En español | Alzheimer's isn't inevitable. Many experts now believe you can prevent or at least delay dementia — even if you have a genetic predisposition. Reducing Alzheimer's risk factors like obesity, diabetes, smoking and low physical activity by just 25 percent could prevent up to half a million cases of the disease in the United States, according to a recent analysis from the University of California in San Francisco.

Brain Quiz: After age 20, thousands of brain cells die every day. True or False?

Regular exercise can keep your brain young. — Illustration by R. Kikuo Johnson

Here are 10 new ways you can boost your brain health now.

1) Get moving

"If you do only one thing to keep your brain young, exercise," says Art Kramer, professor of psychology and neuroscience at the University of Illinois. Higher exercise levels can reduce dementia risk by 30 to 40 percent compared with low activity levels, and physically active people tend to maintain better cognition and memory than inactive people. "They also have substantially lower rates of different forms of dementia, including Alzheimer's disease," Kramer says.

Working out helps your hippocampus, the region of the brain involved in memory formation. As you age, your hippocampus shrinks, leading to memory loss. Exercise can reverse this process, research suggests.

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How you work up a sweat is up to you, but most experts recommend 150 minutes a week of moderate activity. Even a little bit can help: "In our research as little as 15 minutes of regular exercise three times per week helped maintain the brain," says Eric B. Larson, M.D., executive director of Group Health Research Institute in Seattle.

 2) Pump some iron 

Older women who participated in a yearlong weight-training program at the University of British Columbia at Vancouver did 13 percent better on tests of cognitive function than a group of women who did balance and toning exercises. "Resistance training may increase the levels of growth factors in the brain such as IGF1, which nourish and protect nerve cells," says Teresa Liu-Ambrose, head of the university's Aging, Mobility, and Cognitive Neuroscience Laboratory.

 3) Seek out new skills

Learning spurs the growth of new brain cells. "When you challenge the brain, you increase the number of brain cells and the number of connections between those cells," says Keith L. Black, M.D., chair of neurosurgery at Cedars-Sinai Medical Center in Los Angeles. "But it's not enough to do the things you routinely do — like the daily crossword. You have to learn new things, like sudoku or a new form of bridge."

UCLA researchers using MRI scans found that middle-aged and older adults with little Internet experience could trigger brain centers that control decision-making and complex reasoning after a week of surfing the net. "Engaging the mind can help older brains maintain healthy functioning," says Cynthia R. Green, Ph.D., author of 30 Days to Total Brain Health.

4) Say "Omm"

Chronic stress floods your brain with cortisol, which leads to impaired memory. To better understand if easing tension changes your brain, Harvard researchers studied men and women trained in a technique called mindfulness-based stress reduction (MBSR). This form of meditation — which involves focusing one's attention on sensations, feelings and state of mind — has been shown to reduce harmful stress hormones. After eight weeks, researchers took MRI scans of participants' brains that showed the density of gray matter in the hippocampus increased significantly in the MBSR group, compared with a control group.

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