Dear Doctor: Could working too much actually give me an irregular heartbeat later in life as a study I heard about suggests? I'm 55 and run my own tech support business, so I keep some really long and often irregular hours.

Dear Reader: The image of the "Type A" person who devotes long hours to the job has long been cemented into the national lexicon. The fact that this driven, goal-oriented temperament is considered admirable, if not an outright attribute, says a lot about us as a nation of workers. But the results of a recent study remind us that this kind of single-mindedness can come at a price.

Previous research has connected long working hours to an increased risk of having a stroke or developing coronary artery disease. Now, according to a paper published in the European Heart Journal last summer, people who work 55 hours or more per week also have a greater chance of experiencing atrial fibrillation as the years go on. This irregular heartbeat, which feels fluttery and is often quite rapid, means the electrical signals that prompt the heart have gone haywire. Rather than a controlled rhythm and sequence that allows the upper chambers of the heart to move blood as efficiently as possible, AFib is an ineffectual spasm that is associated with a rise in the risk of heart-related complications and stroke.

In this study, researchers looked at health data from about 85,500 working women and men from Finland, Denmark, Sweden and the United Kingdom. None of the study participants had a history of atrial fibrillation. As each participant entered the study, the number of hours that they worked per week was noted. At the end of about 10 years, each study participant was evaluated again. Using data collected from electrocardiograms, hospital and pharmacy records, as well as death certificates, researchers found 1,061 new cases of atrial fibrillation. For the group as a whole, this translated to 12.4 new cases of AFib per 1,000 people. However, when researchers looked at study participants who spent long hours at work, the incident rate rose to 17.6 new cases of AFib per 1,000 people. That's an increased risk of 40 percent, according to the statistical analysis in the study.

Studies like this, which identify outcomes based on analysis of selected behaviors, point out a correlation. They do not suggest that the behavior is the cause. In the case of the participants who spent 55-plus hours working, lifestyle issues may have also played a role in their health outcomes. Not only did people who worked a lot report more depression and anxiety at the start of the study, they were more likely to be overweight, spend less time in leisurely pursuits, and reported more tobacco and alcohol use.

If your own work habits give you cause for concern, step back and see what you can change. You may not be able to cut your hours, but adding meditation and deep breathing into your daily routine can help with stress. Having a better diet, cutting out tobacco and adding regular exercise will also add to your overall quality of life.

(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 heard that for senior citizens, being overweight and losing muscle can be bad for your memory. Is this really true? I'm worried because my husband has pretty much taken a seat on the couch since he retired two years ago. He hasn't gained any weight, but our sons have been saying that he's lost a step or two mentally. What can we do?

Dear Reader: The potential link between body fat, muscle mass and cognitive function in older adults has been a topic of discussion for many years. Dementia is a major cause of disability among the elderly, so it's an important area of study. In 2010, 30 million elderly adults worldwide had some type of dementia. That number is expected to more than triple to 106 million by 2050. Since cognitive decline is among the first observable symptoms of most types of dementia, detecting risk factors and identifying interventions is important to public health.

So far, studies into the connection between body fat, muscle mass and cognition in elderly adults have come up with conflicting results. The only hard-and-fast conclusion so far has been that the issue is complex and deserving of more study. Now we have the latest entry into the discussion, published in the journal Clinical Interventions in Aging earlier this year. A study found that the progressive loss of muscle mass among the elderly, as well as obesity, may be risk factors for cognitive decline that leads to dementia. This was found to be true when the conditions happened independently of one another but was more pronounced when they occurred together.

The progressive loss of muscle mass that takes place as we age is known as sarcopenia. And though it's associated with older adults, the process actually begins in our early 30s. Estimates put that loss at 3 to 5 percent of total muscle mass per decade. Combine this progressive loss of lean muscle mass with an increase in weight and body fat percentage and it's a condition known as sarcopenic obesity. (Sometimes it's referred to as "skinny fat.") Because muscle weighs more than fat, as muscle mass ebbs and fat percentages increase, the shift in body composition doesn't show up on the scale. Someone's weight can remain the same, but the ratio of lean muscle mass to total body fat can signal obesity.

In this most recent study, scientists analyzed the health data, including results of strength and cognitive testing, of 353 men and women with an average age of 69. It turned out that those with sarcopenic obesity fared the worst in cognitive testing. Those with just sarcopenia or just obesity fared only slightly better. Bottom line -- whether alone or together, loss of muscle mass and obesity were linked with impaired cognitive function. The reasons why aren't known, though inflammation and its attendant ills are high on the list of suspects.

As for your husband, persuading him to swap some couch time for weight-bearing and aerobic exercises is a good start. It will improve muscle strength, promote joint health and give his metabolism a boost. And if his mental lapses are apparent to the entire family, it's probably wise to have some cognitive testing done as well.

(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: It's a real nightmare trying to pry our two grandsons away from their online video games when they are visiting. There's always a fight followed by hours of sulking and crankiness. Our son and his wife say it's easier to just let the kids play. Could they be addicted?

Dear Reader: Anyone who has ever interacted with a digital screen, be it a smartphone, tablet or computer, knows all too well the lure -- and allure -- of electronic devices. They draw you in, engage your brain at a startlingly deep level, and time and awareness just vanish. Up the ante with the dynamic visuals and mesmerizing world of a video game, and non-gamers often find themselves in a losing battle for the time and attention of their loved ones.

When it comes to the question of addiction, no less an authority than the World Health Organization has recently added "gaming disorder" as a new mental health condition to the 11th edition of its International Classification of Diseases, or ICD. However, the bar for someone to earn this new -- and somewhat controversial -- diagnosis is quite high. According to the ICD, gaming disorder is "a pattern of gaming behavior ('digital-gaming' or 'video-gaming') characterized by impaired control over gaming, increasing priority given to gaming over other activities to the extent that gaming takes precedence over other interests and daily activities, and continuation or escalation of gaming despite the occurrence of negative consequences."

Not only that, the digital devotion must be so powerful that it severely impairs all interactions, including with family and friends, at work or school, and in areas of self-care. Finally, the behavior must take place for at least one year before an official diagnosis is possible.

With that definition in mind, it's unlikely that your grandkids qualify as addicted. But that doesn't make the situation you describe any less challenging. The boys are choosing a world visible and meaningful only to themselves over the cooperative dynamics of family life. Lost in the flow of the game, their universe is a potent mix of questions, answers, penalties, risks and rewards. And with the way these games are engineered, particularly the role-playing games, there is no logical place to stop -- or even pause.

On the plus side, immersive games can expand the imagination, foster collaboration and sharpen cognitive skills. But when kids are parked in front of a screen, they're missing out on activities, experiences and events that will help them become healthy and productive adults. In your case, the challenge seems to be that the parents don't see enough of a problem to intervene. However, when the boys are visiting your home, you can make a point of engaging them in the analog world.

Give them a set time for gaming and be firm when that time limit is up. Then be prepared with something interesting for them to do. Think of activities with distinct start and finish times, and with concrete end products or the potential for rewards. Show them that even in the real world, they can achieve the video gaming world's enthralling sense of flow.

(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.)