Mindfulness may have been over-hyped
In late 1971, US Navy veteran Stephen Islas returned from Vietnam, but the war continued to rage in his head. “I came very close to committing suicide when I came home, I was that emotionally and mentally damaged,” Islas remembers. At his college campus in Los Angeles, a friend suggested he check out a meditation class. He was sceptical, but he found that before long “there were moments that started shifting, where I was happy. I would experience these glimpses of calmness.”
Forty-six years later, Islas says that he has never completely freed himself from his post-traumatic stress disorder (PTSD), which was formally diagnosed in 2000 at the Veterans Affairs (VA) West Los Angeles Medical Center. But he’s convinced that meditation has saved his life.
2000年，美国退伍军人事务部（Veterans Affairs, VA)西洛杉矶医学中心正式确诊伊斯拉斯患有创伤后压力症（post-traumatic stress disorder, PTSD)。时至今日，虽说他身心并未全愈，但伊斯拉斯认为冥想疗法已救了他一命。
Various forms of meditation are now routinely offered to veterans with PTSD. It’s also touted as a therapeutic tool to help anyone suffering from conditions and disorders including stress, anxiety, depression, addiction and chronic pain. More broadly, meditation has come into vogue as a way to enhance human performance, finding its way into classrooms, businesses, sports locker rooms and people’s smartphones through Internet apps like Headspace and Calm.
‘Mindfulness’ meditation, a type of meditation that focuses the mind on the present moment, is wildly popular. It has even become a billion-dollar business.
For all its popularity, however, it’s still unclear exactly what mindfulness meditation does to the human brain, how it influences health and to what extent it helps people suffering from physical and mental challenges. Meditation has been practiced for thousands of years, but psychologists and neuroscientists have studied it for only a few decades.
Some studies suggest that meditation can help people relax, manage chronic stress and even reduce reliance on pain medication. Some of the most impressive studies to date involve a treatment called mindfulness-based cognitive therapy, which combines meditation with psychotherapy to help patients deal with thoughts that lead to depression.
Randomised controlled trials have shown that the approach significantly reduces the risk of depression relapse in individuals who have previously had three or more major depressive episodes.
But many other studies on the effects of meditation have used only small numbers of subjects, lacked follow-up and generally been less scientifically rigorous than other medical studies – clinical trials for new drugs, for example.
A 2017 article that assessed evidence on meditation as a treatment for PTSD summed up the overall state of affairs: “This line of research is in its relative infancy.”
While questions about the clinical outcomes of meditation persist, other studies have focused on a more fundamental issue: does meditation physically change the brain? It’s a tough question to answer, but as brain imaging techniques have advanced and meditation interventions have grown more popular, scientists have begun to take a systematic look at what’s going on.
Meditation that requires one to sit still and focus on the mere act of breathing can encourage mindfulness, says psychologist David Creswell, who directs the Health and Human Performance Laboratory at Carnegie Mellon University in Pittsburgh.
担任美国匹兹堡卡耐基梅隆大学（Carnegie Mellon University）人类健康及行为实验室（the Health and Human Performance Laboratory）主任的心理学家克雷斯韦尔（David Creswell）介绍说，冥想时人要静坐，并且只关注自己呼吸，这样才能够保持正念状态。
But most people spend most or all of their day being anything but mindful. They skip from one thought to another. They daydream. They ruminate about the past, and they worry about the future. They self-analyse and self-criticise.
In a 2010 study, Harvard researchers asked 2,250 adults about their thoughts and actions at moments throughout their day via an iPhone app. People’s minds wandered 47% of the time and mind wandering often triggered unhappiness, the scientists reported in Science.
“In contrast, the capacity to be mindful is associated with higher well-being in daily life,” Creswell wrote in the 2017 Annual Review of Psychology. He cites a 2003 study showing a correlation between mindfulness and a number of indicators of well-being.
