Diabetes may contribute to cognitive impairment in Parkinson's disease via damaging white matter tracts.

Parkinson's disease with dementia (PDD) severely affects the quality of life of patients with Parkinson's disease (PD) in the later stages. Recently, PD patients with diabetes were found to have a higher risk of cognitive decline and developing dementia with a faster progression, but the underlying mechanism remains unclear. Diabetes-related white matter damage may partially explain the mechanism by which diabetes participates in PDD. Seventy PD patients were included. PD patients underwent diffusion tensor imaging from The Second Affiliated Hospital of Chongqing Medical University were collected and were divided into four groups: PD with diabetes without dementia, PD with dementia without diabetes, PD without dementia and diabetes. Tract-based spatial statistics analysis and region-of-interest-based analysis were performed. Factorial analysis with diabetes and dementia taken as the main effects was performed, and the differences between the white matter fibers of PD patients from the four groups were also analyzed. The interaction between diabetes and dementia in the damage of white matter in PD patients was also analyzed. We found that both diabetes and dementia were found to be related to the damage in internal capsule, corona radiata, and thalamic radiation of the PD patients. There is an interaction between diabetes and dementia in the white matter damage of PD patients. Both diabetes and dementia were found to be related to the damage in internal capsule, corona radiata, and thalamic radiation of the PD patients. Diabetes may participate in cognitive decline in PD patients via damaging cognition-related white matter tracts.