Central autonomic nervous tract integrity of the brain is linked to blood pressure

Background: Hypertension is closely associated with autonomic dysfunction. The role of the structural integrity of the central autonomic network (CAN) of the brain is insufficiently explored. Large-scale imaging data were used to investigate the relationship between the microstructural properties of the CAN with blood pressure (BP) and hypertension. Methods: We analysed MRI data from 43 994 individuals to investigate whether BP levels were linked to the microstructural integrity of white matter tracts involved in autonomic control (CAN tracts). To test the specificity of these associations, we compared them to randomly selected white matter regions not specifically tied to the autonomic network, aiming to identify whether CAN tracts had a stronger connection to BP and which subsystems were particularly affected. Results: Our findings showed that BP was more strongly linked to the microstructural integrity of CAN tracts than to other white matter regions. Further analysis revealed that specific CAN subsystems had distinct associations with BP, with higher levels of free water in these regions being associated with increased BP and hypertension. Additionally, the severity of hypertension was associated with the level of microstructural integrity in CAN tracts. Conclusion: This study provides evidence of a specific relationship between BP levels and the microstructural integrity of the CAN. We found that, particularly in cortical parts of the CAN, higher levels of free water – indicating tissue not actively involved in neural signalling – were associated with elevated BP levels and a greater risk of hypertension. This evidence supports a close link between the central autonomic system and BP from a population-imaging perspective.