克雷斯韦尔2017年在《心理学年度评论》（Annual Review of Psychology）期刊中写道，"而拥有正念意味着在日常生活中有更高的幸福感。"他在文章中也引述了2003年的一项研究结论，指出正念与一些幸福感指标具有相关性。
When people who meditate say they are paying attention to the present moment, they may be focused on their breathing, but maybe also on an emotion that surfaces and then passes, a mental image, inner chatter or a sensation in the body. “Adopting an attitude of openness and acceptance toward one’s experience is critical” to becoming more mindful, Creswell says. The idea is to be view these moments with a detached and non-judgmental curiosity.
Creswell first became interested in mindfulness meditation when he took courses on psychology and Buddhism in high school. Later, in graduate school, he began studying meditation in connection with reducing stress and improving overall health.
“As a scientist, I’m never convinced. I’ve been trained to be sceptical,” Creswell says. “Nonetheless, I do think that there were a number of experiences I had while on meditation retreats that really struck me as very foundational.”
Even the simple but challenging act of sitting still for an hour while meditating made a great impact on Creswell. “Having this disconnect between my body feeling in pain but my mind being completely silent and open… these were very powerful insights for me about how a [meditation] practice could really change people’s lives, or fundamentally change how they relate to suffering in their lives,” he says. “There wasn’t a bolt-of-lightning moment for me, but a lot of these moments of insight in my own retreat experiences that suggested to me that it was worth spending time and effort to do the science.”
People from different religious, cultural and philosophical backgrounds have expounded the benefits of meditation for millennia. Meditation is perhaps most commonly associated with Buddhism, which views it as an instrument for achieving spiritual fulfilment and peace. Creswell calls the act of meditation “a basic feature of being human.”
But the scientific evidence for its benefits is still lacking.
“There is a common misperception in public and government domains that compelling clinical evidence exists for the broad and strong efficacy of mindfulness as a therapeutic intervention,” a group of 15 scholars wrote in a recent article entitled Mind the Hype. The reality is that mindfulness-based therapies have shown “a mixture of only moderate, low or no efficacy, depending on the disorder being treated,” the scholars wrote, citing a 2014 meta-analysis commissioned by the US Agency for Healthcare Research and Quality.
近期，十五位学者共同发布了一篇心理学学术文章，名为《被炒作的正念》（Mind the Hype）。文中有这样一段写道，"公众及政府领域对冥想有一种普遍的误解：他们认为正念作为一种治疗干预手段具有普适性及良好疗效，且这一结论具备强有力的临床依据支撑。"但事实却并非如此。文章引述2014年美国医疗保健研究与质量管理署（US Agency for Healthcare Research and Quality）主持下的一项研究分析结果指出，基于正念作为治疗干预手段的研究表明，"该疗法对于精神疾病及心理障碍的治疗只有轻度和极少的效果，甚至毫无效果。"
Much more research is needed before scientists can say what mental and physical disorders, in which individuals, can be effectively treated with mindfulness meditation, they concluded.
Alongside clinical work, neuroscientists have wanted to know how, if at all, meditation might change what actually happens inside the brain. Does meditation make certain regions more active than others, or more robustly connect one region to another? Does meditation result in new neurons, actually changing brain structure? Some studies suggest the answer is yes.
Neuroscientists have studied the physical effects of mindfulness meditation using functional magnetic resonance imaging (fMRI) and other techniques for the last two decades. Progress has followed on the growing recognition that the human brain is capable of physical changes throughout adulthood, even into old age – forming new connections and growing new neurons when someone learns a new skill, challenges themselves mentally or even just exercises. The emerging view of a brain that can be continually shaped through experience, dubbed neuroplasticity, replaced the long-held idea that after the first few decades of life, the brain’s physiological trajectory was basically one of decline. A number of brain studies suggest that mindfulness meditation may spark neuroplastic renovations in the brain’s function and structure.
