Mindfulness meditation has been practiced by Buddhists for thousands of years. But today, in our electronic, distraction-filled world, the ancient practice seems to be having an unlikely moment of trendiness — so much so that it's the focus of a new app that recently garnered a New Yorker profile.

The app, called Headspace, claims that by emphasizing attention on the present moment, "regular mindfulness practice, through meditation, is an effective treatment for stress, worry, lack of focus, relationship problems, addictions and more."

"Meditation has been shown to cause distinct changes in brain structure"

It's tempting to dismiss all this as a pseudoscientific sales pitch. But we actually have scientific evidence that some of these claims are quite real.

"Mindfulness meditation has been shown to cause distinct changes in brain structure and brain function," says Yi-Yuan Tang, a Texas Tech neuroscientist who studies meditation and recently reviewed the state of the research for the journal Nature. In experiments, he and others have found that regular meditation seems to improve people's focus and emotional control, in particular.

There are plenty of caveats to this research. It's early on, and some of the studies include relatively few people. Many are controlled trials(which track how a period of regular meditation affects people, compared with a comparison group that doesn't meditate), but others involve people who've been meditating for years — so they don't prove that meditation caused the effects, but simply show an association. Moreover, they vary person to person.

"Some people may overstate what meditation can do," Tang says. "But it does have some real benefits."

What is mindfulness meditation?

Mindfulness meditation originated in Buddhist traditions and was first popularized in the West in the 1970s and '80s. In essence, it's any exercise that encourages you to focus on your sensations and thoughts in the present moment. As Henepola Gunaratana puts it in Mindfulness in Simple English, "One’s attention is carefully directed to an intense examination of certain aspects of one’s own existence."

In practice, this can take a huge number of different forms. Most often, people begin meditating by sitting upright for 10 minutes or so and focusing entirely on their breathing. The idea is to concentrate your attention on the many physical sensations that accompany each breath: the flow of air through your nostrils, the expansion of your chest cavity, the movement of your diaphragm.

It's okay if your thoughts wander — at first, they almost certainly will — but it's good to be aware of their wandering. For most people, daily practice makes this sort of meditation come more naturally over time.

Meditation improves your ability to focus even when you're not meditating

Researchers have used a number of different tests to assess how regular meditation affects people's ability to control their attention. One review of 23 different studies found that in general, people who've been meditating for just a few months perform better on tasks that test their ability to shut out distractions, while longer-term meditators show a markedly improved ability to maintain focus for especially long periods of time. Fifteen of these studies were randomized controlled trials, which compared the changes non-meditators underwent after a period of meditation with those of people who never meditated.

Many of these sorts of experiments test meditators' ability to ignore one set of stimuli and focus in on another. The Stroop test, for instance, requires you to report the color a word is written in but ignore the actual word. After a period of regular meditation, people are better at rattling off many colors correctly — and doing other tasks that require shutting out distractions.

Interestingly, meditators also show an improved ability to intentionally split their attention among multiple things. One experiment, for instance, showed participants two photos in extremely rapid succession. After a three-month training period of intense meditation, people showed an improved ability to pick out details from the second photo. A comparison group of non-meditators were much more likely to only notice details from the first. There's also evidence that meditation can improve people's working memory — the ability to retain and recall new information.

All this is especially interesting because typically attention control and working memory decline significantly as we age. But research suggests that long-term meditation can slow down this decline.

Meditation also helps you better control your emotions

Apart from focusing your attention on the present moment, mindfulness meditation preaches accepting and letting go of negative emotions. Practicing this sort of behavior, scientists say, seems to improve meditators' ability to control their emotions even when they're not meditating. It seems to give meditators more emotional ballast, making them less easily swept up in the ups and downs of the present.

In experiments, for instance, meditators are less thrown off by emotionally unpleasant photos (say, showing a car crash or a violent scene) while completing an unrelated task. FMRI-based studies show that after two months of meditation, these sorts of images trigger less activity in the amygdala, the brain region involved in sadness and anxiety. In survey-based studies, people report being less afraid of their emotions and experiencing less anger and stress in their daily lives after a multiweek meditation course, compared with people who didn't take the course.

Consequently, there's some hope that meditation might be a useful tool in treating things like anxiety disorders and addictions. It's very early on, but a few small studies have suggested that it can reduce cravings in long-term smokers and improve the symptoms of people with general anxiety disorder, compared with non-meditators. Still, we need longitudinal studies that track and compare meditators versus non-meditators over time to have a better idea of whether it really works.

Meditators' brains look different from non-meditators'

To learn more about the brain mechanisms underlying these changes, about a decade ago, neuroscientists began using fMRI machines and other brain scanners to look inside the minds of people who'd been regular practitioners of mindfulness meditation for years. When they did, they found that their brains looked noticeably different from non-meditators'.

More than 20 of these sorts of studies have been conducted since. Some of their conclusions have varied, but a recent meta-analysis led by Kieran Fox of the University of British Columbia found that on average, practiced meditators tend to have distinct differences in eight brain areas compared with non-meditators.

The most dramatic difference is an increase in tissue in the anterior cingulate cortex — an area of the brain known to be involved in maintaining attention and controlling impulses. Other studies have found that meditators have thicker tissue in several other regions of the cortex implicated in attention control and body awareness. Extremely long-term meditators (in one study, Buddhist monks), meanwhile, appear to have stronger connections between various brain areas, which could further contribute to focus.

Interestingly, regular meditation has been associated with a reduction in the size of the right amygdala, a region of the brain linked to the processing of negative emotions, especially sadness and anxiety.

These changes reflect a broader fact about the brain: neuroplasticity

Some studies suggest that meditators have reduced activity in the insula — a brain region responsible for the perception of pain — which could explain why they report feeling lower levels of pain when exposed to the same painful stimuli (say, putting their hands in a bucket of ice-cold water) than non-meditators. Results in this area, though, are somewhat mixed.

Although the fine details of how these changes occur are still a mystery, they reflect a broader fact about the brain: a phenomenon called neuroplasticity. In general, the neural circuits that you use most are reinforced and strengthened over time, and those you don't use gradually atrophy.

Still, these brain scanner studies largely compare people who happen to have been already meditating long-term with those who haven't, unlike the experimental studies. That means these studies can't prove that meditation caused these changes: It's possible that people with larger anterior cingulate cortices, for instance, flock to meditation in the first place.

Scientists still have lots of questions about meditation

Despite all these findings, we're still in the very early stages of research into meditation as a whole — and in many areas, scientists still have more questions than answers.

One big question is how much these effects vary person to person, and why. "People respond to mindfulness meditation differently," Tang says. "These differences may derive from experiential, temperamental, personality, or genetic differences." Still, he and others aren't exactly sure.

Can meditation really be a treatment for depression, anxiety, and drug addiction?

The amount of meditation necessary to trigger these sorts of behavioral and neurological changes is also a big question. Some studies look at meditators who've only had a few hours of practice, while others involve lifelong meditators, and we don't have a great sense of when these benefits really start to occur.

Finally, there's the pressing question of how useful mindfulness meditation might be for medicine. Can it really be a treatment for depression, anxiety, and drug addiction — or is this a totally unrealistic dream? And if it works, how exactly should it be prescribed to patients?

"We've found that mindfulness meditation could help with deficits in self-regulation, which is associated with things like addiction and mood disorders," Tang says. "But we need to replicate and expand upon these findings to figure out how it'd work best in treating people."