Abnormal Development of Cerebellar-Striatal Circuitry in Huntington’s Disease: Supplemental Figures

Objective: To test the hypothesis that the trajectory of functional connections over time of the striatum and the cerebellum differs between pre-symptomatic patients with the HD gene expansion (GE) and patients with a family history of HD but without the gene-expansion (GNE), we evaluated function MRI data from the Kids-HD study. 

Methods: We utilized resting-state, functional MRI data from participants in the Kids-HD study between 6 to 18 years old.  Participants were divided into the GE (CAG 36-59) and GNE (CAG <36) groups.  Seed to seed correlations were calculated between four regions that provide input signals to the anterior cerebellum: 1) dorsocaudal putamen; 2) globus pallidus externa; 3) subthalamic nucleus, and 4) pontine nuclei and two regions that represented output from the cerebellum, the dentate nucleus to the: 1) ventrolateral thalamus and 2) dorsocaudal putamen. Linear mixed effects regression models evaluated differences in developmental trajectories of these connections over time between groups.

Results: Four of the six striatal-cerebellum correlations showed significantly different trajectories between groups.  All showed a pattern where in the early age ranges (6-12 years), there was hyperconnectivity in the GE compared to the GNE with those trajectories showing linear decline in the latter half of the age range.

Conclusion: These results parallel previous findings showing striatal hypertrophy in GE children as early as age 6.  These findings support the notion of developmentally higher connectivity between the striatum and cerebellum early in the life of the child with the HD gene expansion, possibly setting the stage for cerebellar compensatory mechanisms.