NEFROLOGÍA Y UROLOGÍA
IPRATROPIO CON SALBUTAMOL
Obesity
Being overweight predisposes the body to heart disease, but that’s only one way that obesity can affect longevity and accelerate aging. New research suggests that it also makes cells older on a
molecular level. For instance, some of the same researchers that looked at telomere length in active and sedentary twins also looked at telomere length in obese women. What they found was that obese women had shorter telomeres than lean women. If you translated the
telomere length into years, the obese women’s cells were nine years older than the lean women’s. Excess body fat is also thought to cause oxidative stress and is known to promote inflammation of the kind that’s been linked to age-related diseases.
Inflammation caused by excessive body fat may also be related to the shrinking of the brain. Gary Wenk, PhD, a professor of psychology, neuroscience, and molecular virology, immunology, and medical genetics at the Ohio State University and Medical Center, has shown that proteins that are a by-product of inflammation can cause regions of the brain responsible for memory and
Other studies have shown that older people who are obese have lesser cognitive and memory capabilities and are at an increased risk for Alzheimer’s disease.
Another way that obesity affects aging is by contributing to insulin resistance. Insulin is the hormone charged with ushering the sugar from your blood into cells throughout your body. When you aren’t producing enough insulin, or your cells become resistant to insulin’s actions, blood sugar rises. People with type 1 diabetes produce no insulin. People with type 2—the kind that is often caused by too much body fat and constitutes about 90 to 95 percent of
diabetes cases—are insulin resistant. That is, their bodies don’t respond
properly to normal amounts of insulin so that sugar doesn’t get adequately
transported from the blood to the cells. People with type 2 diabetes may even eventually stop producing normal amounts of insulin, which can make the situation worse.
Insulin resistance can shorten your life span and hasten aging in a number of ways: it encourages inflammation,
quashes sirtuin activity (sirtuins are enzymes that delay cell death), shortens telomeres, and raises levels of
compounds called AGEs—advanced glycation end products—that wreak havoc in the body (see here). Besides
obesity (and particularly an
overabundance of intra-abdominal fat— stored fat that surrounds the organs), a diet high in sweets, sodas and other sugary drinks, white bread, white rice, and other processed grains seems to promote insulin resistance. There’s a hereditary factor to insulin resistance as well—your genes may make you more susceptible. But you might be able to stave it off for longer, and if you get it, regulate your blood sugar better, with the type of diet you’ll find in chapter 3.
Smoking
While the link between excessive body weight and aging is disheartening given
the rates of obesity in this country, it’s somewhat more surprising than what has long been known as the number one cause of preventable death: smoking. Besides its deleterious effect on life span, smoking promotes aging in just about every way imaginable. It’s known, for instance, that smoking creates free radicals and that it’s associated with the development of many age-related
diseases, including some that you might not even think would be related:
osteoporosis, diabetes, and the eye disease macular degeneration. In the obesity study I mentioned earlier, they also looked at the effect of smoking on telomeres and found that it shortened telomere length by a full 18 percent.
It’s been known for some time that smoking is linked to dementia, and recently researchers at Kaiser
Permanente in Oakland found that it’s also associated with an increased risk of Alzheimer’s disease. Compared to
nonsmokers, people who smoked two packs a day in midlife increased their risk of Alzheimer’s by 157 percent.
Dr. Lancer will talk more about the effects of smoking on the skin in chapter 4. However, suffice it to say that there’s such a thing as “smoker’s face,”
characterized by deep lines around the mouth and eyes and a grayish tint to the skin. Nicotine contracts the blood vessels, decreasing blood flow to the
skin and all the other major organs in the body.
There are a few other reasons why it’s to your advantage to quit smoking. One is that it makes it difficult to exercise at the pace you need to get sizable anti-aging benefits. The other is that smoking can interfere with sleep. To see just how much, researchers at the Johns Hopkins University School of Medicine hooked up forty smokers and forty nonsmokers to monitoring machines and looked at their brain waves as they slept. The smokers spent a lot less time in deep sleep, the most rejuvenating kind of slumber, and a lot more time in the lighter stages of sleep, when it’s easy to be awakened—possibly in part because
they were going through nicotine withdrawal while they slept. The smokers also reported feeling less refreshed in the morning. (You’ll learn more about the importance of a good night’s sleep in chapter 5.) Smoking is certainly one of the worst things you can do to yourself—it’s like lying on a train track when you know that the train is coming. Quitting, on the other hand, is perhaps the single best thing you can do for yourself.
Stress
Work, finances, kids’ schedules,
relationship problems, sick parents, your own health issues—there are so many
sources of stress in our modern daily lives. When you experience stress, your body releases powerful chemicals and hormones, including one called cortisol, that prepare your body to fight or flee a perceived threat or danger—the “fight or flight” response. “That response creates a biochemical soup that changes the chemistry of our blood,” explains Elissa Epel, PhD, associate professor in the department of psychiatry at the
University of California, San Francisco. The fight or flight response is
beneficial in the short run; it helps us deal with a variety of dangerous situations. After the threat has been resolved, hormones level off and your body goes back to baseline. But if these
high levels of stress chemicals persist— as they often do when someone is living a high-pressure life—they can be
harmful. Instead of protecting the body, they can cause damage to molecules and tissues and lead to a weakened immune system, acne, and other problems,
including increased intra-abdominal fat, the kind that puts the body at risk for stroke, heart disease, and high blood pressure. The stress response also triggers higher levels of damaging free radicals, inflammation, and, in some cases, even spikes in insulin and glucose levels that make the body seem
prediabetic. And all of these, not surprisingly, can speed up the aging
process.
Prolonged stress can also be
extremely harmful to the brain. Studies have shown that persistent stress can cause depression and anxiety. It can kill brain cells and damage the
hippocampus, the area in charge of memory and learning (research suggests stress actually shrinks this portion of the brain). When damaged, the hippocampus cannot create new memories or access stored ones as efficiently. And because the hippocampus is part of the system that signals the body to stop producing cortisol, levels of the stress hormone can remain out of control and continue to harm the body.