Morphologic variation of the circle of Willis is associated with cognitive impairment in a general population: The J-SHIPP study

BACKGROUND: An incomplete circle of Willis (CoW) is associated with ischemic stroke severity and patient prognosis. However, the clinical significance of an incomplete CoW in healthy adults remains unclear. We examined the association between incomplete CoW and cognitive decline in community-dwelling, apparently healthy, older adults. METHODS: A cross sectional study in 829 community-dwelling, functionally independent ≥50 years older adults (mean age: 67.4 ± 8.2 years) who voluntarily participated in the health checkup program provided by the Anti-Aging Center of Ehime University Hospital. Variations in CoW and the degree of cerebral small vessel diseases by Fazekas grading scale were assessed using magnetic resonance imaging. Cognitive function was assessed using a computer-based questionnaire. RESULTS: A total of 317 participants had complete CoW. Cognitive impairment was frequently observed in participants with absent CoW vessels (complete CoW: 5.7 %, absent 1 vessel: 9.0 %, absent ≥2 vessels: 12.2 %; P = 0.023). Grade 2 or higher white matter lesions in subcortical and periventricular regions were frequent in participants without multiple vessels. However, the association between incomplete CoW and cognitive impairment was independent of white matter lesions and conventional risk factors (absent 1 vessel: odds ratio = 1.76, P = 0.09; absent ≥2 vessels: odds ratio = 2.21, P = 0.014). CONCLUSION: The absence of 2 or more vessels was independently associated with cognitive impairment in a general population, which suggests that CoW variation is a risk factor for cognitive decline. FUNDING: This work was supported by a Grant-in-Aid for Scientific Research (20390185, 21H04850, 25293141) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.