Saturday, October 31, 2015
Dating a cell's age is tricky, because its biological and chronological ages rarely match. A cell could be relatively young in terms of how long it has existed but function slowly or erratically, as if elderly.
Today, many scientists have begun determining a cell's biological age — meaning how well it functions and not how old it literally is — by measuring the length of its telomeres.
For those of us who don't know every portion of our cells' interiors, telomeres are tiny caps found on the end of DNA strands, like plastic aglets on shoelaces. They are believed to protect the DNA from damage during cell division and replication.
As a cell ages, its telomeres naturally shorten and fray. But the process can be accelerated by obesity, smoking, insomnia, diabetes and other aspects of health and lifestyle.
In those cases, the affected cells age prematurely.
However, recent science suggests that exercise may slow the fraying of telomeres. Past studies have found, for instance, that master athletes typically have longer telomeres than sedentary people of the same age, as do older women who frequently walk or engage in other fairly moderate exercise.
The U.S. death rate for all causes is continuing to decline, aided by drops in fatalities from leading causes like heart disease, cancer, stroke, diabetes and accidents, new research finds.
Between 1969 and 2013, the death rate for all causes declined 43 percent from about 1,279 people for each 100,000 individuals in the population to about 730 per 100,000, according to the study published today in JAMA, the journal of the American Medical Association.
Five of the six leading causes of death declined during the study period. Death rates dropped 77 percent for stroke, 68 percent for heart disease, 40 percent for unintended injuries, 18 percent for cancer, and 17 percent for diabetes.
"The leading causes of death examined in this study – except unintentional injuries – all are chronic conditions," said lead study author Jiemin Ma, director of the surveillance and health services research program at the American Cancer Society.
"Tobacco control, high blood pressure prevention and management, early detection and screening, and improvements in treating heart disease, stroke and some types of cancer have substantially contributed to reductions in death rates," Ma added by email.
Only one of the six leading causes of death – chronic obstructive pulmonary disease – didn't drop. Rates of death from COPD doubled despite a decline in deaths among men near the end of the study period.
To examine long-term trends in mortality, Ma and colleagues analyzed U.S. national vital statistics to determine the total and annual percent change in age-standardized death rates and years of life lost before age 75 for all causes combined and for the leading causes.
While death rates for five of the six leading causes dropped, the magnitude of the declines recently started to slow for heart disease, stroke and diabetes, the study found.
The progress against heart disease and stroke is due to improvements in controlling high blood pressure and cholesterol, smoking cessation and advances in treatment, the authors conclude.
Reductions in cancer deaths since the early 1990s is also due to tobacco control efforts as well as gains in early detection and treatment, the authors note.
Thursday, October 29, 2015
It sure looked tempting. I'd been meaning to get my flu shot at work, but whenever I had a moment the nurse was busy with patients, and whenever she was available I was locked in mortal combat with the electronic medical record system. The pleasant young woman at the airport clinic offered to check my insurance plan to see if it would be covered, and I was about to pull out my insurance card when the paperwork logistics gave me pause.
Because I'm a doctor and am required to get vaccinated, I'd have to get documentation from the airport kiosk, remember to bring it to my hospital, and figure out how to get it incorporated into my official medical record. And who was this white-coated person anyway, I wondered. Was she a nurse, a pharmacist, an airport employee? Who was certifying this kiosk? Were they storing the vaccine in the proper manner? Did they have equipment available to handle allergic reactions?
When retail health clinics started springing up in the early 2000's, many thought it was a passing fad. But these clinics have exploded over the last 10 years, and now it seems like every other big-box store, supermarket and shopping mall has its own clinic. Apparently airports are now getting in on the action.
Between 2007 and 2009, the number of visits to retail clinics quadrupled. Almost half the visits were after hours — on evenings and weekends when doctors' offices are usually closed. Most were for minor acute conditions like flu symptoms, ear infections and back pain, or for simple preventive care like vaccinations and sports physicals.
