Association between heart rate variability and striatal dopamine depletion in Parkinson's disease

Striatal dopamine depletion is associated with not only motor symptom but also non-motor symptoms in patients with Parkinson's disease (PD). The purpose is to elucidate the relation between heart rate variability (HRV) and dopaminergic depletion in specific striatal subregions. The subjects were 84 patients with newly diagnosed untreated PD. All patients underwent striatal I-123-2 beta-carbomethoxy-3 beta-(4-iodophenyl)-N-(3-fluoropropyl) nortropane (I-123-FP-CIT) dopamine transporter single-photon emission computed tomography (DAT-SPECT). DaTQUANT software (GE Healthcare) was used as a semi-quantitative tool to analyze DAT-SPECT data. Association of HRV with dopaminergic depletion in specific striatal subregions was examined. HRV was related to dopamine depletion in the caudate and anterior putamen, especially the left side, after controlling for age, hemoglobin A1c level, disease duration, and motor severity on multiple regression analysis (left caudate; beta = 0.269, p = 0.030, left anterior putamen; beta = 0.315, p = 0.012). HRV was closely related to striatal dopamine depletion, especially in the left associative striatum, in patients with PD.