Dear Doctor: My husband, who plays in a weekend soccer league, is troubled by some new reports he has read that suggest that soccer might be as dangerous as football. Can you explain the studies?

Dear Reader: Your husband may be referring to a pair of studies published in February that examined the potential risks of heading the ball, a common move in soccer. One study, conducted at a British university, found signs of brain damage in a group of professional soccer players, all of whom had decades-long careers. The other study, published by researchers at Albert Einstein College of Medicine in New York, focused on amateur players. The study found an increased risk of concussion both from heading the ball and from accidental contact during a game.

But before you insist that your husband turns in his cleats, let's take a closer look at the data.

The British study examined 14 retired soccer players with dementia. The men, skilled at heading the ball, played for an average of 26 years each. When the brain tissue of six of the players was examined after their death, researchers found signs of trauma.

In four of the six brains, this included chronic traumatic encephalopathy (CTE), a progressive degenerative disease also found in professional boxers, football players and hockey players. Although the small sample size of the British study kept researchers from drawing conclusions, they agreed the results reveal the need for large-scale studies.

In the American study, researchers followed 222 amateur soccer players, both men and women. Players reported how often they headed the ball, as well as any accidental blows to the head during play. They also rated the severity of symptoms like headache, dizziness, altered vision, weakness or confusion, which can indicate concussion.

The researchers concluded that while heading the ball increased a player's risk of concussive impact, accidental contact, like an elbow to the head or colliding with another player, was even more common.

Research into sports-related concussions has previously focused on football and hockey, where bruising impacts are part of the game. Now, scientists are expanding their inquiries into soccer.

Soccer is the world's most popular team sport. It is estimated that amateur players head the ball up to 12 times per game. Add in practice drills, and this can add up to 2,000 headers over 20 years. The question now is whether the effect of all those headers on the delicate structures of the brain can be cumulative.

For the authors of the American study, the answer was yes. They recommend that players be aware of any concussion symptoms, even absent a conclusive concussion diagnosis. Should symptoms appear, players must avoid another collision in the following weeks, when the risk of another concussion spikes significantly.

The truth is, all physical activity carries both risks and benefits. One thing we discuss with our patients regarding soccer is the risk of knee injury, given the high lateral impact forces.

It sounds as though your husband is staying abreast of the latest research, which is wise. He can use it to decide how -- and even whether -- he decides to play soccer in the future.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: A recent study found that air pollution increases the risk of Type 2 diabetes. How can that be? Air pollution can't possibly raise blood sugar levels.

Dear Reader: I can understand your disbelief. My first thought when I saw this study was that it was correlative, not causative. In other words, air quality is simply worse in cities, which are more likely to have large numbers of people with lower socioeconomic status, who, in turn, tend to have greater rates of obesity and diabetes. Then I looked more closely.

Air pollutants assessed in the studies include nitrogen dioxide and particulate matter between 0.1 to 2.5 microns in size (PM 2.5). Early epidemiologic studies showed a correlation between areas of greater pollution and diabetes, but did not control for socioeconomic status. Then came a 2010 study that used census data from three counties in the United States, and assessed both rates of diabetes and Environmental Protection Agency data regarding PM 2.5 pollution.

The authors took into account such socioeconomic variables as median income, high school completion, male sex and ethnicity -- all markers for diabetes risk. The authors found a 16 to 20 percent increase in the prevalence of diabetes in the areas that had the highest amounts of PM 2.5 versus those areas with the lowest amounts, even with all other factors being equal.

Then came this year's study published in the journal Diabetes that included 314 obese Latino children in Los Angeles. The authors analyzed where the children lived; the amount of pollution to which they were exposed, measured by both nitrogen dioxide and PM 2.5; and their parents' socioeconomic data. The children were followed for 3.4 years, during which time they underwent tests of blood sugar, two-hour glucose tolerance, insulin and insulin response to glucose. The authors found that the markers for future diabetes were much greater in those exposed to greater amounts of pollutants. This was independent of socioeconomic status, and even independent of the level of obesity.

The cause isn't completely clear yet. Studies in rodents exposed to pollutants have shown increased inflammation within fat cells, accumulation of cholesterol in the liver and decreased ability of muscles to use sugar. This leads to both metabolic dysfunction and obesity. Further, pollutants can lead to systemic inflammation that in turn leads to insulin resistance, and thus the inability to bring sugar into the cells of the body, leaving it to sit in the bloodstream.

What is clear is that there does appear to be an association between pollution and diabetes, but more studies are needed to evaluate the degree of the association. Regardless, pollution is obviously unhealthy and needs to be controlled within society. The measurements of pollution provided in these studies come from the Environmental Protection Agency, whose existence is to safeguard the health of current and future societies.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I played a pretty rough game of tennis a few weeks ago and developed an ache in my right elbow that turned out to be bursitis. What can I do to ease the pain?

Dear Reader: Our skeletons are marvels of mechanical engineering. They create a scaffold for our muscles, skin and circulatory system, shelter our inner organs, and provide the leverage that makes it possible for us to move about. Wherever our bones meet, particularly in our joints, tiny fluid-filled sacs known as bursa act as cushions. They allow bones and connective tissue to glide easily over one another with minimal friction.

When injury, repetitive movement or sustained pressure causes one or more bursa to become inflamed, the resulting pain and tenderness are characteristic of a condition known as bursitis. Age can play a role in bursitis, as can rheumatoid arthritis. The pain arises when an injured bursa fills with excess fluid and then presses against surrounding tissues and nerves.

The most common locations for bursitis are the hip, knee, shoulder and, as you have discovered, the elbow. The condition is diagnosed via a physical examination of the area, and tests such as an X-ray or an MRI. When a physician suspects that infection may play a role in bursitis, she or he will take some fluid from the affected area for testing.

Since we're not sure what treatment you may have already received, we'll run down our approach with our patients. We begin by addressing the underlying cause, which is inflammation. Rest is important. Bursitis can be brought on by a specific activity, such as tennis for bursitis in the elbow, or throwing a ball or lifting a toddler for bursitis in the shoulder. We recommend that our patients refrain from the particular action until the condition has cleared up.

Anti-inflammatory medications such as aspirin and ibuprofen will help alleviate swelling and pain. If necessary, more powerful anti-inflammatories are available by prescription. Ice compresses applied for 15 to 20 minutes every four to six hours, for three to five days, can also be quite effective in managing the swelling and pain.

Less frequently, it becomes necessary to drain the excess fluid from the bursa with a needle and syringe, a procedure known as aspiration. If we suspect infection rather than injury plays a role, we will send the fluid out for analysis.

In many cases, bursitis will resolve itself over the course of a few weeks or, perhaps, months. In some instances, though, the pain may be persistent. When patients don't get relief from rest, icing and anti-inflammatories, the next step can be a cortisone injection into the site. Cortisone usually provides speedy relief from pain and can be targeted to a specific location.

We have found that gradually adding a gentle stretching program and some easy strengthening exercises can aid recovery. An elbow band, which reduces the pressure of the muscles in the forearm, can help with pain. Your family doctor will be able to help you with all of these.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)