In the largest observational study to date on “superagers”—people in their 80s who have brains as sharp as those 30 years younger—researchers in Spain found key differences in lifestyle that may contribute to these older adults’ sharp minds.

Superagers in the study had more gray matter (灰质) in parts of the brain related to movement, and they scored higher on flexibility, balance and mobility (行走能力) tests than typical older adults—even though the physical activity levels of the two groups were the same. “Though superagers report similar activity levels to typical older people, it’s possible they do more physically demanding activities like gardening or stair climbing,” said senior author Bryan Strange, director of the Laboratory for Clinical Neuroscience at the Technical University of Madrid, in a statement.

“From lower blood pressure and obesity levels to increased blood flow to the brain, there are many direct and indirect benefits of being physically active that may contribute to improved cognitive abilities in old age.” The study, published on Thursday in The Lancet Healthy Longevity journal, followed 64 superagers and 55 cognitively normal older adults who were part of the Vallecas Project, a long-term research project on Alzheimer’s in Madrid (马德里的老年痴呆症). In a series of tests, the study found the Spanish superagers scored lower than typical older adults in levels of depression and anxiety. Mental health issues such as depression are known risk factors for developing dementia(痴呆).

Superagers also told researchers they had been more active in midlife, had been happy with the amount of sleep they got, and were independent in their daily living. Poor sleep is a key risk factor for cognitive decline. “This study adds to what we already know—superaging isn’t just the ability to perform well on a cognitive test,” said Angela Roberts, an assistant joint professor of communication and computer science at Western University in London, Ontario, in an email.

When did you last see a polar (极地的) bear? On a trip to a zoo, perhaps? If you had attended a winter activity in New York a few years ago, you would have seen a whole polar bear club. These “Polar Bears” are people who meet frequently in winter to swim in freezing cold water. That day, air temperature was 3℃, and the water temperature was a bit higher. The members of the Polar Bear Club at Coney Island, New York are usually about the age of 60. Members must satisfy two requirements. First, they must get along well with everyone else in the group, this is very important because there are so many different kinds of people in the club. Polar Bears must also agree to swim outdoors at least twice a month from November through February.

Doctors do not agree about the medical effects of cold-water swimming. Some are worried about the dangers of a condition in which the body’s temperature drops so low that finally the heart stops. Other doctors, however, point out that there is more danger of a heart attack during summer swimming because the difference between the air temperature and water temperature is much greater in summer than in winter.

The Polar Bears themselves are satisfied with the benefits (or advantages) of cold-water swimming. They say that their favorite form of exercise is very good for the circulatory system (循环系统) because it forces the blood to move fast to keep the body warm. Cold-water swimmers usually turn bright red after a few minutes in the water. A person who turns blue probably has a very poor circulatory system and should not try cold-water swimming.

The main benefits (or advantages) of cold-water swimming are probably mental (精神的). The Polar Bears love to swim year-round; they find it fun and relaxing. As one 70-year-old woman says, “When I go into the water, I pour my troubles into the ocean and let them float away (漂走).”