Tuesday, October 27, 2015
In 2005, researchers at the University of California, San Diego, began an experiment that would last five years. One by one, they brought 164 study participants to a sleep lab at the U.C. San Diego Medical Center, a room with a sweeping view of the city and the surrounding valley. There, participants underwent polysomnography, the most comprehensive sleep test known to science. A polysomnography machine is an octopus of a medical device: It has scalp sensors to record brain-wave patterns; eye trackers to assess rapid eye movements; breathing sensors that are placed on the nose, mouth, and around the chest; a blood-oxygen sensor for the fingers; and sensors on the legs to track movement. The machine produces a chart—resembling a cross between a musical composition and a seismogram—that traces the brain and body minute by minute through the night.
"I think it's quite beautiful personally," says Lianne Tomfohr, who was the lead author on the study and is now a psychology professor at the University of Calgary. "We can put [sensors] on their head and, through the electricity in their brains, see how deeply they are sleeping. It's a little bit mystical to me that it is even possible."
The San Diego researchers planned to use the polysomnography machine to document slow-wave sleep—the phase of sleep "when it's really hard to wake you up," as Tomfohr describes it. Slow-wave sleep is thought to be the most restorative period of sleep, and it's important to good health: Experiments where people are denied slow-wave sleep on purpose have shown that bodies quickly change for the worse. (One paper, published in the Proceedings of the National Academy of Sciences in 2007, found that study participants who were denied slow-wave sleep for three nights—researchers would sound an alarm in their ears when they entered this sleep phase—became less sensitive to insulin, a precursor to diabetes.)
But it wasn't just slow-wave sleep in general that interested the researchers; they specifically hoped to compare how blacks and whites experienced slow-wave sleep. And what they found was disturbing. Generally, people are thought to spend 20 percent of their night in slow-wave sleep, and the study's white participants hit this mark. Black participants, however, spent only about 15 percent of the night in slow-wave sleep.
So when a group of researchers asked which of these diseases involved the greatest health care costs in the last five years of life, the answer they found might seem surprising. The most expensive, by far, was dementia.
The study looked at patients on Medicare. The average total cost of care for a person with dementia over those five years was $287,038. For a patient who died of heart disease it was $175,136. For a cancer patient it was $173,383. Medicare paid almost the same amount for patients with each of those diseases — close to $100,000 — but dementia patients had many more expenses that were not covered.
On average, the out-of-pocket cost for a patient with dementia was $61,522 — more than 80 percent higher than the cost for someone with heart disease or cancer. The reason is that dementia patients need caregivers to watch them, help with basic activities like eating, dressing and bathing, and provide constant supervision to make sure they do not wander off or harm themselves. None of those costs were covered by Medicare.
Monday, October 26, 2015
This shocked people on all sides of the sweetener debate. It has become an article of faith among many that natural sweeteners like honey are better for you than engineered sweeteners like high-fructose corn syrup, especially for people concerned about diabetes.
Not so fast. A more careful reading of this research would note its methods. The study involved only 55 people, and they were followed for only two weeks on each of the three sweeteners. Sure, glucose and insulin levels and measures of insulin resistance were no different for honey, sugar and high fructose corn syrup. But should we really place so much faith in such a small, short-lived trial?
The truth is that research like this is the norm, not the exception. I've written about nutrition quite often here at The Upshot — about weight loss, dietary guidelines, healthy food choices, the role of exercise in weight loss, the potential benefits of coffee — and a fair amount of the time, it's to counter conventional wisdom, for example about milk, red meat or artificial sweeteners. Just a short while ago, I argued that while more recent nutritional guidelines are, perhaps, more evidence-based, they may still be straying from what we can glean from studies. Readers often ask me how myths about nutrition get perpetuated and why it's not possible to do conclusive studies to answer questions about the benefits and harms of what we eat and drink.
Almost everything we "know" is based on small, flawed studies. The conclusions that can be drawn from them are limited, but often oversold by researchers and the news media. This is true not only of the newer work that we see, but also the older research that forms the basis for much of what we already believe to be true. I'm not ignoring blockbuster studies because I don't agree with their findings; I'm usually just underwhelmed by what I can meaningfully conclude from them.