We've seen this many times before. One day doctors say X, Y and Z are good for you, only to change their minds a few months or years or decades later. How do we ever know what to believe? There's really no answer to this, of course. Physicians and other medical professionals work hard to learn all about the human body and how it responds to everything from food and exercise to drugs, tests and medical interventions. Sometimes their advice is good, sometimes it's bad, sometimes it's neutral.
Although the 21st century is still in its infancy, doctors have already changed their opinions on many things. Here are 10 of the more prominent medical issues where they've rethought conventional wisdom -- or at least they're vigorously debating it. Because even doctors can't always agree with one another.
For decades, women were urged to have annual mammograms -- tests that screen for breast cancer and abnormalities -- starting at age 40, and then yearly afterward. Most women don't exactly enjoy undergoing a mammogram, as the standard film test involves squishing your breasts in between two plates. So women rejoiced to hear the latest medical thinking: that they may not need mammograms quite that frequently.
The U.S. Preventive Services Task Force in 2009 updated its recommendations to biennial film mammograms and only for women ages 50-74. The reason for the change? The Task Force says studies show that while mammograms do a good job detecting early-stage breast cancer, they don't spot advanced cases any earlier. False positives, common in mammography, are also more typical in those 40-49; these erroneous results can cause much anxiety, plus unnecessary additional procedures such as more imaging or biopsies. Finally, some of the women diagnosed with early-stage breast cancer and subsequently treated may not have needed the treatment, as their cancer may have been slow-growing and would never have resulted in death.Screening every other year, says the Task Force, maintains the benefits of mammograms while reducing its harmful effects by nearly half [sources: U.S. Preventive Services Task Force, Pruthi].
While the evidence may seem compelling, not everyone agrees. The American Cancer Society, for example, continues to push for yearly mammograms starting at 40 [source: Pruthi]. Best advice? Consult with your physician and make your own decision.
Marijuana is the most common illicit drug used in the U.S., although the federal government classifies it as a Schedule I substance. This means it has no medicinal uses and carries a high risk for abuse.
Studies show that when young people are heavy users, IQ loss often results. Smoking weed also carries the same risk as cigarette smoking: constant coughing, lung irritation, susceptibility to lung infections and cancer [source: National Institute on Drug Abuse ].
However, people have long clamored for the government to allow marijuana to be used for medicinal purposes, citing its help in treating seizures, medication-induced nausea and chronic pain from injuries. But physicians ignored these pleas, insisting the drug was far too dangerous.
Since 1996, some 20 states have passed laws allowing marijuana's use for medicinal purposes, and medical professionals are witnessing its often-positive results. As a result, many physicians are changing their minds about legalization. Dr. Sanjay Gupta and Dr. Mehmet Oz are two prominent physicians who say they now support medical marijuana [source: Baca]. Gupta, for one, said in 2013 that he should have considered some of the "remarkable research" coming from smaller labs in foreign countries, plus the scores of patients testifying to how much medical marijuana helped their symptoms before making his decision. And in a 2014 survey, 56 percent of physicians said medical marijuana should be legalized nationwide [source: Rappold].
People who are transgender -- that is, those who self-identity doesn't match their biological sex -- were long classified as having a psychological disorder. Specifically, the American Psychiatric Association called the condition "gender identity disorder" and added the term to its Diagnostic and Statistical Manual of Mental Disorders, or DSM, in 1980 [source: Glicksman]. Although assigning transgender people this label ensured they had access to medical care, the term "disorder" carried a certain stigma.
In the fifth edition of the DSM, published in 2013, the term "gender identity disorder" was replaced with "gender dysphoria," a less stigmatizing term [source: Lowder]. This is an acknowledgement that being transgender is simply something that can happen to human beings. It's not a disorder in and of itself. You can be transgender and not seek or need treatment of any sort. However, if you have such intense distress being in the "wrong" body that you want to transition to the male or female form, that is considered having gender dysphoria. Physicians with transgender patients who have gender dysphoria are generally required to first be assessed by a mental health professional before undergoing any kind of medical intervention.
