In adults with type 2 diabetes, a combination of seven healthy lifestyle habits, including sleeping seven to nine hours per day, exercising regularly, and having frequent social interaction, was related to a decreased risk of dementia.

The findings of the study were published in the online issue of Neurology, the medical journal of the American Academy of Neurology. "Type 2 diabetes is a worldwide epidemic that affects one in 10 adults, and having diabetes is known to increase a person's risk of developing dementia," said study author Yingli Lu, MD, PhD, of Shanghai Jiao Tong university school of medicine in China.

"We investigated whether a broad combination of healthy lifestyle habits could offset that dementia risk and found that people with diabetes who incorporated seven healthy lifestyle habits into their lives had a lower risk of dementia than people with diabetes who did not lead healthy lives."

For the study, researchers looked at a health care database in the United Kingdom and identified 167,946 people 60 or older with and without diabetes who did not have dementia at the start of the study. Participants completed health questionnaires, provided physical measurements and gave blood samples.

For each participant, researchers calculated a healthy lifestyle score of zero to seven, with one point for each of the seven healthy habits.

Habits included: No current smoking, moderate alcohol consumption of up to one drink a day for women and up to two a day for men, regular weekly physical activity of at least 2.5 hours of moderate exercise or 75 minutes of vigorous exercise, and seven to nine hours of sleep daily. Another factor was a healthy diet including more fruits, vegetables, whole grains and fish and fewer refined grains, processed and unprocessed meats.

The final habits were being less sedentary, which was defined as watching television less than four hours a day, and frequent social contact, which was defined as living with others, gathering with friends or family at least once a month and participating in social activities at least once a week or more often.

Researchers followed participants for an average of 12 years. During that time, 4,351 people developed dementia. A total of 4% of the people followed only zero to two of the healthy habits, 11% followed three, 22% followed four, 30% followed five, 24% followed six and 9% followed all seven.

People with diabetes who followed two or fewer of the seven healthy habits were four times more likely to develop dementia than people without diabetes who followed all seven healthy habits. People with diabetes who followed all of the habits were 74% more likely to develop dementia than those without diabetes who followed all the habits.

For people with diabetes who followed all the habits, there were 21 cases of dementia for 7,474 person-years or 0.28%. Person years represent both the number of people in the study and the amount of time each person spends in the study. For people with diabetes who followed only two or fewer habits, there were 72 cases of dementia for 10,380 person-years or 0.69%.

After adjusting for factors like age, education and ethnicity, people who followed all the habits had a 54% lower risk of dementia than those who followed two or fewer. Each additional healthy habit people followed was associated with an 11% decreased risk of dementia.

The association between healthy lifestyle score and dementia risk was not affected by medications people took or how well they controlled their blood sugar.

"Our research shows that for people with type 2 diabetes, the risk of dementia may be greatly reduced by living a healthier lifestyle," Lu said. "Doctors and other medical professionals who treat people with diabetes should consider recommending lifestyle changes to their patients. Such changes may not only improve overall health but also contribute to prevention or delayed onset of dementia in people with diabetes."

A limitation of the study was that people reported on their lifestyle habits and may not have remembered all details accurately. Lifestyle changes over time were also not captured.