Parkinson's disease is a neurological condition affecting the "substantia nigra," a small area of cells in the mid-brain. Degeneration of these cells results in lower levels of the neurotransmitter dopamine (a brain signaling chemical) and upsets the balance between dopamine and another brain chemical, acetylcholine. The most familiar signs of the disease are resting tremors, a generalized slowness of movement, stiff limbs, and problems with balance or gait. Depression is also common. In advanced cases, mental function can deteriorate. Parkinson's disease is progressive and incurable.
A small study from the University of North Carolina (UNC) at Chapel Hill suggests that people with low LDL (low density lipoprotein, the "bad" cholesterol) are more likely to develop Parkinson's than those whose LDL is high. (As far as your heart is concerned, low LDL is good – the lower it is, the lower your risk of heart disease.) The North Carolina researchers tested the cholesterol of 124 Parkinson's patients being treated at the UNC Movement Disorder Clinic and 112 spouses of clinic patients. They found that those with LDL levels of less than 114 (mg per deciliter) had a 3.5 times higher incidence of Parkinson's than study participants whose LDL was more than 138.
However, we don't know whether the Parkinson's patients' LDL was low before the onset of the disease. The researchers did determine that study participants with Parkinson's were less likely to have taken cholesterol-lowering drugs than those in the control group.
While these findings are interesting, the investigators described their findings as preliminary and called for larger studies to help clarify how LDL affects Parkinson's risk. In the meantime, if your LDL cholesterol is high, you should follow medical advice to bring it down. After all, it's long been known that smoking is linked to a lower risk of Parkinson's but it's certainly not a good idea to take up cigarettes to protect yourself from the disease. Keep the relative risks in mind: the incidence of Parkinson's disease is 12 to 20 cases per 100,000 persons per year. The incidence of heart disease is one in 12.
Andrew Weil, M.D.