Taking the weight loss drug lorcaserin could result in a decrease in the response to food cues in areas of the brain that are associated with attention and emotion, a team led by scientists at the Beth Israel Deaconess Medical Center (BIDMC) in Boston revealed. The drug could lead to a decrease in caloric intake, weight and body mass index (BMI).

The paper, which was published Monday in the journal Diabetes of the American Diabetes Association, is the first study of the drug lorcaserin in the human brain, according to the researchers. During the study, the researchers revealed the mechanism underlying the drug's efficacy and also provided details on how individuals may benefit most from the medication.

"Human feeding behaviors involve areas of the brain responsible for cognitive control and decision-making," Christos S. Mantzoros, MD, director of the Human Nutrition Unit in the Division of Endocrinology, Diabetes and Metabolism at BIDMC and professor of medicine at Harvard Medical School, said in a press release. "We wanted to find out if lorcaserin was acting on these brain regions and, if so, where and how. One-third of the U.S. population is obese, and another one-third is overweight. This is a huge burden on individuals and the health care system. In addition, it increases the risk of diabetes, cardiovascular disease and many types of cancer. We need to continue to develop safe and effective therapies to combat this epidemic."

The drug, which was approved by the U.S. Food and Drug Administration in 2012, is mostly prescribed for obese or overweight adults who also have weight-related health complications such as diabetes.

Studies linked to the drug have shown that it helps about half of the people who take it, resulting in more than 5 percent loss of their body mass within a year. However, the variability in individual results are high, and the mechanism underlying its effect was previously unknown.

The latest study was conducted with the help of Mantzoros and his colleagues observing 48 obese men and women. Of these, half took the drug, half took a placebo over the course of a four-week experiment.

Blood and physical examinations, measurements and weight-loss counseling with a registered dietician were conducted on participants who visited the clinic four times. During the study, the participants were also expected to keep records of the food they ate.

The first visit was conducted before receiving the medication and the next was after a week of medication (Week 1), while the third came after four weeks of medication (Week 4). After three visits, the exams were followed by two brain scans, one after the patients had fasted for at least 12 hours, the other after they had eaten a meal.

The scans were taken using functional magnetic resonance imaging (fMRI) to measure changes in blood flow in an active brain, which suggests which regions play a role during a given task.

During each scan, participants were shown 150 images of different types of food — some considered desirable such as cakes and onion rings, and some generally considered less desirable like vegetables, and also nonfood items like rocks and trees.

At Week 1, the fMRI scans in the fasting state showed that the participants taking the drug had decreased brain activity in response to images of highly desirable foods "in the attention-related parietal and visual cortices."

At Week 4, the lorcaserin group showed less activity "in the parietal cortex - which is responsible for integrating sensory information - when looking at any of the food images."

The study also revealed that those who had the strongest brain responses to food prior to taking lorcaserin benefited the most with the weight-loss medication.

"Decreases in caloric intake, weight, and BMI were linked to strong responses to food cues in the areas of the brain related to emotion, pleasure and attention prior to taking the weight-loss drug, which suggests that lorcaserin could prove to be of particular benefit to 'emotional eaters,' " Mantzoros said.

"In addition, the different mechanism of action in comparison to other drugs for obesity creates an opportunity for combination drugs for the treatment of obesity," Mantzoros said. "This might create more powerful solutions and is something that remains to be explored."

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