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Harvard Commentaries
Harvard Commentaries
Reviewed by the Faculty of Harvard Medical School

What Your Doctor Is Reading What Your Doctor Is Reading

Update From the Medical Journals: May 2013

May 31, 2013

By Mary Pickett M.D.

Harvard Medical School

May 31, 2013

What's the latest news in the medical journals this month? Find out what your doctor is reading.

Statins May Decrease the Positive Effects of Exercise

Statins are trusted medicines for lowering cholesterol. They are the most widely prescribed medicines in the United States. But is it possible that they might interfere with your physical fitness? A small new study suggests that taking a statin drug to lower cholesterol may reduce some of the positive effects of exercise. The study was published online by the Journal of the American College of Cardiology.

The study included 37 people who were overweight or obese. They were randomly divided into 2 groups. Both groups completed a 12-week program of almost-daily supervised exercise. One group also took 40 milligrams of simvastatin daily. After the 12 weeks, people who did not take statins showed a 10% improvement in their aerobic fitness. Those taking statins improved by only about 1%. To determine fitness, the researchers measured oxygen use during exercise. This is a measure of muscle activity.

Researchers also took biopsy samples of muscle tissue. Mitochondria activity in muscles increased by 13% for people who had been exercising without a statin. Mitochondria are the parts of cells that turn glucose (sugar) and oxygen into energy. Among those who took statins, on the other hand, mitochondrial activity decreased 4.5%.

Do statins blunt the benefits of exercise? Perhaps. The study is very small, and it was very short. But it adds to the evidence that statins are difficult on the muscles. The drugs can cause muscle aches in 5% or more of people who take them, regardless of how physically active a person is. In a previous study, Boston marathon runners who were taking statin drugs had a higher creatinine kinase (CK) level in their blood than runners who were not on statins. This was a sign of muscle stress or breakdown. In general, there is a higher rate of complaints about statin side effects among people who are involved in an "intense form of sport" than among less physically active patients.

Exercise is superb for heart health. Statins are also good for heart health. But what should you do if taking these medicines reduces the benefits you get from exercise? For starters, do not give up on exercise if you take a statin. Unless your doctor advises you to do so, don't stop your statin, either. So far, from what we know, people with heart disease who exercise and take statins are still better protected over the long term than those who do one without the other. This has been shown in a large study of veterans.

This new study lasted only 12 weeks and was very small. So we can't draw definite conclusions from it. We need to have a larger, long-term, placebo controlled study to see if the findings are repeated.

Even as we learn more about how statins may affect muscles, it is hard to argue with the proven benefits of these drugs. Statins are recommended for anyone who has had a prior heart attack or stroke. They are also recommended for people who are at very high risk for having a heart attack. This includes people who have multiple factors that increase their risk of heart disease. Still, it is bad news for statins. People who are at average or low risk for heart disease should be hesitant to start a statin.

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Changes to Mental Disorders Manual May Go too Far

Psychiatrists rely on the Diagnostic and Statistical Manual of Mental Disorders to diagnose a wide range of mental disorders. It lists criteria for every psychiatric illness. Psychiatrists have used the fourth edition of this book for almost 20 years. This month, a new edition, the "DSM-V," was published.

Many psychiatrists and other physicians have harshly criticized this updated version. The DSM-IV required fairly extreme symptoms before a person could be diagnosed with a psychiatric condition. By contrast, the DSM-V requires milder symptoms.

In this new version, grief is considered a form of major depression. Typical or normal events, such as temper tantrums in children and "senior moments" in older people, now have medical names, turning them into diagnoses. Some children who would not have qualified under DSM-IV will now qualify under DSM-V as having attention-deficit hyperactivity disorder (ADHD) or autism.

According to Dr. Allen Frances, the head of the task force that created the DSM-4 two decades ago, this new version will deceive Americans into thinking normal emotions are a sign of disease. "Normal needs to be saved from powerful forces trying to convince us that we are all sick," he said.

Critics have complained that the DSM-5 will:

  • Stigmatize people who should be considered normal
  • Lead to psychiatric medicines being prescribed to people who do not need them
  • Make it challenging to do research

With this amount of controversy, we can only hope that the committee working on the sixth version won't waste any time getting started.

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More News in Brief

  • During Hospital Stay, Heart Failure Patients Might Not Need to Restrict Salt and Fluid Intake. Keeping to a low salt diet, particularly one that includes strict limits on fluids, is difficult for heart failure patients. A small study suggests that hospitalized patients who are getting intravenous (IV) diuretic medicines may not need to follow this strict diet while they are in the hospital. The study was published online May 20 by JAMA Internal Medicine. 

    The study enrolled 75 heart failure patients who were hospitalized for edema (heavy, swollen legs and ankles or congested lungs) due to heart failure. Half of the patients were randomly assigned to have a limited diet (only 800 milliliters per day of fluid, and no more than 800 milligrams of salt per day). The other group did not have a special diet. Both groups received IV diuretics, which trigger urine production. The two groups lost weight with equal speed. After the hospital stay, all of the patients received the same instructions about fluid and salt intake. They had similar readmission rates to the hospital at 30 days. The main difference between the groups was that the patients who had to limit their fluids and salt intake complained more of feeling thirsty when they were in the hospital.

    This study suggests that limiting fluids and salt while being treated with IV diuretics in the hospital makes too small a difference to be practical. However, limiting salt intake outside of the hospital has been linked with better heart failure control. For example, heart failure patients whose diets are lowest in salt are hospitalized less often than those whose diets are moderate to high in salt. This study should not change our practice for patients who are managing heart failure out of the hospital.

  • New Guidelines Say Doctors Should Screen All Adults for 'Risky' Drinking. The U.S. Preventative Services Task Force says primary care doctors should ask patients about their drinking and offer counseling to those with risky drinking behavior. There is clear evidence that brief counseling from a primary care doctor -- even a short conversation -- can help some drinkers cut down. The task force suggests that doctors ask women or people older than 65, "How many times in the past year have you had four or more drinks in a day?" For men, it's five or more drinks in a day.
  • Pregnancy Bed Rest Does Not Help and Might Harm. Almost 1 out of 5 pregnant women has been told to limit activity or go on bed rest at some point during pregnancy to prevent premature birth. But new research suggests that bed rest does not seem to prevent premature births, and it may even worsen that risk. The report was published May 14 in Obstetrics and Gynecology. 

    In this study, about 250 women received care after being diagnosed as having a "short cervix" — a condition that often leads to bed rest. The women were asked to either limit sexual activity, reduce or stop work, or go on bed rest. These women reported back to the researchers how well they followed the advice. When birth events were compared, 37% of women who took the advice of staying on bed rest had a premature baby. Only 17% of women who decided not to follow the bed rest advice had a premature baby. 

    This study was not a randomized study, so it leaves room for doubt about the results. But it is the best evidence we have. Women should not be advised to go on bed rest unless they are participating in a randomized research study, according to one expert who reviewed this study. We may be on our way to proving that bed rest is not beneficial. Instead, it is "bunk."

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Mary Pickett, M.D. is an associate professor at Oregon Health & Science University where she is a primary care doctor for adults. She supervises and educates residents in the field of Internal Medicine, for outpatient and hospital care. She is a Lecturer for Harvard Medical School and a Senior Medical Editor for Harvard Health Publications.

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