Can Drug Therapy Prevent Parkinson’s Disease?

A recent issue of the journal Neurology published two separate case-controlled studies that showed a decreased risk for Parkinson’s disease associated with both cholesterol-lowering medication and blood pressure-lowering medication.

A common class of cholesterol-lowering medications, HMG-CoA reductase inhibitors (also collectively called “statins”), includes the well-known and often-prescribed atorvastatin (Lipitor), simvastatin (Zocor), lovastatin (Altocor, Mevacor), and pravastatin (Pravachol). In the current study, each of these drugs, except pravastatin, was associated with a 60 to 70% decreased risk of Parkinson’s disease. Most of the benefit of these drugs was seen with long-term use greater than five years. No risk reduction was associated with the use of pravastatin. This study included approximately 650 subjects from three rural California counties.

The statins may reduce the risk of Parkinson’s disease through mitigating neuronal damage with antioxidant activity and anti-inflammatory effects, and by improving cerebral blood flow. These neuroprotective effects are controversial, however, and several studies have been published recently that do not report any benefit in Parkinson’s disease. Further, there is some data that suggests that high cholesterol itself is a risk factor for Parkinson’s disease. On the other hand, some studies have reported that high cholesterol may actually be protective and associated with a decreased risk of Parkinson’s disease.

The second study to appear in Neurology examined the link between blood pressure medications (antihypertensives) and Parkinson’s disease. The study examined multiple classes of antihypertensives, but found only calcium channel blockers were associated with a decreased risk of Parkinson’s disease. No risk reduction was seen with angiotensin converting enzyme (ACE) inhibitors, beta-blockers, or angiotensin II receptor blockers. As with statin therapy, the greatest benefit was seen with long-term use of the antihypertensive medication, defined as more than 30 prescriptions. This analysis included more than 3600 cases of idiopathic Parkinson’s disease, and an equal number of matched controls, from the United Kingdom-based General Practice Research Database.

Calcium channel blockers may exhibit their neuroprotective effects by inhibiting certain types of calcium-dependent neuronal cell death seen in Parkinson’s disease. However, a study published a year earlier reported no association between Parkinson’s disease and calcium channel blockers.

There have also been studies to examine the link between high blood pressure and the risk for Parkinson’s disease. An epidemiological study reported a decreased risk of Parkinson’s disease associated with high blood pressure.

Currently, researchers do not know what causes Parkinson’s disease or how to prevent it. It is likely a combination of genetic factors, environmental influences, medications, and other diseases or illnesses. Countless studies have examined the risk of Parkinson’s disease as related to everything from drugs, diet, nutrition, weight, body mass index, bone mineral density, number of children, smoking status, and alcohol consumption. To date, however, the data is still conflicting as to the causes and risk factors for Parkinson’s disease.

References

Becker, C., Jick, S.S., Meier, C.R. (2008). Use of antihypertensives and the risk of Parkinson disease. Neurology, 70(Issue 16,Part 2), 1438-1444. DOI: 10.1212/01.wnl.0000303818.38960.44

Hu, G., Antikainen, R., Jousilahti, P., Kivipelto, M., Tuomilehto, J. (2008). Total cholesterol and the risk of Parkinson disease. Neurology, 70(21), 1972-1979. DOI: 10.1212/01.wnl.0000312511.62699.a8

Paganini-Hill, A. (2001). Risk Factors for Parkinson’s Disease: The Leisure World Cohort Study. Neuroepidemiology, 20(2), 118-124. DOI: 10.1159/000054770

Simon, K.C., Chen, H., Schwarzschild, M., Ascherio, A. (2007). Hypertension, hypercholesterolemia, diabetes, and risk of Parkinson disease. Neurology, 69(17), 1688-1695. DOI: 10.1212/01.wnl.0000271883.45010.8a

TON, T., HECKBERT, S., LONGSTRETHJR, W., ROSSING, M., KUKULL, W., FRANKLIN, G., SWANSON, P., SMITHWELLER, T., CHECKOWAY, H. (2007). Calcium channel blockers and ?-blockers in relation to Parkinson’s disease. Parkinsonism & Related Disorders, 13(3), 165-169. DOI: 10.1016/j.parkreldis.2006.08.011

Wahner, A.D., Bronstein, J.M., Bordelon, Y.M., Ritz, B. (2008). Statin use and the risk of Parkinson disease. Neurology, 70(Issue 16,Part 2), 1418-1422. DOI: 10.1212/01.wnl.0000286942.14552.51