A recent study from the University of Cambridge has discovered evidence that obesity may affect episodic memory and other brain functions. Previous studies have linked obesity to dysfunction in the parts of the brain that involve memory, learning, decision making, problem solving and emotions. Researchers in the new study wanted to find out whether obesity could have a direct effect on memory.
Dr. Lucy Cheke said, “Increasingly, we’re beginning to see that memory – especially episodic memory, the kind where you mentally relive a past event – is also important.” This includes how vividly a recent meal is remembered making a difference in feelings of hunger and how much is likely to be eaten later on.
The study involved 50 participants between the ages of 18 and 35, with body mass indices (BMI) between 18 and 51. BMIs of 25-30 are considered overweight. A BMI of more than 30 is obese. Nearly 69 percent of U.S. adults are overweight or obese. People who are obese are at higher risk for both physical and mental health problems, including heart disease and diabetes, depression and anxiety.
Participants in the study completed a “Treasure-Hunt Task” memory test. For two days they hid items around complex scenes, such as a desert with palm trees. They were then asked to remember what they had hidden where and when. Participants with higher BMI performed more poorly on the tasks, which researchers say may indicate that structural and functional changes in the brain that are found in people with higher BMIs may go along with a lowered ability to form and/or retrieve episodic types of memory.
Cheke said the findings of the study do not mean that overweight people are generally more forgetful, but that it is possible that they have less ability to vividly relive the details of a past event, such as a past meal. Research on the role of the relationship between memory and eating suggests that this memory dysfunction might impair the ability of overweight people to use memory to regulate how much they eat.
“In other words, it is possible that becoming overweight may make it harder to keep track of what and how much you have eaten, potentially making you more likely to overeat,” says Cheke. In addition, she says that psychological factors play an important role in driving feelings of hunger. Although the balance of hormones in the body and brain drives hunger feelings to some extent, psychological factors are important. For instance, people tend to eat more when distracted, and to “comfort eat” when sad.
The researchers caution that further research is needed to determine whether the study’s findings can be generalized to all overweight individuals, since the participants in the study were all young adults.