SPECT Scan Reveal Link Between Obesity, Brain Blood Flow, and Alzheimer’s

CT scans have revealed a link between weight and brain function – the more a patient weighs, the higher their levels of brain dysfunction.

In a recent article published in the Journal of Alzheimer’s Disease, investigators from Amen Clinics discussed the link between body mass index (BMI) and areas of the brain that are most vulnerable to Alzheimer’s damage. With 72 percent of Americans falling into the overweight or obese categories, these findings could have a far-reaching impact.

“This study shows that being overweight or obese seriously impacts brain activity and increases the risk of Alzheimer’s disease, as well as many other psychiatric and cognitive conditions,” said lead study author Daniel G. Amen, M.D., Amen Clinics founder.

This figure showed 3-D renderings of resident perfusion averaged across normal BMI (BMI = 23), overweight (BMI = 29), and obese (BMI = 37) men, each 40 years of age. Courtesy: Journal of Alzheimer's disease

For this study, researchers from Amen Clinics, a network of outpatient mental health clinics nationwide, analyzed more than 35,000 functional neuroimaging scans using single-photo emission CT (SPECT) from more than 17,000 individuals ages 18 to 94, measuring blood flow and brain activity. This study is the largest to link obesity with brain function, they said.

Based on their study results, Amen’s team determined that blood flow – the No. 1 brain imaging predictor of the likelihood of Alzheimer’s development – progressively decreased as a person’s weight increased. This phenomenon was seen in brain areas that can be most affected by Alzheimer’s – the temporal and parietal lobes, hippocampus, posterior cingulate gyrus, and precuneus -- they said. These findings were the same during cognitive tests, as well as while patients remained still.

These CT findings bolster the growing perception of Alzheimer’s as a lifestyle disease, said Geroge Perry, Ph.D., chair of neurobiology at the University of Texas at San Antonio. By showing how obesity alters blood supply to the brain, promoting Alzheimer’s, he said, these results are a “major advance” in helping patients understand that lifestyle changes can help prevent Alzheimer’s.

Amen agreed with Perry’s assessment that these findings can be clinically impactful.

“One of the most important lessons we have learned through 30 years of performing functional brain imaging studies is that brains can be improved when you put them in a healing environment by adopting brain-healthy habits,” he said, “such as a health calorie-smart diet and regular exercise.”