Value of Saturated Fats
Saturated fats were given the heave-ho in the 1970s, when a landmark study linked coronary heart disease with high levels of total cholesterol. People were advised to reduce their fat intake to 30 percent of total calories and limit saturated fats to a mere 10 percent[source: Willey]. Reduced-fat products flooded the market -- remember Snackwell cookies, anyone? -- and we gobbled them up.
In 2014, some doctors say that was possibly the worst medical advice given in the past 40 years [source: Willey]. People gorged on low-fat products, which typically had loads of extra sugar to compensate for the flavor lost when saturated fats were lessened or removed. Obesity became an enormous problem. (The obesity rate among U.S. adults has more than doubled since the 1960s, from 13.4 to 35.7 percent [source: National Institutes of Health].) And heart disease didn't diminish. Additional studies haven't shown any significant link between saturated fats and higher risks of cardiovascular disease [source: Willey].
The current advice is to eat your fruits and veggies, eat healthy fats like those found in avocados, nuts and seeds, and enjoy saturated fats -- like meat, cheese and eggs -- in moderation. It's the fats that keep you feeling fuller longer, and less prone to snacking. And when you do snack, pass on the sugary, highly-processed foods [source: Northrup].
Hormone Replacement Therapy
Menopausal women were overjoyed when hormone replacement therapy (HRT) was first rolled out in the early 20th century. After all, bolstering their declining estrogen levels with synthetic versions helped reduce hot flashes, mood changes and other annoying symptoms of menopausal and postmenopausal life. By the late 20th century, HRT doses were tailored to each woman, included progesterone and lower doses of estrogen, and were viewed as a way to combat osteoporosis. Vast numbers of menopausal women were taking HRT.
Then in 2002, a large hormone trial conducted by the U.S. Women's Health Institute (WHI) was stopped early when it overwhelmingly showedHRT could cause heart disease, stroke, blood clots and breast cancer if taken on a long-term basis. Women worldwide panicked and stopped HRT [source: Bouchez]. But subsequent studies in the U.S. and U.K. say the issue is a bit more complex.
The original WHI study looked at women from age 50 to 79 and lumped their results together. Yet most of HRT's harmful results occurred in the older women studied, not the typical HRT patients -- women in their late 40s or early 50s.In 2012, international experts said HRT actually poses few risks for women in the latter age group [sources: Bouchez, Hope].
Today most physicians recommend using HRT if it's needed, but for the shortest time possible, assuming you have no particular health risks.
Pulmonary Artery Catheters
Since its introduction in 1970, patients who landed in a hospital's intensive care unit (ICU) were often given a PAC, or pulmonary artery catheter. The catheter, threaded into the right side of the heart via a blood vessel in the neck or groin, was a monitoring device that measured the pressure in the patient's heart and lung blood vessels [source: NCIB]. By 1986, 20 to 40 percent of all ICU patients got one -- surprising, since the device's safety, accuracy and benefits were never proven [source: Marik].
Although complications from the use of a PAC were uncommon, and PAC-associated deaths rare, patients sometimes suffered from bleeding in the lung and changes in heart rhythm [source: NCIB]. Eventually, studies from 1990s and early 2000s showed the routine use of a PAC with patients in shock was actually inferior to less-invasive strategies, as the PAC could be unreliable and inaccurate and did not improve patient outcomes. Further, newer devices were developed that produced better results and were less invasive. In 2014, the device is rarely used on patients in shock [source: Marik].
Asperger's Syndrome and Autism
Asperger's syndrome was officially recognized in 1994, when it was added to the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders(DSM), the diagnostic guide recognized by the American Psychiatric Association. Although sometimes referred to as a high-functioning form of autism, the guide specified Asperger's was a distinct disorder [source: Hamilton]. Those with Asperger's have a hard time interacting with others and often are intensely interested in a particular topic, say trains, talking about them nonstop. While autism is also a developmental disorder, its symptoms are more pronounced. Autistic people tend to have more difficulty interacting with others -- sometimes they simply can't -- and often exhibit repetitive behaviors, such as flapping their arms or rocking.
