Thalamic Nuclei Volumes Across Psychiatric and Neurological Disorders: A Multi-Site Magnetic Resonance Imaging Study

The human thalamus is an integrative hub for multiple cortical and subcortical circuits involved in both sensory processing and higher cognitive functions. Group-level thalamic volume differences have been reported for multiple psychiatric and neurological disorders, but previous studies have relied on small samples, covered few disorders, or only investigated the whole thalamus without considering subdivisions. In this multi-site study, we compared thalamic nuclei volumes across several psychiatric and neurological disorders (N = 5 094) and healthy controls (N = 4 552). Using structural MRI scans, we segmented 25 bilateral thalamic nuclei, corresponding to six anatomical groups. We included patients covering 11 clinical conditions including mild cognitive impairment (MCI), dementia (DEM), major depressive disorder, schizophrenia spectrum disorder (SCZ), clinical high risk for schizophrenia, bipolar spectrum disorder, autism spectrum disorder, attention-deficit/hyperactivity disorder, Parkinson’s disease, and multiple sclerosis (MS). Linear models revealed that some regions of the thalamus were significantly smaller in several conditions, with largest effects observed for MCI, DEM, SCZ and MS. The thalamic nuclei groups most affected across conditions were the medial and lateral thalamic groups, while the ventral and intralaminar groups were relatively spared. This pattern of effects largely corresponds with the canonical functional subdivision of the thalamus into higher-order and sensory thalamus. Clinical conditions differed when looking at the level of individual nuclei. The results highlight a role for the higher-order thalamus in common brain disorders and a differential involvement at the level of individual nuclei, contributing towards a mechanistic understanding of pathophysiological alteration in the thalamus.