Liraglutide, a GLP-1 analogue now available for the treatment of obesity (as Saxenda) in North America, works by reducing appetite and increasing satiety, thus making it easier to lose weight and keep it off (with continuing treatment).

Now, a study by Olivia Farr and colleagues, in a paper published in Diabetologia not only present data showing the presence of GLP-1 receptors in human cortex, hypothalamus and medulla, but also provide functional evidence for altered  brain response to food cues.

After documenting the presence of GLP-1 receptor in human brains using immunohistochemistry, the researchers conducted a randomised controlled placebo-controlled, double-blind, crossover trial in 18 individuals with type 2 diabetes who were treated with placebo and liraglutide for a total of 17 days each (0.6 mg for 7 days, 1.2 mg for 7 days, and 1.8 mg for 3 days).

Using functional MRI neuroimaging studies, the researchers found that liraglutide remarkably decreased activation of the parietal cortex in response to highly desirable (vs less desirable) food images.

They also observed decreased activation in the insula and putamen, areas involved in the reward system.

Furthermore, using neurocognitive testing, the researchers showed that increased ratings of hunger and appetite correlated with increased brain activation in response to highly desirable food cues while on liraglutide.

In contrast, ratings of nausea (a well-known side effect of liraglutide) correlated with decreased brain activation.

As the authors note,

“Our data point to a central mechanism contributing to, or underlying, the effects of liraglutide on metabolism and weight loss.”

These findings no doubt match the reports from my own patients of experiencing less interest in highly palatable foods and finding it much easier to pass up on foods that they would have otherwise found hard to resist.

Clearly, as we learn more about brain function in eating behaviour, we are thankfully moving towards treatments that are clearly proving to be far more effective than just telling patients to “simply eat less” (which I have often likened to telling people with depression to “simply cheer up”).

@DrSharma
Edmonton, Canada

Disclaimer: I have received honoraria for speaking and consulting from Novo Nordisk, the maker of liraglutide

(c) Dr. Sharma’s Obesity Notes – Read entire story here.