Vonnies Health Spot

REVERSE BRAIN ATROPHY WITH EXERCISE?

Science told us in the past that we’re born with all the brain cells we will ever have (the moral of the story being “take care of what you’ve got, because you ain’t gonna get no more”). Well, surprise, surprise! New research shows that the old tale is not true.

In the late 1990s, several lines of research began turning investigators’ concepts of mood disorders upside down.

BRAIN CELL REGENERATION
Research showing that neurogenesis—the birth of new brain cells—can continue throughout life. They have found that the process of neurogenesis is an ongoing one, with new brain cells being born even as old brain cells die off. Researchers have also found that depression appears to inhibit this birth of new brain cells. In animal studies, stress puts a halt to the process of neurogenesis. Under stress, existing cells shrink and the total number of cells decreases. Exercise and “environmental enrichment,” on the other hand, have a beneficial effect. In humans, there are hints that exercise may help reverse brain atrophy.

THE ROLE OF DEPRESSION
People who’ve had depression are likelier to have a smaller hippocampus (a part of the brain that plays a role in emotion and is associated with memory and learning). The more severe and long-lasting the depression, the greater the loss of brain volume. This process of brain atrophy also affects the frontal lobes, which are involved in managing emotional reactions. The good news is that most of the change seems to be related to cell shrinkage, rather than outright cell death, and thus can potentially be reversed.

HOW DO ANTIDEPRESSANTS HELP?
What about the familiar neurotransmitters such as serotonin and norepinephrine? They are still understood to play a significant role in mood disorders—but with a new twist. Most people are familiar with the research that underlies the use of fluoxetine (Prozac) and similar antidepressants. These drugs block the reuptake of certain neurotransmitters at receptor sites in the brain, thus increasing the concentrations of serotonin and other neurotransmitters in the synapses (gaps) between cells in the brain. This increase is believed to be responsible for the elevation of mood.

PROMISING DISCOVERIES
The twist? More recently, instead of focusing on tinkering with the level of neurotransmitters between cells, researchers have looked at what happens when the neurotransmitter binds to the cell membrane. The reactions that then go on inside the cell are now thought to be more important to the cell’s functioning than the binding of the neurotransmitter to the outside. For instance, researchers have found that antidepressants increase levels of brain derived neurotrophic factor (BDNF), which helps nourish neurons, helping them become more active and make more connections to other cells. Researchers also have found that antidepressants are involved in neurogenesis—at least in rats, increasing the production of new neurons in the rat hippocampus.

THE CAVEAT
The extent of the response varies among individuals and may be moderated by how severe a person’s depression has been, and how often it has recurred. And psychotherapy still has a role to play because how we interpret a stressful event can have a significant impact on our emotional response and ability to recover.

The above was excerpted from The Anatomy of Mood -- Biology and the Brain, published by Johns Hopkins Medical Research Hospital. For more information, go to www.johnshopkinshealthalerts.com.

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In a recent comment, Tim Wang asked about whether I plan to publish a collection of the posts I have authored in the past and the answer is yes! Watch for the first volume of Vonnies Health Spot to appear by the end of January 2008! Soon there will also be CDs available and in the future we hope to produce DVDs of health lectures and exercises.

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Disclaimer: The purpose of this weblog is not to dispense medical advice nor in any way is meant to be construed as diagnostic or prescriptive. Always check with your physician before beginning any new program or trying any of the items discussed in the posts that appear on this site.

DON’T BELIEVE EVERYTHING YOU HEAR

The following ideas are scientifically correct, right?

>People should drink at least eight glasses of water a day
>People use only 10 percent of their brains
>Eating turkey makes us sleepy
>Shaving hair causes it to grow back faster and coarser
>Reading in dim light ruins your eyesight
>Hair and fingernails continue to grow after we die

Wrong. These are some commonly held medical myths that have been around as long as some of us have lived and longer. At Indiana State University School of Medicine researchers decided to investigate some myths that most of us have grown up with.

“We got fired up about this because we knew that physicians accepted these beliefs and were passing this information along to their patients. And these beliefs are frequently cited in the popular media,” says co-author Aaron Carroll, MD, MS, assistant professor of pediatrics and a Regenstrief Institute, Inc. affiliated scientist.

Co-author Rachel Vreeman, MD, a pediatrics research fellow, says, “Whenever we talk about this work, doctors at first express disbelief that these things are not true. But after we carefully lay out medical evidence, they are very willing to accept that these beliefs are actually false.”

>People should drink at least eight
glasses of water a day
The first belief they explored, that people should drink at least eight glass of water a day has been promoted as healthful as well as a useful dieting or weight control strategy.

“When we examined this belief, we found that there is no medical evidence to suggest that you need that much water,” said Dr. Vreeman. The myth can be traced back to a 1945 recommendation from the Nutrition Council that a person should consume the equivalent of eight glasses (64 ounces) of fluid a day. But an important part of the Council’s recommendation has been lost over the years—the large amount of fluid contained in food, especially fruits and vegetables, as well as in the coffee and soda people drink each day should be included  as part of the 64-ounce total. And conversely, the study authors noted that drinking excess water can be dangerous, resulting in water intoxication and even death.

>People use only 10 percent of their brains
This statement has been erroneously credited to Albert Einstein and is often cited by everyone from physicians to popular comedians. The study authors found that there are a lot of ways to disprove this belief. MRI scans, PET scans and other imaging studies show no dormant areas of the brain, and even viewing individual neurons or cells reveals no inactive areas of the brain. Metabolic studies of how brain cells process chemicals show no nonfunctioning areas.

