Imaging studies provide clues as to how obesity increases the risk of Alzheimer’s disease.

New data from a large brain imaging study has found a consistent link between weight gain and reduced cerebral blood flow,media reported. The study provides more insight into the link between Alzheimer’s disease and obesity, suggesting that maintaining a healthy weight directly reduces the risk of dementia.

Imaging studies provide clues as to how obesity increases the risk of Alzheimer's disease.

Previous epidemiological studies have provided depressingly inconsistent results as researchers try to establish a clear link between obesity in middle age and the development of dementia in later life. However, a convincing 2017 study found that obesity appears to be directly related to cognitive decline, and that weight loss can lead to significant improvements in cognitive function.

In a new study conducted by the U.S. team, brain scans of more than 17,000 subjects were analyzed to investigate the link between weight and blood flow to the brain. The patterns detected were so alarming that the larger the BMI, the lower blood flow in some brain regions.

The observed decrease in cerebral blood flow was particularly pronounced in the five key brain regions associated with Alzheimer’s subjects — the temporal lobes, the top lobes, the hippocampus, the back buckles and the pre-wedge lobes.

“This study shows that being overweight or obese can seriously affect brain activity and increase the risk of Alzheimer’s disease and many other mental and cognitive diseases,” explained Daniel Amen, lead author of the study.

Imaging studies provide clues as to how obesity increases the risk of Alzheimer's disease.

The study did not explore how too much weight might directly lead to a decrease in blood flow to these brain, but the researchers did hypothesized several potential mechanisms that might play a role. These mechanisms include changes in hormone levels associated with obesity, or systemic inflammation caused by being overweight.

“The relationship between obesity and brain physiology may occur through several mechanisms,” the researchers wrote. “One is through nerve inflammation and its effect on perfusion. Obesity is a known systemic pro-inflammatory state. Neuroinflammation is associated with low infusions in the brain through pathways including TREM-2, a biomarker of neuroinflammation that has also been documented in AD (Alzheimer’s disease). Therefore, chronic obesity and its associated systemic inflammation i triggered a result of neuroinflammation and low perfusion. “

It is not clear what long-term effects these changes in cerebral blood flow have. Again, this is not the scope of this particular study. Instead, the study is certain that there is a reasonable direct relationship between weight and blood flow to the brain.

George Perry, editor-in-chief of the Journal of Alzheimer’s Disease, suggests that the new study provides strong evidence of how the brain is directly affected by broader physiological changes. This confirms the potential of middle-aged lifestyle interventions to play an important role in reducing a person’s risk of cognitive decline in later life.

“Receiving Alzheimer’s disease is a lifestyle disease that is no different from other age-related diseases, and it’s the most important breakthrough in a decade,” said Perry, who was not involved in the new study. “Dr. Amen and his co-authors provide compelling evidence that obesity alters the blood supply to the brain, shrinks the brain and promotes the development of Alzheimer’s disease. This is a significant step forward because it is a direct testament to the brain’s response to our bodies. “

The new study was published in the Journal of Alzheimer’s Disease.