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Mindful : April 2018
letters alone. Instead, it slaps on a molecular silencer or a molecular turbo-charger, affecting whether they are able to make the protein they spell out and in what quantities. You’ve almost certainly inherited genes that suppress tumor formation; if they are epigeneti- cally silenced, your anti-cancer defenses are as weak as the starship Enterprise without its deflector shield. You might have inherited a gene that causes schizophrenia; if it is epigenetically silenced, you won’t develop that devastating ill- ness. Epigenetics is a big reason why DNA is not destiny: Just because you have a gene doesn’t mean that gene will be active. Now for those rats. In a breakthrough 2004 paper, scientists led by Michael Meaney of McGill University discovered that how baby rats are treated by mom can, via epigenetic mech- anisms, silence genes involved in the rat pups’ stress response. When a rat mother is inatten- tive to her pups, rarely licking and grooming them, a gene that allows the brain to respond to stress hormones is silenced. That causes produc- tion of stress hormones to spike (to make up for the brain’s unresponsiveness); the rat becomes a neurotic mess, freezing when placed in unfamil- iar surroundings, jumping like a turbo-charged flea when startled, and chronically flooded with stress hormones. Life experiences such as quality of maternal care, Meaney showed, can reach into DNA and affect gene activation via epigenetics. Nurture had trumped nature. That study launched the scientific search for other experiences with epigenetic effects. In 2009 Meaney’s team found that the brains of people who committed suicide and had suffered abuse as children contained significantly more “be silent!” switches on the gene involved in the stress response—the same gene that was silenced in rats raised by neglectful moth- ers. Epigenetic silencing seems to impair the stress-response system in people much as it does in rat pups, making it hard to cope with setbacks and adversity, thus raising the risk of suicide. As we go through life, we accumulate epigen- etic changes. Both random chance and expe- riences—with parents, friends, life itself—can reach into our very DNA, silencing some genes and amping up others. Remarkably, the longer identical twins have lived together (presumably sharing more experiences), the more similar they are epigenetically. That raises an obvious question: If the life that just happens to us exerts epigenetic effects, can activities we choose also exert such effects? There is no shortage of research suggesting such “mind over gene” effects. For instance: A 2011 study found that 30 experienced med- itators in the three-month “Shamatha Project” meditation retreat had, by its end, significantly greater activity of an enzyme called telomerase, which keeps the protective tips of chromosomes, called telomeres, intact. (Cells with shortened telomeres, according to a prevailing but not unquestioned theory, age faster.) Greater telo- merase activity might reflect epigenetic changes that increase the activity of the telomerase gene. A 2012 study of long-term meditators found different patterns of DNA activation, possibly reflecting epigenetic effects, during periods of self-reported “higher states of consciousness” compared to ordinary awareness. A 2014 study led by Richard Davidson of the University of Wisconsin, Madison, found lower expression of genes involved in inflammation and of molecules that activate genes (an epigen- etic effect) in 19 experienced meditators after a day of intensive meditation, but not in a control group of 21 non-meditators. Such epigenetic reg- ulation of genes involved in inflammation “may represent some of the mechanisms underlying the therapeutic potential of mindfulness-based inter ventions,” the researchers concluded. Fifteen experiments that measured epigene- tic changes after mind-body therapies such as tai chi and MBSR reported that genes involved in inflammation (particularly those in what’s called the nuclear factor kappa beta, or NF-kB, pathway) were turned down after the therapy, a 2014 review found. That should cause lower levels of chronic inflammation, whose health consequences range from cancer to Alzheimer’s disease. Reduced gene expression is an epigen- etic phenomenon (though it can result from non-epigenetic effects, too). A 2017 review of 18 such studies also found support for the idea that mind–body interventions turn down NF-kB. In The Telomere Effect, a New York Times bestseller from early 2017, psychologist Elissa Epel—who has researched how mindfulness and other self-regulation programs could affect cellular aging—teamed up with Nobel prize-winning BOOKSHELF | Habits and Aging physiologist Elizabeth Black- burn. Together they pro- duced a review of the science surrounding how life habits may lengthen telomeres (the structure at the tip of a chro- mosome), which are thought to affect the aging process. IF THE LIFE THAT JUST HAPPENS TO US EXERTS EPIGENETIC EFFECTS, CAN ACTIVITIES WE CHOOSE ALSO EXERT SUCH EFFECTS? 38 mindful April 2018 brain science