Dear Doctor: Just how effective is exercise against depression? I read that stopping exercise worsens depression in as little as three days, so that seems pretty powerful.

Dear Reader: After decades of research into the subject, it's safe to say there's a clear connection between exercise and a sense of well-being. Studies have shown that regular exercise improves mood and can have a positive effect on symptoms of depression. Considering that up to 10 percent of people in the United States are now dealing with depression, the mental health benefits of exercise are very good news. Now, findings from researchers at the University of Adelaide in Australia support what many part-time exercisers may have already intuited -- that when you stop being active, those mental health benefits fade away.

The scientists noted that while numerous studies have looked into the positive effects of an ongoing exercise program, there was a lack of information about what happens when people stop exercising. To fill in that gap, they reviewed existing data from nine studies in which a total of 152 adults with symptoms of depression first undertook and then ceased an ongoing exercise program. Though the specifics of the activities varied, participants had been exercising for at least 30 minutes three times per week, for a period of three months.

When they crunched the data, the authors found that in some participants, depressive symptoms reappeared in as little as three days after stopping their exercise regimens. Other participants reported a return of symptoms after one and two weeks. In all of the studies, the effect was more pronounced among the female participants than in the men. As with all studies that examine existing data, cause-and-effect conclusions can't be made. But the apparent connection between the cessation of exercise and a fairly quick return of symptoms of depression is worth further study.

As for exercise itself, any increase over a sedentary lifestyle can yield positive results. When researchers followed 22,500 people in Norway over the course of nine to 12 years, they found that those who had engaged in regular exercise, some of them for as little as one hour per week, had a reduced risk of developing symptoms of depression. Even more surprising, it didn't matter how intense that activity was. Although a one-hour walk in the park wouldn't deliver the endorphin high of a brisk run, it still yielded mental health benefits. Whether it was the social aspect of being among people, the self-discipline required to get up and out of the house, or the sense of structure conferred by a regular routine, researchers found it added up to an improved sense of well-being.

The takeaway here is to do something, and to do it regularly. We think that you'll have the best shot at success if you do something you truly enjoy. Believe it or not, there are studies that highlight the mental health (and physical) benefits of jumping on a trampoline. Resistance training -- that's weight lifting -- has been shown to improve mood as well as muscle tone. Perhaps yoga or tai chi, Pilates or dance classes are more to your taste. The important thing is to get started.

(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: What is your opinion of using Cialis to treat benign prostatic hyperplasia? And what should the dosage be?

Dear Reader: Cialis (tadalafil) may be most familiar as an effective drug for erectile dysfunction, similar to other drugs in its class, such as Viagra and Levitra. Because its chemical structure is different, however, it lasts longer in the bloodstream. In simple terms, tadalafil works by inhibiting a specific enzyme, PDE5, and in doing so increases blood flow.

Epidemiologic studies have noted an association between erectile dysfunction and the lower urinary tract symptoms of benign prostatic hyperplasia (BPH), also known as an enlarged prostate. Those symptoms include urinary frequency, urgency, hesitancy and poor stream. Accordingly, PDE5 inhibitors have the potential to help treat not only erectile dysfunction but also BPH.

As for studies assessing the use of Cialis, Viagra and Levitra for BPH, the results have been fairly promising. A 2011 analysis of 11 studies looked at the benefits of PDE5 inhibitors compared with a placebo. Six of the studies used Cialis, four used Viagra and one used Levitra. Participants filled out a questionnaire prior to starting the studies, which lasted eight to 12 weeks, and again at the end. The trials found that the reported symptoms of BPH improved with each of the medications compared to placebo. However, none of the five studies actually assessing urine flow found an improvement with the PDE5 inhibitors, and four failed to show an improvement in the emptying of the bladder.

Later studies, with the use of Cialis specifically, also verified a reduction in urinary symptoms. The greatest benefit came from the use of 5 milligrams of Cialis on a daily basis, with 60 to 79 percent of participants reporting an improvement of symptoms, and more than 50 percent noting an improvement after one week.

