A study reported in April 2018 has made the news because it suggests that taking a statin drug might increase your risk of getting a motor neuron disease. Statin drugs are used to reduce the amount of cholesterol in your blood, to prevent heart attacks and strokes. Motor neuron diseases include amyotrophic lateral sclerosis (ALS). ALS is also known as Lou Gehrig’s disease, because that famous baseball player had it. Physicist Stephen Hawking also had a form of ALS. Motor neuron diseases are a big deal, but so are heart attacks and strokes. So should you worry about this study? I don’t worry about it, for the following reasons:
- If you eat a healthy diet, you almost certainly won’t need pills to lower your cholesterol. So you could avoid even the theoretical risks of the side effects of the pills.
- Even if the statins do increase your risk of coming down with a motor neuron disease, the motor neuron diseases were rare to start with and are still rare, even though so many people are taking statins.
The decision of whether to take a statin drug should be based on your personal risk factors and the likely benefits. There are a few people who do have extremely high cholesterol for genetic reasons, even if they eat a good diet. They might benefit from a statin drug. For them, the high risks of dying of a heart attack or an ischemic stroke would probably outweigh the risks of developing a motor neuron disease.
What is Motor Neuron Disease?
The motor neurons are the nerve cells in the circuits that cause your muscles to move. The motor neurons in your brain are called upper motor neurons. The ones in your spinal cord are called lower motor neurons. Motor neuron diseases destroy your ability to control your muscles. You slowly lose your ability to use your arms and legs. Eventually, you lose the ability to talk, swallow, and even breathe.
Amyotrophic lateral sclerosis is one of the most famous motor neuron diseases. It is often called Lou Gehrig’s disease because it killed Lou Gehrig, who played baseball for the New York Yankees. He was called “The Iron Horse” because he played in 2,130 consecutive games, often while injured. However, he had to retire from baseball in 1939 after he got amyotrophic lateral sclerosis. He died of the disease in 1941.
The most famous recent person with a motor neuron disease was physicist Stephen Hawking. Hawking managed to live with the disease for 51 years.
High Cholesterol Is Dangerous
The purpose of the statin drugs is to reduce the amount of cholesterol in the bloodstream. If you don’t have high blood cholesterol, then you will not have atherosclerosis. If you have atherosclerosis, you may go on to have a heart attack or stroke. Heart attacks are our number 1 cause of death and disability, and strokes are number 3.
In other words, your total cholesterol has to be high for you to get atherosclerosis, but not everyone who has high cholesterol will get atherosclerosis. Also, not everyone with atherosclerosis will die of a heart attack or an ischemic stroke. Nevertheless, if you keep your total cholesterol stays below 150 mg/dL, you become practically immune to heart attack, and your risk of ischemic stroke also drops sharply.
How Diet Affects Cholesterol Levels
The best way to keep your total cholesterol this low is to eat a low-fat, zero-cholesterol, high-fiber diet. Our liver makes cholesterol to help us digest fat. This cholesterol is then absorbed back into the system and recycled. Foods from animal sources (meat, fish, dairy products, and eggs) also contain cholesterol. So when human beings eat a fatty diet and a lot of cholesterol-rich foods, their blood cholesterol can get very high. Dietary fiber is supposed to bind to cholesterol and carry it out of the body. So low-fiber diets make high cholesterol worse.
Human beings are at risk for atherosclerosis because our bodies were really built for a low-cholesterol diet. So even if we eat a low-fat, zero cholesterol diet, our cholesterol never gets too low. However, if we eat a fatty, cholesterol-rich diet, our total cholesterol can get too high. As a result, we can end up with cholesterol crystals in our gallbladders (gallstones). We can also end up with cholesterol deposits inside our arteries. The cholesterol builds up there because arterial walls are poorly drained by the lymphatic system. The coronary arteries (the arteries that serve the heart muscle) have particularly bad lymphatic drainage. That’s why so many Americans end up with clogging of the arteries.
