It is well established that being overweight can raise the risk of diabetes, heart disease and stroke. But according to a new study, it may also have consequences for cognitive health; researchers found that young adults who were overweight or obese had poorer episodic memory than their healthy-weight peers.
Study coauthor Dr. Lucy Cheke, of the Department of Psychology at the University of Cambridge in the UK, and colleagues publish their findings in The Quarterly Journal of Experimental Psychology.
According to the Centers for Disease Control and Prevention (CDC), around 69% of American adults aged 20 and older are overweight or obese, putting them at greater risk for numerous health problems, including high blood pressure, heart disease, type 2 diabetes and some types of cancer.
Increasingly, researchers have found that excess weight may also impact brain health. Last September, for example, Medical News Today reported on a study that linked overweight and obesity in midlife to earlier onset of Alzheimer's disease.
"While the physical health impacts of obesity are increasingly well understood, recent research indicates that there may be a significant psychological element to the obese syndrome," the authors note, "with proposals that cognitive deficits may occur both as a result of obesity and potentially as a causal factor in its emergence."
Higher BMI linked to poorer performance on memory test
To further investigate this link, Dr. Cheke and colleagues enrolled 50 young adults aged 18-35 to their study, which investigated how body mass index (BMI) may influence episodic memory - the ability to recall past events.
All participants had a BMI of 18-51; a BMI of 18-25 was deemed healthy, 25-30 was considered overweight and 30 or over was classified as obese.
Subjects were required to complete a memory test called the "Treasure-Hunt Task," which involved hiding a number of objects around complex scenery - such as a desert with palm trees - on a computer screen over a 2-day period. Participants were then asked to recall which objects they had hidden and when and where they hid them.
Compared with participants who had a healthy BMI, the team found that those whose BMI fell into the categories of overweight or obese had a poorer performance on the memory task, with performance worsening as BMI increased.
The researchers say their findings indicate that a higher BMI may lead to structural and functional changes in the brain that reduce the ability to form and recall episodic memories.
What is more, the team says reduced episodic memory as a result of higher BMI may also have a negative impact on a person's ability to adhere to a healthy diet.
Dr. Cheke explains:
"We're not saying that overweight people are necessarily more forgetful, but if these results are generalizable to memory in everyday life, then it could be that overweight people are less able to vividly relive details of past events - such as their past meals. Research on the role of memory in eating suggests that this might impair their ability to use memory to help regulate consumption.
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."
The authors note that their study was small and preliminary, so further research is warranted to confirm the findings and determine whether they may apply to older adults who are overweight or obese.
Still, the team believes the study brings us a step closer to gaining a better understanding of the psychological factors that may drive obesity.
"By recognizing and addressing these psychological factors head-on," notes study coauthor Dr. Jon Simons, also of the Department of Psychology at Cambridge, "not only can we come to understand obesity better, but we may enable the creation of interventions that can make a real difference to health and well-being."
Earlier this month, a study reported by MNT found that a person's health behavior and obesity risk may be influenced by their neighborhood.