A 2012 study in the journal European Urology compared Cialis with the most commonly used drug for BPH, Flomax: 171 patients took Cialis and 167 patients took Flomax. Researchers found significant and near equal improvement of most urinary symptoms. But Cialis didn't improve urine flow, as did Flomax and other alpha-1 blockers. That said, Flomax does not benefit erections.

It might be tempting to combine an alpha-1 blocker like Flomax with Cialis, but the two medications together have the potential to severely lower blood pressure. That's not to say they will, however. A recent 2017 study, which assessed that specific combination, did not show any significant adverse effects. Clearly, more studies are needed to know if the combination is safe and any better than Flomax alone.

If you have erectile dysfunction and symptoms of enlarged prostate, Cialis can benefit both of those problems. A daily dose of 5 milligrams should be effective, with about 70 percent of people seeing improvement of urinary symptoms at four weeks.

Please note that a recent column on the potential link between peripheral neuropathy and MRI with gadolinium contrast was unclear on the use of an iodine contrast agent. The latter is administered with a CT scan, not MRI, and should be used with caution in those with kidney dysfunction.

(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: Can you talk about overweight kids and fatty liver disease? I thought this was something that only happens to alcoholics.

Dear Reader: While excessive alcohol consumption is certainly one path to a diagnosis of fatty liver disease, the condition can affect drinkers and non-drinkers alike -- raising the risk of heart disease and potentially causing subsequent problems that can lead to liver cancer. New research suggests that children who are overweight as toddlers may go on to develop the metabolic markers of fatty liver disease several years later.

Fatty liver disease is pretty much what it sounds like -- a damaging buildup of fat in the tissues of the liver. One path to that buildup is through the heavy use of alcohol, but what we're talking about here is non-alcoholic fatty liver disease, or NAFLD. This occurs when factors other than alcohol cause fat to accumulate in the liver. The presence of the fat triggers an inflammatory response that, over time, leads to liver damage.

The condition is most common among individuals who are obese or overweight, have diabetes or pre-diabetes, have high blood levels of cholesterol or triglycerides, and have high blood pressure. It's associated with metabolic syndrome, and also with certain cancer drugs, corticosteroids and hepatitis C. Research suggests there may be a genetic component as well. And although NAFLD is most common among individuals in their 40s and 50s, emerging data shows that children can be affected.

The liver, which is the largest internal organ, has a daunting to-do list. It converts food into fuel, stores that fuel and makes it available as needed, clears toxins from the blood and renders them harmless, makes proteins that help blood to clot, breaks down fats, helps manage blood sugar levels, and stores and releases various minerals and vitamins. And that's just scratching the surface. Bottom line, the liver's numerous metabolic functions mean that for you to stay healthy, your liver needs to be healthy as well.

In fatty liver disease, the presence of fat causes inflammation, which can lead to scarring and damage to the complex structures of the liver that can be irreversible. At its most extreme, NAFLD can lead to cirrhosis of the liver and even death. It's estimated that 80 million people in the United States -- that's one-quarter of the U.S. population -- have some degree of fatty liver disease. Close to 60 percent of them are men.

While NAFLD has no obvious symptoms, abdominal pain, chronic fatigue, nausea, loss of appetite and elevated liver enzymes may be indicators of the condition in individuals who exhibit the appropriate risk factors. Although at this time there are no specific treatments for the condition, lifestyle changes can have a beneficial effect.

Reaching and maintaining a healthy weight is considered the leading preventative. Several studies have shown a direct correlation between increased sugar consumption and certain metabolic changes that stress the liver. Soft drinks in particular have been shown to increase the markers of fatty liver disease. So ditch the sweets, sodas and processed foods. Focus instead on fresh fruits and vegetables, leafy greens, healthful fats and lean proteins. Your liver -- and your whole body -- will thank you.

(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.)