Nearly everyone could keep their total cholesterol within the heart-attack-proof zone (<150 mg/dL) if they ate a low-fat, high-fiber, purely plant-based (vegan) diet. Yet many people are unwilling to do that. So for that reason, researchers developed cholesterol-lowering drugs. The statins keep the liver from making one of the ingredients that it needs for making cholesterol. However, it is better to eat a healthy diet, rather than to use pills to cover up the effects of a bad diet.
I explain all this in my book Where Do Gorillas Get Their Protein? What We Really Know About Diet and Health:
How Drug Safety Is Evaluated
If you invent a new drug, you have to do studies to show that the drug works and is reasonably safe. Otherwise, national governments won’t let you sell that drug within their country. Unfortunately, those studies generally compare the drug to a placebo (inactive pill), rather than to a dietary treatment, even if the most reasonable treatment is dietary.
In phase 3 of the drug development process, the drug sponsor has to run some large studies. Those studies must show that the drug actually works and that it is reasonably safe. However, those studies are too small to reveal rare side effects. They are too short to reveal the side effects of long-term use. For that reason, the U.S. Food and Drug Administration (FDA) keeps looking for safety problems, for as long as the drug is on the market. In particular, the FDA maintains the FDA Adverse Events Reporting System (FAERS). FAERS is a database of reports of bad things that happened to people who have taken a particular drug. This database is useful for uncovering “signals” that a drug might be causing a problem. Scientists need to do other kinds of studies to confirm whether those signals reflect something real.
Do Statins Cause Motor Neuron Disease?
For at least 10 years, scientists have worried that statins might be causing motor neuron diseases. Laboratory studies had shown that statins could harm spinal nerve cells that were being grown in a laboratory dish. This article discusses how the FDA began looking for evidence of whether statins were harming the spinal cord in living people. In October 2012, the review of the evidence existing at that time showed no relationship between statins and motor neuron diseases. However, the Golomb study suggests that people who are taking statins, especially the fat-soluble statins, probably do have a higher risk of motor neuron disease.
The people taking the water-soluble statins had about a 10-fold increase in the odds of having a motor neuron disease. The people taking fat-soluble statins had a 100-fold greater odds of having a motor neuron disease. Why they had greater odds in that study was not clear. Perhaps the statins really are causing the disease or making it progress faster. On the other hand, high cholesterol might protect people from getting the disease. Or there may be some odd reason why the motor neuron diseases in people taking statins were simply more likely to be reported. The answers are still not clear. However, this study might encourage doctors to avoid prescribing some statin drugs for people who have a family history of a motor neuron disease or who already have a neurological problem.
Is This a Big Increase in Risk?
This increase in odds sounds alarming. However, you should put it in perspective. The incidence of motor neuron diseases is roughly 2 cases per 100,000 people. A 10-fold increase would translate to 20 cases per 100,000 people. A 100-fold increase would translate to 200 cases per 100,000 people. So a big increase in the risk of a very rare disease does not necessarily mean a big risk for that disease.
If a blockbuster drug really does dramatically increase the risk of a rare disease, that rare disease would suddenly become much more common. For example, cigarette smoking was uncommon before World War I. Lung cancer was rare until the 1930s. Then, lung cancer suddenly became common. Most of the cases were in men who had taken up smoking during the war. Ultimately, scientists found convincing evidence that cigarette smoking really does cause lung cancer. In contrast, the research today is not trying to explain the massive outbreak of what was once a rare disease. Instead, they are trying to see whether a rare disease is more common among people who took a particular drug.
Sometimes there are outbreaks of motor neuron disease. For example, an outbreak in the East African country of Tanzania was found to be due to poorly processed cassava root, which was high in cyanide. The world’s highest rate of ALS was among the native people of Guam. Their high risk of ALS was due to a toxin from an algae. This toxin was in particularly high concentrations in fruit bats.
If statins really do increase your risk of getting a motor neuron disease, then the incidence of those diseases would have gone up in the United States after the statin drugs became commonly prescribed. The motor neuron diseases did become slightly more common from the 1950s to the 1980s. This increase was due to the aging of the population. More people were living long enough to get these diseases. Fortunately, despite the widespread use of statins, motor neuron diseases are still rare.
Photo by rchdj10