Looking under the hood with fMRI, scientists have found that mindfulness meditation activates a network of brain regions that includes the insula (associated with compassion, empathy and self-awareness), the putamen (learning) and portions of the anterior cingulate cortex (regulating blood pressure, heart rate and other autonomic functions) and the prefrontal cortex (the hub of higher-order thinking skills such as planning, decision-making and moderating social behaviour).
科学家使用功能性磁振造影观察人脑时发现，正念冥想会激活人脑中一些区域的神经元连接。这些区域包括负责同情、同理心与自我察觉的岛叶（insula）区域；负责学习与认知的核壳（putamen）区域；控制血压、心跳及其他自主功能的前扣带皮层（anterior cingulate cortex）部分区域；负责高阶思维能力，如规划、决策及规范社交行为的前额叶皮质（prefrontal cortex）等。
It’s uncertain, however, whether these changes in brain activity can be sustained when the individual is not actively meditating, and if so how much people need to meditate for that to happen.
When it comes to actual structural changes in the brain, some studies suggest that mindfulness meditation may increase grey matter density in the hippocampus, a brain region essential to memory. Researchers including Britta Hölzel, now at the Technical University of Munich, and Sara Lazar of Massachusetts General Hospital found evidence for this in a 2011 study.
说到冥想会引发大脑结构实质上的变化，一些研究认为，冥想可能导致海马体中的灰质细胞密度增加。海马体是人脑中负责记忆的区域。一些科学研究者，其中包括慕尼黑工业大学（Technical University of Munich）的霍尔泽尔（Britta Hölzel）及美国麻省总医院（Massachusetts General Hospital）的拉扎尔（Sara Lazar），他们在2011年一项研究中的发现，支持上述说法。
Though intriguing, these studies are nowhere near the end goal. “We need to understand the benefits that the changes in the brain have on behaviour and well-being,” Hölzel says. “‘Changing the brain’ sounds very impressive, but we don’t understand what it actually means.”
Lazar agrees. “Most of the data has only looked at changes over the course of two months of [meditation] practice… Most people feel that [meditation] continues to change and get deeper with extended practice. So we need to conduct studies that follow people for much longer time points.”
Based on their studies of people engaged in meditation, Creswell and his colleagues have proposed that mindfulness acts as a buffer specifically against stress. It does this by increasing activity in regions of the prefrontal cortex that are important for “top-down stress regulation”, while reducing activity and functional connectivity in regions associated with the brain’s fight-or-flight stress response – in particular the amygdala.
基于参与冥想的对象相关研究，克雷斯韦尔与他的同事认为正念能够有效缓解压力，其作用机制是能够激活大脑中负责"自上而下压力调适"（top-down stress regulation）的前额叶皮质，另一方面在负责"战斗或逃跑反应"（fight-or-flight stress response）的应激反应脑区，能缓解其相关活动及功能性神经元连接，尤其是杏仁核部位的连接。
The idea that mindfulness meditation engages parts of the brain involved in top-down stress regulation is widely accepted among researchers, says University of Michigan clinical psychologist Anthony King. But what’s happening in relation to the amygdala is less clear, he says. The amygdala, one of the most primitive parts of the brain, is not just a simple alarm centre associated with responding to threats. It’s central to what’s called the salience network, which is vital for noticing all kinds of important things in one’s environment. In a mother, for example, the amygdala may become very active in response to her baby’s joyful face.
据美国密歇根大学临床心理学家金教授（Anthony King）介绍，正念冥想对于大脑"自上而下的压力调适机制"有积极作用，这一点已被学术界广为认可。但它对于杏仁核区域相关的应激反应是如何作用的却尚不清楚。杏仁核，是人脑中最为原始的部分，它并不仅仅是一个应对外界刺激与危险的应激反应中心，它也是突显网络（salience network）的关键组成部分，对于观察与判断周围环境中一切重要事物非常重要。例如，一位母亲在看到自己宝宝的笑脸时，杏仁核区域会十分活跃。
Mindfulness meditation “helps people have what the old school psychotherapists call ‘reflective capacity,’” King says. “Instead of automatically responding in certain ways, it allows people to have more nuance in their ability to respond to any type of situation – stressful, fearful or otherwise – and create some psychological distance.”
