This study was undertaken to investigate L‐type calcium channel blockers of the dihydropyridine class for association with Parkinson disease (PD), because some of these drugs traverse the blood–brain barrier, are potentially neuroprotective, and have previously been evaluated for impact on PD risk.

We identified 1,931 patients with a first‐time diagnosis for PD between 2001 and 2006 as reported in the Danish national hospital/outpatient database and density matched them by birth year and sex to 9,651 controls from the population register. The index date for cases and their corresponding controls was advanced to the date of first recorded prescription for anti‐Parkinson drugs, if prior to first PD diagnosis in the hospital records. Prescriptions were determined from the national pharmacy database. In our primary analyses, we excluded all calcium channel blocker prescriptions 2 years before index date/PD diagnosis.

Employing logistic regression analysis adjusting for age, sex, diagnosis of chronic pulmonary obstructive disorder, and Charlson comorbidity score, we found that subjects prescribed dihydropyridines (excludes amlodipine) between 1995 and 2 years prior to the index date were less likely to develop PD (odds ratio, 0.73; 95% confidence interval, 0.54–0.97); this 27% risk reduction did not differ with length or intensity of use. Risk estimates were close to null for the peripherally acting drug amlodipine and for other antihypertensive medications.

Our data suggest a potential neuroprotective role for centrally acting L‐type calcium channel blockers of the dihydropyridine class in PD that should be further investigated in studies that can distinguish between types of L‐type channel blockers. ANN NEUROL 2010;67:600–606