White Matter Microstructural Properties of the Superior Cerebellar Peduncles Predict Change in Internalizing Symptoms in Adolescent Girls

Internalizing symptoms typically emerge in adolescence and are more prevalent in females than in males; in contrast, externalizing symptoms typically emerge in childhood and are more commonly observed in males. Previous research has implicated aspects of white matter organization, including fractional anisotropy (FA), of cerebral tracts in both internalizing and externalizing symptoms. Although the cerebellum has been posited to integrate limbic and cortical regions, its role in psychopathology is not well understood. In this longitudinal study, we investigated whether FA of the superior (SCP), middle, and inferior cerebellar peduncles predict change in symptoms and whether sex moderates this association. 111 adolescents completed the Youth Self-Report, assessing symptoms at baseline (ages 9-13 years) and again two years later. Participants also underwent diffusion-weighted imaging at baseline. We used deterministic tractography to segment and compute mean FA of the cerebellar peduncles. Lower FA of the right SCP at baseline predicted increases in internalizing symptoms in females only (t(103)=−0.47, p=.020). Lower FA in the right SCP and inferior cerebellar peduncle also predicted increases in externalizing symptoms, but these associations did not survive multiple comparisons correction. There was no association between FA of the cerebellar peduncles and change in symptoms in males, or between middle cerebellar peduncle FA and symptom changes in males or females. Organizational properties of the SCP may be a sex-specific marker of internalizing symptom changes in adolescence. The cerebellar peduncles should be explored further in future studies to elucidate sex differences in internalizing and externalizing symptoms.