Two studies by Creswell and his colleagues, one in 2015 and the other in 2016, offer some initial findings that seem to support their view of mindfulness meditation as a buffer against stress. Both studies focused on the physiological effects of mindfulness mediation training on small groups of unemployed adults experiencing stress.
In the 2015 study, the researchers found that three days of intensive mindfulness meditation training reduced functional connectivity between the right amygdala, associated with the fight-or-flight stress response, and the subgenual anterior cingulate cortex, which plays a role in modulating emotions.
In the 2016 study, the researchers found that three days of intensive mindfulness meditation training led to increased connectivity between the default mode network, a network of regions engaged when the brain is at rest, and parts of the prefrontal cortex involved in regulating stress. The study also found that meditation led to reduced levels of interleukin-6, a biomarker in the blood for systemic inflammation that’s elevated in high-stress populations.
而在2016年的研究中，研究人员则发现这种连续三天高强度的"正念"冥想增强了大脑"默认网络"（default mode network）与负责压力调适的前额叶皮质区域之间的连接。人类大脑中的"默认网络"是在大脑处于静息状态时而转为活跃的一种大脑工作系统。研究还发现，冥想会显著降低血液中的白细胞介素-6（interleukin-6）的水平。这种细胞因子能够刺激参与免疫反应的细胞增殖。压力较大的人白介素-6的水平一般较高。
King and his colleagues showed similarly promising results in 23 combat veterans of Afghanistan and Iraq with post-traumatic stress disorder in 2016. Brain scans before and after mindfulness-based group therapy revealed an increase in resting-state connectivity between a network in the brain that allows people to control their attention and other parts of the brain involved in rumination and spontaneous thought. This particular connectivity has been seen in healthy people, as well as people who have meditated for long periods, says King.
“What’s important about our study… is that people with PTSD can also have this change in brain connectivity patterns when they do mindfulness practice,” King says. The more this connectivity increases as a result of mindfulness training, “the more their symptoms improve,” he adds, summarising a key finding of the study.
Studies of other conditions suggest similar improvements, although many involve small numbers of subjects and other limitations that make them far from conclusive.
Nevertheless, mindfulness meditation may alleviate symptoms of general anxiety disorder by increasing connectivity between the amygdala and the prefrontal cortex, thereby increasing a patient’s ability to regulate emotions. Meditation may also lessen the perception of pain by reducing pain-related activation of the somatosensory cortex and increasing activation of areas involved in the cognitive regulation of pain.
Fundamentally, mindfulness is an elusive quality to study. It’s an internally generated experience, not a drug that scientists can give to a patient. That creates a question when comparing mindfulness between individuals and especially between distinct studies.
What’s more, there is no universally accepted definition of mindfulness or agreement among researchers on the details of what it entails, Lazar and her colleagues note in the Perspectives on Psychological Science article.
再者，正如拉扎尔等研究人员发布在《心理学视角》（Perspectives on Psychological Science）期刊文章的注释中写道的那样，目前正念冥想还没有举世公认的定义，学界也未对正念冥想所涉及的细节达成一致的结论。
In the context of PTSD, King says it’s likely that mindfulness meditation will continue to supplement more conventional psychiatric treatments. “I would never recommend for people to go to a mindfulness class at the YMCA or the local health centre and think that that’s going to be the same as psychotherapy, because it is not. It really is not,” King says.
But “I think mindfulness is a useful technique in the context of therapy with somebody who’s trained in PTSD treatment.”
But people like Islas who have faced serious mental illness, and others who use mindfulness meditation to ease daily stress, say they’re convinced the practice improves their lives. One day, scientists hope to be able to link that experience to what’s physically happening in the meditating mind.