Being overweight or obese in middle age reduces the risk of dementia in old age, according to a UK study published this month in The Lancet Diabetes & Endocrinology.
Researchers analyzed two decades’ worth of medical records for almost 2 million people, concluding that those who were underweight had a 39 percent higher risk of dementia, while being overweight or obese reduced dementia risk by 18-24 percent.
“It is a surprise," lead researcher Dr. Nawab Qizilbash told BBC News. "The controversial side is the observation that overweight and obese people have a lower risk of dementia than people with a normal, healthy body mass index.”
"That's contrary to most if not all studies that have been done, but if you collect them all together our study overwhelms them in terms of size and precision."
Qizilbash said researchers did not know why obesity would protect against dementia, and cautioned, "You can't walk away and think it's OK to be overweight or obese.” Obesity is still linked to diabetes, heart disease and other health problems.
Researchers speculated that nutritional factors may explain why those who eat more experience less dementia. A healthy, but not necessarily low calorie, diet may protect against dementia, Deseret News recently reported.
A recent statistical study by researchers at Rush University showed that the MIND diet, a simplified version of the Mediterranean diet, reduced the risk of Alzheimer’s by as much as 53 percent.
The main components of the MIND diet are whole grains, vegetables, legumes, walnuts, berries, fish, poultry and red wine or grape juice. Fried foods, butter, high fat dairy, high fat meats, sweets and baked goods are limited with the MIND diet.
A program of healthy diet, exercise and brain training also shows promise for preventing dementia, according to a Swedish study published last month in The Lancet, a British medical journal.
Researchers offered a comprehensive program of nutritional counseling, exercise activities and brain training to a group of several hundred Finnish seniors at risk of dementia. Seniors participating in the study ate a healthy diet similar to the MIND diet, exercised 2-5 times per week, and did brain training exercises.
After two years, “overall scores in brain tests were 25 percent higher” for seniors participating in the program than for a similar group of seniors who did not participate, The Daily Mail reported.