TH and Parkinson disease: Earlier research demonstrated that PD patients present with a reduction in the tyrosine hydroxylase (TH)‐positive sympathetic neurons in the heart (Amino et al., 2005; Takahashi et al., 2015), and recent findings have established PD‐associated pathology, such as Lewy bodies (LBs), in the heart (Javanshiri et al., 2022).