Carroll and Vreeman think this myth probably originated with self-improvement experts in the early 1900s who wanted to convince people that they had yet not reached their full potential. By paying these possible descendants of snake-oil salesmen, one was supposed learn how to be able to tap into the 90 percent not being used.

>Eating turkey makes us sleepy
Both Dr. Vreeman and Dr. Carroll admit that they believed that eating turkey makes one especially drowsy. Scientific evidence supports that tryptophan, which is contained in turkey, can cause drowsiness. But they found that turkey doesn’t contain an exceptional amount of tryptophan. In fact, turkey, chicken, and ground beef contain about the same amount of tryptophan. Protein sources like pork and Swiss cheese contain more tryptophan per gram than turkey.

So why do people believe eating turkey makes them sleepy but never feel that way after a burger or pork chop? Again, this is a belief that the media, and other pop culture icons frequently repeat, popularizing the myth in spite of the easily accessible data on percentage of tryptophan in various products. Most likely, according to the study authors, this myth gained credence because turkey is often consumed during large, heavy dinners. It’s the total content of the meal that makes one feel lethargic.

>Reading in dim light ruins your eyesight
Even before Abe Lincoln was told that reading in dim candlelight was bad for his eyes, people have believed that reading in dim light causes permanent eye damage. Generation after generation of parents have warned children (future physicians included) caught reading with flashlights under their blankets that reading in poor light ruins your vision. The study authors found no evidence that reading in dim light causes permanent eye damage. It is true, they say, that eyestrain can occur in dim light, causing some temporarily decreased acuity, but after the are rested the eyes return to their full potential.

>Shaving hair causes it to grow
back faster and coarser
The two researchers also explored a frequently held belief related to hair—that shaved hair grows back faster, coarser and darker. They found a 1928 randomized clinical trial, which compared hair growth in shaved patches to growth in nonshaved patches. The hair that replaced the shaved hair was no darker or thicker, and didn’t grow in faster. So why has this myth persisted almost 80 years after it was disproved and in the light of more recent studies which confirm the 1928 work? Again, optical illusions may be partially responsible, according to the study authors. When hair first comes in after being shaved, it grows with a blunt edge on top. Over time, the blunt edge gets worn so it may seem thicker than it actually is. Sun naturally bleaches hair over time, so hair, which is just emerging after an individual has shaved seems darker, but actually is no darker than any new hair growth.

>Hair and fingernails continue
to grow after we die
Another hair-related myth is that fingernails and hair grow after death. Most physicians the study authors queried initially assumed this belief was true. But when they thought about it, they knew it couldn’t possibly be valid. This myth likely persists because of an optical illusion—and because it’s just so creepy.

A Lighthearted Way of Teaching Future Experts to Question Common "Knowledge"
Why have these myths been perpetuated? Dr. Carroll and Dr. Vreeman believe it’s because they are repeated to us by experts. “Until someone takes the time to question and look for evidence, medical myths will remain accepted beliefs. We have tried to show through science and research why certain widely accepted beliefs are untrue. To some extent this is what we do in our regular jobs every day, teaching medical students and residents (physicians in training) to question what they hear,” said Dr. Carroll. “This study was a lighthearted way to remind people that first they might believe things because they have heard them from other people, especially from experts; and second, staying current is not just a matter of adding new knowledge onto the things we already believe. Sometimes you really have to look back on things already in your head or things you already believe to be true and reinvestigate or investigate for the first time whether those things [really] are true,” said Dr. Vreeman.

Dr. Vreeman and Dr. Carroll, who are with Children’s Health Services Research in the IU School of Medicine’s Department of Pediatrics, are currently working on a book examining dozens of other popular medical beliefs to see if they are true, false or unproven. So was your mother correct when she said your chewing gum would stay in your stomach for seven years? Dr. Carroll and Dr. Vreeman, both pediatricians with Riley Hospital for Children, one of the nation’s leading centers of excellence in pediatric medicine, will let you know in 2008.

This research, entitled “Medical Myths Even Doctors Believe” was published in the Christmas issue of the British Medical Journal.

Adapted from materials provided by Indiana University.

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Disclaimer: The purpose of this weblog is not to dispense medical advice nor in any way is meant to be construed as diagnostic or prescriptive. Always check with your physician before beginning any new program or trying any of the items discussed in the posts that appear on this site.

THE POSSIBILITY OF DEVELOPING THE BIG C FRIGHTENS EVERYONE, SO MYTHS ABOUND

According to a recent survey by the American Cancer Society and published in its journal Cancer, many people hold a lot of beliefs about cancer that are based in urban mythology and not on solid science. For example:

>More than 14 percent thought that shampoos and antiperspirants cause cancer; 15 percent weren’t sure.

>More than 15 percent incorrectly believe that smokers do not reduce their risk of cancer by quitting, or they believe that low-tar cigarettes are safer.

>Nearly 30 percent said they thought electronic devices cause cancer; 25 percent weren’t sure.

>Almost 40 percent said they thought pollution was a greater risk for lung cancer than smoking; another 19 percent weren’t sure.

Ironically, the survey found that the segment of the population most likely to hold misconceptions were older, less educated males who rated themselves as “very informed.”

Many people have a hard time judging risk. They hold unproven or disproved theories about risk avoidance and health. Some urban myths that will not go away include: underwire bras, cell phones or antiperspirants as cancer causes. Yet, on the other hand, people often ignore or minimize the big risks. Though the Internet is a great resource for information, it can also be a source of rumors and misinformation. Make sure the websites you visit are reliable.
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Disclaimer: The purpose of this weblog is not to dispense medical advice nor in any way is meant to be construed as diagnostic or prescriptive. Always check with your physician before beginning any new program or trying any of the items discussed in the posts that appear on this site.