Women affected by eating disorder-related binging and purging behaviors experience greater declines in their memory function than women with eating disorders who heavily restrict their food intake, according to evidence recently reported by a group of Canadian scientists.
Some women with an eating disorder manifest their condition by severely restricting their food intake. However, others binge on food periodically and then purge the calories from their bodies. In a study published in 2015 in the Journal Psychiatry Research: Neuroimaging, researchers from three Canadian institutions compared the memory function in women who heavily restrict their food intake to the memory function in women who binge on food and subsequently engage in purging behaviors. The researchers specifically focused on a form of memory called working memory.
Restrictive Eating Disorders
The classic example of a restrictive eating disorder is anorexia nervosa. People with this condition develop a severe fear of gaining weight and/or appearing fat, even though their body weight is at least 15% below the commonly accepted standard for their height and age. The vast majority of people in the U.S. with anorexia are girls or women. Specific approaches to food restriction associated with the illness include heavily limiting the types of food viewed as acceptable for consumption, avoiding eating altogether when possible, avoiding having someone else present when eating and “playing” with food to simulate the eating process without actually swallowing much food.
Binging/Purging Eating Disorders
The classic example of a binging/purging eating disorder is bulimia nervosa. People with this condition also have fears about their appearance but manifest these fears by periodically eating excessive amounts of food and then eliminating the consumed calories through intentional vomiting or the misuse of laxatives, diuretics or enemas. However, binging/purging behaviors are not limited to people with bulimia. A relatively small subset of people with anorexia also occasionally eat excessively and use vomiting or laxatives, diuretics or enemas to eliminate calories. A person with anorexia may also participate in purging after consuming relatively small amounts of food. (The single most common eating disorder, binge-eating disorder, centers on periods of excessive food intake unaccompanied by any purging behaviors.)
Working memory is the accepted term for a form of short-term memory that lets you store relevant information in a rapidly accessible and usable form. Part of your working memory
relies on sound-based input, while the remainder relies on visual-spatial input. All human beings need a functional working memory to do such critically important things as make sense of newly acquired information, follow complex instructions, maintain focus and an accurate orientation to ongoing reality, perform mathematical calculations and read. Deficiencies in any of these abilities can significantly impair the ability to maintain a self-supporting daily routine.
Impact of Eating Disorder Subtypes
In the study published in Psychiatry Research: Neuroimaging, researchers from Canada’s Douglas University Institute, McGill University and Montreal Neurological Institute used a small-scale project involving 46 women to compare the memory function-related impact of restrictive eating disorder subtypes to the memory function-related impact of binging/purging eating disorder subtypes. Nineteen of the study participants only had indications of a restrictive eating disorder, while the remaining 27 participants only had indications of a binging/purging eating disorder. For each group of participants, the researchers used real-time fMRI (functional magnetic resonance imaging) scans to measure the brain’s ability to use memory while performing a series of relatively complicated tasks.
After reviewing the fMRI results, the researchers concluded that, compared to the women affected by a restrictive eating disorder subtype, the women affected by a binging/purging eating disorder subtype had a substantially lower level of activity in a brain area responsible for a specific form of working memory, as well as the ability to plan muscle movements in advance and the ability to take uncertainty into account when engaged in decision-making and logical thinking.
The study’s authors believe their findings point to a greater degree of working memory disruption in the brains of women affected by eating disorder-related binging and purging rather than eating disorder-related excessive food restriction. They also believe their findings point to additional impairments in higher-level mental function (also known as executive function) in women with eating disorders who engage in recurring cycles of food binging and food purging.