals based on age, gender, and race as well as history of prior infarct, aneurysm, smoking, hypertension, diabetes, and obesity. Results: Females had significantly more collaterals than men (p = 0.04) . The average collateral score for males and females was 10.77 and 11.14, respectively. Patients younger than 60 years of age had a significantly higher number of collaterals (average collateral score, 11.54) compared with patients older than 60 (average collateral score, 10.47; p = 1.59 x 10 -9 ). Females exhibited a greater loss of collaterals with advancing age (p = 3.53 x 10 -5 ) than men (p = 0.00016). Data was subjected to the Dunn-Bonferroni corrected t-test for preplanned comparisons or the Student t-test. Conclusion: Based on our study, patients younger than 60 years are significantly more likely to have an angiographically-complete Circle of Willis. The underlying mechanism for this effect in humans is uncertain and the subject of a future study.