In 2013, the DSM's fifth edition was published. Asperger's and autism were merged into the guide's new "autism spectrum disorder" category. The change was one of the most controversial in the new DSM-5 [source: Parry]. While many people with Asperger's don't see themselves as autistic at all -- most can function independently in society -- the broader category was seen by health care professionals as more reliable. Previously, when trying to diagnose a patient with one of these disorders, clinicians mainly relied on the patient's language skills. Reasonably good skills could mean Asperger's; less-developed ones might mean autism [source: Hamilton]. But that's a subjective call, and someone's language skills can change over time. With one category, the hope is to focus on how to best help the patient, not the specific label.
Body Mass Index (BMI)
Back in the old days, doctors looked at life insurance tables to determine healthy weights for patients. These listed healthy weight ranges for men and women based on their heights. But life insurance companies had their own tables, and they weren't always the same. So in 1998 the National Institutes of Health unveiled the Body Mass Index (BMI) as a way for everyone to figure out healthy weights in the same manner. To calculate someone's BMI, you divide the person's weight in pounds by his height in square inches, then multiply the result by 703. A good BMI is 18.5-24.9, according to the National Institutes of Health, while a BMI of 25-29.9 means you're overweight. Anything 30 or more? Obese. BMI was quickly adopted by most health professionals [source: Zelman].
In 2014, the BMI was under fire because it doesn't factor in your age, gender or muscle mass. There's also no distinction between lean and fat body mass. Basketball superstar Michael Jordan, for example, had a 27-29 BMI in his prime -- meaning he was overweight -- despite sporting a chiseled frame and less-than-30-inch (76-centimeter) waist. Similarly, elderly people on the roly-poly side might have normal BMIs because they've lost muscle mass, and muscle weighs more than fat. Many health professionals now say you should use BMI as just one measure of health and fitness, along with factors such as body fat percentage, waist circumference and level of physical activity [source: Zelman].
Stenting for Stable Coronary Artery Disease
If you develop stable coronary artery disease, also called stable angina, you'll notice chest pain when you exert yourself. This is because your arteries are narrow or blocked, reducing the amount of oxygen-rich blood your heart can receive. The pain will go away when you rest and reoccur when you exert yourself the same amount and/or the same amount of time.
Today's standard treatment for stable angina includes lifestyle changes (such as quitting smoking, losing weight and exercising) and medications, including aspirin, beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, angiotensin-receptor blockers and statins. But as recently as 2006, many patients with stable angina were also given stents, which are tubular supports that prop open your narrowed or blocked arteries, allowing more blood to reach your heart [source: Mitka]. Stents are placed during a procedure called angioplasty.
Stents are great when used in those who have had a heart attack or develop unstable angina, which is chest pain that occurs suddenly and frequently with little or no exertion. But studies dating from 2007 revealed stents don't offer any additional help at all if you've got stable angina. All you need are some lifestyle changes and maybe some of the medicines listed above [source: Mitka]. Good news for those who hate to go under the knife.
Use of Pain Pumps in Joints
In the late 1990s, orthopedic surgeons began using pain pumps in some of their procedures. The postsurgical devices pump local anesthetics through a plastic tube to a specific area of the body for pain relief. By inserting pain pumps after surgery, patients were able to avoid long hospital stays. The pumps were also considered safer for pain relief than prescription narcotics [source: Thomas]. Although the Food and Drug Administration (FDA) never cleared the use of pain pumps in joints, surgeons eventually began using them in shoulder surgeries, and to a lesser extent in knee surgeries. (Physicians are permitted to use FDA-approved devices in such an "off label" fashion, which means for another purpose than that which the FDA originally indicated.)
But after they started using the pumps in joint surgeries, orthopedic surgeons began noticing many young, active patients developing post-surgical chondrolysis, a rare ailment where joint cartilage dies. The pain pumps and their medications were blamed. Those in the medical profession now say exposing sensitive cartilage to local anesthetics for up to 72 hours can destroy the cartilage, and most surgeons no longer use them in this fashion. The FDA now also requires pain pump and local anesthetic manufacturers to warn against use in joints [source: FDA].
Researchers say they've found a way to treat appendicitis with antibiotics. HowStuffWorks looks at the new research.
Author's Note: 10 Things Doctors Have Completely Changed Their Minds About This Century
My older daughter had a pain pump inserted into her knee after ACL surgery and developed chondrolysis at the age of 18. She was told to expect a knee replacement as soon as she's old enough (about 40). Hopefully all surgeons have stopped using these devices in joints.
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