Background: The use of dihydropyridine calcium channel blockers (DCCBs) was proposed to reduce the risk of Parkinson's disease (PD). This study aimed to evaluate the association between DCCB and its dose effect and the risk of PD in patients with newly diagnosed hypertension. Methods: This population-based retrospective cohort study enrolled 107,207 patients with newly diagnosed hypertension, between 2001 and 2013, from Taiwan's National Health Insurance Research Database. Patients who had PD before hypertension or were taking antipsychotics for more than 30 days in the 6 months prior to the end of the observation period were excluded. A Cox proportional hazard model was used to estimate the risk of PD in different groups. The dose-related effects of DCCB on the risk of PD were evaluated according to the cumulative defined daily dose (DDD). Results: We observed 832 (1.2%) PD cases in patients treated with DCCB as compared to 950 (2.4%) PD cases in those not treated with DCCB, during a median follow-up duration of 8.3 years and 6.2 years, respectively. The risk of PD in the DCCB-treated group (hazard ratio [HR] = 0.50) was significantly lower than that in the group without DCCB treatment. DCCB reduced the risk of PD in a dose-dependent manner, with HRs ranging from 0.61 to 0.37 for DDDs of 90–180 to >720. Conclusions: DCCB treatment was associated with a significantly reduced risk of PD in patients with newly diagnosed hypertension. Further clinical trials are needed to confirm the proposed neuroprotective effects of DCCB in PD.
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