Objective We aimed to investigate the relationship between tortuosity of the extracranial internal carotid artery (ICA) or vertebral artery (VA) and vascular risk factors among residents of Asahikawa, northeast Japan.

Methods We retrospectively surveyed participants of "brain dock" medical brain checkups, which involved magnetic resonance imaging and angiography. We measured the tortuosity of the ICA and VA, and evaluated vascular risk factors based on medical interviews, questionnaires, and medical records.

Results A total of 218 participants were enrolled in the study. ICA tortuosity (right and left) was significantly correlated with age [odds ratio (OR): 2.452, 95% confidence interval (CI): 1.695-3.548, p<0.001]. A more pronounced correlation was observed in females than in males (OR: 1.678, 95% CI: 1.004-2.807, p=0.048). VA tortuosity (right and left) was significantly correlated with age (OR: 1.786, 95% CI: 1.250-2.550, p=0.001) and smoking history (OR: 2.140, 95% CI: 1.235-3.707, p=0.007), and was more pronounced in females than in males (OR: 1.864, 95% CI: 1.107-3.137, p=0.019).

Conclusion ICA tortuosity was correlated with age, while VA tortuosity was correlated with age and smoking history. ICA and VA tortuosity were more pronounced in females than in males.