Dear Doctor: I’ve been on a few different medications for depression, but none of them did much of anything. A friend keeps going on about psychobiotics, which to me doesn’t even sound like a real word. What is he talking about?

Dear Reader: Unfortunately, it’s true that antidepressants don’t work for everyone. This makes treating the estimated 16 million Americans who experience at least one major depressive episode each year an ongoing challenge. A study funded by the National Institutes of Health found that only one-third of individuals diagnosed with depression found complete relief through the first course of medication that they were prescribed.

As has happened with you, people living with depression often try several different medications -- or combinations of medications -- in a trial-and-error search for a treatment that works. Even when antidepressants are successful at relieving symptoms, they come with an array of potential side effects, both physical and emotional. And when an antidepressant does work, it’s possible for the patient to build up a tolerance. As a result, the drug becomes less effective over time.

All of this has caused scientists to keep seeking effective treatments. An important area of research pertains to something called the “gut microbiome.” As scientists learn more about the importance of the trillions of microorganisms living in our bodies, they have established a connection between our guts and our brains.

New research shows that the makeup of the gut microbiome plays a significant role not only in mental health, but in cognition as well. The channel of communication runs both ways -- the gut influences the brain, and the brain influences the gut. One theory is that the vagus nerve, which runs from the brain to the gut, acts as an information highway, with messages traveling in both directions. Some scientists have referred to the gut as our “second brain.”

Out of these findings has come the term “psychobiotics,” the one your friend used. Specifically, it refers to the types of live bacteria, or probiotics, that impart positive mental health benefits. Research in mice has shown that infusions of beneficial bacteria to the gut resulted in markedly lower levels of inflammation in the brain. This, in turn, influenced behavior, including lower levels of anxiety and fear when the mice made their way through a stressful maze.

Scientists are still figuring out how these findings in animal studies translate to humans. Someday antidepressants may consist of doses of feel-good bacteria tailored to the needs of each person’s particular gut microbiome. In the meantime, the goal is to develop and maintain a gut microbiome that’s robust and diverse. This is achieved by eating a high-fiber, low-sugar diet that’s filled with plant-based and fermented foods. Exercise has been shown to be helpful to the gut microbiome, too.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I hate having migraines. The pain is brutal, they knock me down for days and everyone thinks I’m just having a bad headache. Why do they happen? Can you tell me about any new therapies?

Dear Reader: For anyone lucky enough to never have had a migraine, it’s much more than just a bad headache. Migraine is an extended, often debilitating full-body experience. Severe throbbing head pain is typically accompanied by nausea and sometimes vomiting. Other symptoms are extreme sensitivity to light, motion and sound. A migraine can last for several hours or several days.

Many people also have a range of symptoms before an attack. Known as a migraine aura, it’s a cluster of visual, sensory and cognitive disturbances such as flashes of light, prickling sensations on the skin and lapses in speech or reasoning. Migraines often conclude with a phase known as postdrome, sometimes known as a migraine hangover. Postdrome can include nausea, continued sensitivity to external stimuli, body aches, exhaustion and problems concentrating. In addition, studies show that individuals with chronic migraine are at higher risk of anxiety and depression.

Despite having been studied for at least 3,000 years, we still don’t have a definitive answer for what causes migraines in an estimated 3 billion people worldwide. It is known to be a complex neurological disorder, likely with a genetic component. Women are three times more likely to suffer from migraines than men.

Behaviors known as “triggers” can launch a migraine. These include a skipped meal, irregular sleep, changes to caffeine intake and emotional or physical stress. Foods associated with migraine include chocolate, fermented foods, aged cheeses, alcohol in general and red wine in particular. Birth control pills and antidepressants are also believed to have an effect on migraine frequency. Unfortunately over-the-counter pain medications, which can provide relief, can also result in a “rebound” headache.

In the past, migraine patients relied on a variety of medications for relief, the majority of them created to treat other conditions. These include antidepressants, hypertension medicines, Botox injections, opioids and a class of drugs called triptans. Vitamins and supplements such as vitamin B2, magnesium, Coenzyme Q10 and melatonin have proven helpful. And although aerobic exercise is known to reduce the frequency and severity of attacks, people who have regular migraines often feel too poorly to exercise regularly.

Most recently, a new class of drugs known as monoclonal antibodies, the first medications developed specifically for migraine sufferers, are offering hope. The FDA approved three such treatments earlier this year. Delivered via a monthly injection, they have been shown to reduce the number of migraine days in some patients by half. They’re costly and don’t work for everyone, but it’s worth checking with your doctor to see if they might be right for you.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: What’s going on with that outbreak of lung disease that’s hitting people who vape? Our 20-year-old son and a lot of his friends vape sometimes, and we’re getting worried.

Dear Reader: You’re not alone in your concerns. Federal health officials have said that close to 200 cases of a serious lung disease that appears to be associated with vaping have been reported. There now also appears to have been at least one death caused by this illness, an adult male in Illinois, according to officials in the state.

The Centers for Disease Control and Prevention is investigating reports from 22 states to date. Most cases involve males ranging in age from 17 to 38. The U.S. Food and Drug Administration is continuing to investigate a potential link between the use of e-cigarettes and serious neurological symptoms, including seizures, fainting and tremors.

Symptoms of the respiratory illness include pressure or tightness in the chest, shortness of breath and difficulty breathing that becomes progressively worse. Some patients also have experienced fever, weight loss, nausea, fatigue and diarrhea. Imaging tests of the patients’ lungs have all revealed abnormalities, including areas of increased density, known as opacities.

In some cases, patients have required mechanical ventilation to aid in breathing and have improved after treatment with corticosteroids. An 18-year-old man in Florida who vaped went to a hospital emergency room and learned he had a hole in his right lung, which had caused it to collapse. Tests for infectious agents have been largely negative, which has added to the mystery of what is causing the disease. One behavior all patients have had in common is recent vaping.

The challenge is that the similarities end there. The patients had inhaled a variety of products, including cannabis-based products, nicotine and homemade substances. They had used a number of different vaping devices. They had purchased the products in a variety of stores and via several different online retailers. This has led investigators to turn their attention to the delivery system of vaping devices.

E-cigarettes work by using a coil to super-heat a liquid and turn it into an aerosol, which is then inhaled. These super-fine particles can then be drawn deep into the lungs. Vaping liquids contain numerous volatile organic chemicals and other substances, not all of which are identified on the packaging. Some of them are known to be potentially harmful. The flavorings used in vaping liquids also contain numerous compounds whose long-term health effects are unknown.

As federal and state health officials continue to investigate, medical professionals and the public have been asked to report any vaping-related symptoms or illnesses, along with specifics about the products that were used, to state health authorities.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)