ObjectiveCushing's syndrome (CS) is associated with neuropsychological deficits. As the cerebellum plays a key role in neuropsychological functions it may be affected in CS. The aim of this study was to investigate whether patients with CS have a smaller cerebellar volume than healthy controls, and to analyse whether cerebellar volume is associated with neuropsychological performance and clinical parameters.DesignA cross-sectional study was performed.MethodsThirty-six CS patients (15 with active CS and 21 with CS in remission) and 36 controls matched for age, sex, and education underwent neuropsychological testing, quality of life assessment, clinical evaluation, and magnetic resonance imaging brain scan. Cerebellar volumes (white matter and cortex, bilateral) were calculated using FreeSurfer Software.ResultsPatients with active CS showed smaller bilateral cerebellar cortex volumes than controls (left,P=0.035 and right,P=0.034), as well as a trend toward smaller right cerebellar cortex volumes than patients in remission CS (P=0.051). No differences were observed in the volume of cerebellar white matter between the three groups. Both right and left cerebellar cortex volumes correlated negatively with triglyceride levels (right:r=−0.358,P=0.002 and left:r=−0.317,P=0.005) and age at diagnosis (right:r=−0.433,P=0.008 and left:r=−0.457,P=0.005). Left cerebellar cortex volume also correlated positively with visual memory performance (r=0.245,P=0.038). Right cerebellar cortex volume positively correlated with quality-of-life scores (r=0.468,P=0.004).ConclusionsThe cerebellar cortex volume is smaller in active CS patients than in controls. This finding is associated with poor visual memory and quality of life and is mostly pronounced in patients with higher triglyceride levels and older age at diagnosis.