Differential impact of cerebral small vessel disease on thalamic regulation of anxiety: insights from 7T MRI

Little is known about how thalamic vascular patterns interact with small vessel diseases (SVDs) to influence affective symptoms. Here we collected 7-Telsa magnetic resonance imaging (MRI) data from 84 individuals with SVD and analyzed the influences of thalamic vascular pattern on affective symptoms, aiming to elucidate the underlying mechanisms driven by brain structure and function in the context of SVD. Subjects with a combined arterial supply by tuberothalamic and paramedian arteries to the right thalamus exhibited a lower Hamilton Anxiety scale (HAMA) score. When grouped by SVD burden, the same correlation remained in subjects with low SVD burden, whereas no difference was observed in the high SVD burden group. Interestingly, interaction effects of SVD and thalamic vascular pattern were also found affecting thalamic volume and resting-state brain activity in ventromedial prefrontal cortex (vmPFC). With moderated mediation analysis, right thalamic vascular pattern was indicated to affect anxiety through both direct (vascular pattern → HAMA score) and indirect (vascular pattern → thalamic volume → HAMA score) pathways. But high SVD burden interrupted the effects of right thalamic vascular pattern on HAMA score and thalamic volume. The finding that subjects with a combined arterial supply to the right thalamus exhibited a lower level of anxiety may suggest a novel vascular resilience for regulating anxiety. However, this vascular compensation mechanism was found to be impaired by elevated SVD burden and the disrupted inhibitory vmPFC activity caused by impaired thalamus. The findings of the present study provide a new underlying mechanism for affective disorders with SVD involved.