Substance Uses and Prefrontal Cortex, Thalamus, and Cerebellar Volumes: An Integrative Investigation on Brain Shrinkage (DSI-SRP)
This DSI-SRP fellowship funded Qiaochu (Francis) Jiang to work in the laboratory of Neil Woodward in the Department of Psychiatry during the summer of 2021. Qiaochu is a senior with majors in Neuroscience and Psychology and a minor in Asian Studies.
Substance use disorder (SUD), or substance abuse, is characterized by excessive and continued use of a substance, such as alcohol, cannabis, and tobacco, despite potentially detrimental personal and health effects. Studies have shown that substance use disorder is related to a broad range of behavioral and cognitive deficits and is associated with decreased brain volumes. The main goal of this project was to investigate the effects of substance use on the volumes of the prefrontal-thalamo-cerebellar circuit. This brain circuit is heavily involved with the sensorimotor, cognitive, executive functions and motor coordination, many of which show impairments in substance use disorder. However, the effects of substance use on brain volumes have been mixed, with some studies showing decreased volumes and some showing no differences. In addition, while most studies examine the prefrontal, thalamus and cerebellum as homogenous structures, these regions are composed of multiple subregions which all have different connectivity and functions. This project examined the association between substance use and volumes of thalamic, prefrontal and cerebellar subregions in two ways. First, subjects with SUD, focusing on alcohol use disorder and cannabis use disorder, were compared with healthy people to investigate if there was a difference by group in the volumes of the three brain regions. Second, the relationship between the continuous variables (age at onset of regular use, typical pattern, and duration of use) and the volumes of the regions was investigated.
This study used data from a large, publicly available community sample, which includes both behavioral and neuroimaging data. We approached the magnetic resonance (MR) imaging data by segmenting brain into subregions using FreeSurfer and by voxel-based morphometry using CAT 12. FreeSurfer segments the prefrontal cortex and the thalamus into their subregions, then we used repeated measures ANOVA and linear regression to examine group differences and association with substance use variables. To enhance the accuracy and consistency of the results across methods, we used voxel-based morphometry to examine the spatial extent of differences between groups within these regions. Analyzing both behavioral and brain imaging data from such a large sample pool, we found that compared to the healthy controls, subjects with alcohol use disorder had smaller right pulvinar nucleus volumes and while there was no significant difference in the prefrontal cortex between healthy control and subjects with alcohol use disorder. Currently, we have started investigating the different cerebellar lobules using SUIT, another toolbox for segmentation, normalization, and voxel-based morphometry analysis of the cerebellum, and examining the association between volumes and continuous substance use variables.
In addition to receiving support through a DSI-SRP fellowship, this project was supported and facilitated by the DSI Data Science Team through their regular summer workshops and demo sessions.