Do Statins Decrease Or Increase The Risk Of Parkinson’s Disease?

The Fine Print Behind The Misleading Headline

 Author: Dr. Stephen Chaney

 Human NeuronsI hadn’t paid much attention to the headlines saying “Statin Use May Decrease Parkinson’s Risk” until the other day when I happened to glance a couple of lines below the headline and spotted a statement saying “Study Shows That Discontinuation of Statin Therapy Increases Risk of Parkinson’s”.

 I immediately said to myself “That’s bizarre. There is a total disconnect between the headlines and the study.” If you really wanted to determine whether statin use reduced the risk of Parkinson’s, you would compare the incidence of Parkinson’s disease in a group of statin users and a matched group who did not use statins.

It turns out those studies have been done, and they were inconclusive – some studies showed a slight increase in Parkinson’s in statin users, some showed a slight decrease, and most showed no correlation between statin use and Parkinson’s.

In that context, this study could equally well have been interpreted as suggesting that statin use increased the risk of Parkinson’s, but somehow none of the headlines mentioned that possibility.

Are Both Possibilities Plausible?

 Let’s look at each possibility in detail. The reasoning is complex, but let me try to walk you through it.

 Could Statins Decrease The Risk Of Parkinson’s

 Parkinson’s is caused by the progressive degeneration of the brain neurons that produce a chemical messenger called dopamine that controls muscle movement. However, the causes of nerve degeneration in Parkinson’s patients are largely unknown.

Genetics may play a small role. Environmental toxins may play a role. But most experts feel that Parkinson’s patients produce an excess of free radicals, and it is the oxidative damage caused by those free radicals that results in the loss of the ability of neurons to produce dopamine.

But even that is not the whole answer. The brain is normally able to use coenzyme Q10, which is very abundant in brain, and other antioxidants to destroy free radicals before they damage brain neurons. Somehow in Parkinson’s patients free radical production and antioxidant production have gotten out of balance.

Advocates of the theory that statins may decrease the risk of Parkinson’s, point out that statins decrease oxidative damage. So if a person was predisposed to developing Parkinson’s and oxidative damage is a major cause of Parkinson’s, it is theoretically possible that statins could slow the progression to Parkinson’s while they were taking the drug. Of course, once they stopped taking the drug the oxidative damage to dopamine-producing neurons would resume and Parkinson’s would eventually develop.

In this model- Let’s call it Model A:

1)     Oxidative damage of dopamine-producing neurons was caused by some unspecified external agent.

2)     Statins protected the neurons from oxidative damage while they were being used.

3)     Once the statin drugs were discontinued oxidative damage resumed and the risk of developing Parkinson’s increased.

This is the model favored by the authors and repeated in all of the headlines you saw.

Could Statins Increase The Risk Of Parkinson’s?

Statins also interfere with the synthesis of cholesterol and coenzyme Q10, and these are both absolutely essential for brain function. Let’s start with cholesterol:

  •  20% of the body’s membrane cholesterol is found in the myelin sheath that coats the brain’s neurons (You can think of the myelin sheath as analogous to the plastic coating that insulates an electrical wire).
  • Cholesterol can’t cross the blood-brain barrier, which means that the brain cannot utilize cholesterol from the bloodstream . It has to make its own cholesterol.

As for coenzyme Q10:

  • It is not only a powerful antioxidant. It is also absolutely essential for cellular energy production.
  • The brain has tremendous energy requirements. The brain accounts for 20% of the energy utilization of our body. Neurons burn 2 times more energy than other cells in our body.

For both of these reasons, many experts have cautioned that statin drugs have the potential to cause neurodegenerative diseases such as Parkinson’s.  In this model – Lets call it model B:

1)     The statin drugs themselves are damaging the dopamine-producing neurons by inhibiting cholesterol and coenzyme Q10 synthesis in the brain.

2)     The antioxidant effects of the statin drugs were masking the damage caused by the statins while the drugs were being used.

3)     Once the statin drugs were discontinued the underlying damage was unmasked and the patients quickly developed Parkinson’s.

What Did The Study Actually Show?

The study (Lee et al, Neurology, 81: 410-416, 2013) looked at 43,810 statin users on the island of Taiwan. The Taiwanese Health System keeps extensive records of prescription use and health conditions of everyone on the island. It also requires that statin use be discontinued as soon as the patient reach their target of < 100 mg/dL LDL cholesterol, so they had the perfect population base to study what happens when you discontinue statin therapy.

The results were:

  • The patients who discontinued statin therapy were 42% less likely to develop Parkinson’s that those who continued on statin therapy. That result is consistent with both models A & B.
  • The increased risk of developing Parkinson’s when the drug was discontinued was only seen for the statin drugs like simvastatin and atorvastatin that are able to cross the blood brain barrier. That result is actually a bit more consistent with model B (Remember that the brain has to be able to make its own cholesterol and statins block cholesterol production).
  • When the study compared people using statin drugs to those not using statin drugs there was no significant difference in the prevalence of Parkinson’s – even for those statin drugs that cross the blood brain barrier. That means that merely being on a statin drug did not influence the risk of developing Parkinson’s. It was only when patients were on statin drugs for a period of time and were subsequently taken off statins that the risk of developing Parkinson’s was affected – and the effect was to increase risk! In the context of the first two findings, that result is also a bit more consistent with model B.

The Bottom Line:

If I were writing one of those medical blogs, I would have probably have gone with the party line and told you that statins decrease your risk of developing Parkinson’s. And if I were one of those health bloggers who never let the facts get in the way of a good story, I’d probably be scaring you with headlines saying that statins increase your risk of Parkinson’s.

But, I’m a scientist. I actually read the article, and I tell it to you like it is. Here’s your bottom line.

1)     Ignore the headlines. The study they are talking about can’t distinguish between statins increasing or decreasing the risk of Parkinson’s. Don’t let anyone tell you that reducing the risk of Parkinson’s is a side benefit of statin therapy. That simply has not been proven.

2)     The study does clearly show that discontinuing the statin drugs simvastatin and atorvastatin is associated with increased risk of developing Parkinson’s. That’s a big red flag for me, because 53% of patients discontinue statin therapy because of side effects, cost or other reasons.

3)     However, statin drugs do save lives, especially for people who have already had a heart attack, so talk with your doctor about the benefits and risks of statin drugs, and which statin drugs are best for you.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.