In the largest study of its kind, brain scans show people who are overweight and obese have a greater chance of reduced blood flow and brain activity. Scientists say low blood flow is a risk factor in developing Alzheimer's disease.
Psychiatrist Dr. Daniel Amen and his team looked at 35,000 brain scans from more than 17,000 patients and discovered all brain regions, including those affecting Alzheimer's patients, had reduced blood flow if patients were overweight, obese or morbidly obese.
His study, published in the Journal of Alzheimer's Disease, is said to be the most important breakthrough in a decade.
Dr. Amen talks about the study on his Facebook page, saying he was stunned when looking at the graphs showing the decline in blood flow.
"I mean, just critically important areas of the brain and we looked at someone with a healthy BMI, someone who is overweight and someone who is obese and you can just see the decrease in blood flow in the brain, " he says.
Dr. Rhonna Shatz is medical director of UC Health's Memory Disorders Center. She noticed many of her Alzheimer's patients are overweight. "Yes, that's definitely a factor that we look at and talk about," she says.
Although she had seen the correlation between blood flow and Alzheimer's before, she is interested in Dr. Amen's study because it investigated a "massive number of people."
Shatz does have questions about the study, wondering if medicines could have played a part, because she says they can sometimes lower circulation. Also, what about sleep apnea? "High BMI and Alzheimer's disease have a strong association with sleep apnea. And we know sleep apnea has some association with low circulation and inflammation," Shatz says.
Dr. Amen says he hopes to understand the mechanism and then can better understand obesity and the mind.
"I have no interest in having an older brain and I don't want you to have an older brain either," says Amen.
The latest statistics show 72% of Americans are overweight. Forty-two percent of those are obese.