Background <p>Age is defined as the patient’s chronological age (in years) at hospital admission. The association between age and angiographic vasospasm remains controversial. This study aimed to explore the association between age and angiographic vasospasm in mechanically ventilated patients with aneurysmal subarachnoid hemorrhage (aSAH).</p> Methods <p>A secondary analysis was performed based on a retrospective study conducted from 2010 to 2015 in the intensive care unit (ICU) of a French university hospital.&#xa0;Factors associated with angiographic vasospasm were identified using univariate and multivariate logistic regression analyses. The non-linear relationship between age and angiographic vasospasm was assessed using restricted cubic spline regression, and the threshold effect was evaluated using a two-piecewise linear regression model.</p> Results <p>The study included 231 mechanically ventilated patients with aSAH. Their median age was 56&#xa0;years (range, 19–84&#xa0;years). Patients were divided into two groups based on the median age of 56&#xa0;years: younger (&lt; 56&#xa0;years) and older (≥ 56&#xa0;years). The rate of angiographic vasospasm was 34.63% (<i>N</i> = 80). After adjusting for potential confounders, patients in the older group were less likely to develop angiographic vasospasm [odds ratio (OR), 0.40; 95% confidence interval (CI), 0.19–0.85; <i>p</i> = 0.017] compared with those in the younger group. After adjusting for confounders, when age was ≤ 53&#xa0;years, the risk of angiographic vasospasm increased by 13% for each year increase in age (OR, 1.13; 95% CI, 1.05–1.22; <i>p</i> = 0.002). For age &gt; 53&#xa0;years, the risk of angiographic vasospasm decreased by 17% for each year increase in age (OR, 0.83; 95% CI, 0.77–0.89; <i>p</i> &lt; 0.001).</p> Conclusion <p>Age was non-linearly associated with the risk of angiographic vasospasm in mechanically ventilated patients with aSAH.</p>