Exercise and Brain Health

Anti-obesity Drug Improves Associative Learning

A new study published in the journal Nature Metabolism indicates that anti-obesity drug liraglutide can restore associative learning impairments caused by obesity—which can hinder motivation—after just one dose.

These are particularly hopeful results, especially considering that in a previous blog, we wrote about a study published in the June 13, 2023 edition of the journal Nature Metabolism in which researchers found that obesity changes how the brain views food—even after weight loss. More specifically, that study revealed that:

• Obesity appears to damage the brain’s ability to recognize the sensation of fullness and be satisfied after the person has consumed fats and sugars.

• The changes to the brain may not be reversible—even after significant weight loss.

The recent study around restoring associative learning impairments indicates that there’s still great potential to affect brain activity with interventions.

The New Research

A team at the Max Planck Institute for Metabolism Research in Germany carried out the research study, led by neuroscientist Marc Tittgemeyer. The team’s goal was to determine whether impaired insulin could also impact dopamine function, impairing the brain’s ability to learn via sensory association. To do so, they looked at two groups of participants:

1. Those with normal weight and high insulin sensitivity

2. Those with obesity who also had reduced insulin sensitivity

The randomized, placebo-controlled crossover functional magnetic resonance imaging (fMRI) study allowed the scientists to look at the participants’ brains after they were given either a placebo or liraglutide. After just one dose of the drug, there was no discernable difference in brain activity between the subjects with obesity and those of “normal” weight.

According to Dr. Tittgemeyer, the two-in-one effect of the drug not only treats obesity, but also improves the neural pathways of the brain to help people consciously lose weight.

“Interestingly, modern obesity treatment can normalize the learning of associations, thereby rendering people being susceptible again for sensory signals,” he explains, “hence, being prone again to react to more subliminal interaction, such as weight-normalizing diets and conscious eating. We showed that with obesity, there are disrupted circuit mechanisms that lead to impaired learning about sensory associations. Essentially that means that information provided by sensory systems, which the brain must interpret to select a behavioral response, are out of tune, or not balanced to homeostatic needs.”

Next Steps

Next up: determining what role liraglutide plays on a molecular level, as well as whether other methods of boosting insulin sensitivity show similar boosts to restoring learning impairments.

Also, the authors reported that the study design didn’t allow for testing of meaningful sex differences. It’s also worth noticing that all participants were medication-free and nonsmokers. In addition, none had any history of neurological, psychiatric, gastrointestinal or eating disorders and did not have any special diets. 

MBJ

Wendy Burt-Thomas writes about the brain, mental health and parenting.

Check out the original research:

https://www.nature.com/articles/s42255-023-00859-y

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