Many memory impairments exist as a result from or cause of eating disorders. Eating disorders (EDs) are characterized by abnormal and disturbed eating patterns that affect the lives of the individuals who worry about their weight to the extreme. These abnormal eating patterns involve either inadequate or excessive food intake, affecting the individual's physical and mental health.
In regard to mental health, individuals with eating disorders appear to have impairments in executive functioning, visual-spatial ability, divided and sustained attention, verbal functioning, learning, and memory.Lena, S. M, Fiocco, A. J, & Leyenaa. r, J. K, (2004). The role of cognitive deficits in the development of eating disorders. Neuropsychology Review. 14, 99 - 113 Some memory impairments found in individuals with eating disorders are due to nutritional deficiencies, as well as various cognitive and attentional biases. Neurobiological differences have been found in individuals with ED compared to healthy individuals, and these differences are reflected in specific memory impairments. There are certain treatments and effects of treatments, aimed at these ED-specific memory impairments. Animal research and areas of future research in relation to ED and memory, are also integral to understanding the effects of ED on memory. There are three particular diagnoses of eating disorders that have been linked to memory impairments: anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED).
Memory impairments
Memory biases Individuals with eating disorders show increased tendencies to direct their attention toward irregular eating-related thought processing and attentional bias compared to non-ED individuals.von Wietersheim, J., Kunzl, F., Hoffmann, H., Glaub, J., Rottler, E., & Traue, H. C. (2012). Selective attention of patients with anorexia nervosa while looking at pictures of their own body and the bodies of others: An exploratory study. Psychosomatic Medicine, 74(1), 107-113.Shafran, R., Lee, M., Cooper, Z., Palmer, R. L., & Fairburn, C. G. (2007). Attentional bias in eating disorders. The International Journal of Eating Disorders (Print), 40(4), 369-380.Butow, P. Beaumont, P. & Touyz, S. (1993) Cognitive processes in dieting disorders. International Journal of Eating Disorders, 14, 319-329. Studies have suggested a strong link between eating disorders and information processing, such as attention and memory. All types of eating disorders (bulimia nervosa, anorexia nervosa, and EDNOS) consistently display attentional biases towards disorder-related stimuli specific to their ED. Examples of disorder-related stimuli include food, shape, weight, and size. This heightened attention to disorder-related stimuli leads to higher levels of encoding, consolidation and retrieval of this information, acting as a potential cause for the mental maintenance of the disorder(s).Teckcan, A. İ., Taş, A. Ç., Topçuoğlu, V., & Yücel, B. (2008). Memory bias in anorexia nervosa: Evidence from directed forgetting. Journal of Behavior Therapy and Experimental Psychiatry, 39(3), 369-380.
Individuals with eating disorders display several memory and attentional biases to food, shape, weight and size.King, G. A., Polivy, J., & Herman, C. P. (1991). Cognitive aspects of dietary restraint: Effects on person memory. International Journal of Eating Disorders, 10, 313–321. Specific memory biases include: Directed-forgetting: individuals with eating disorders, particularly anorexia nervosa, display more difficulty in forgetting information or cues related to body, shape, and food than those without eating disorders. This leads to greater availability of such memories, facilitating the maintenance of the eating disorder. Schema-related: display maladaptive perceptions of food, shape, weight and self that lead to obsessive attention on and enhanced memory for these items,Fairburn, C.G., Cooper, Z., & Shafran, R. (2003). Cognitive-behaviour therapy for eating disorders: A ‘‘transdiagnostic’’ theory and treatment. Behaviour Research and Therapy, 41, 509–52. leading to maintaining the eating disorder thought and eating behaviour.Legenbauer, T., Maul, B., Rühl, I., Kleinstäuber, M., & Hiller, W. (2010). Memory bias for schema-related stimuli in individuals with bulimia nervosa. Journal of Clinical Psychology, 66(3), 302-316. Memories for these items are more easily encoded and retrieved compared to other information.Williamson, D.A., White, M.A., York-Crowe, E., & Stewart, T.M. (2004). Cognitive behavioral theories of eating disorders. Behavior Modification, 28, 711–738. Most of the research in this area has been on individuals with anorexia nervosa. Cued recall tasks, recognition tasks and Stroop task tests are used to study these effects.Lee, Michelle, and Roz Shafran. Information Processing Biases in Eating Disorders. Clinical psychology review 24.2 (2004): 215-38. Some studies have shown contradictory results to ED individuals' heightened attention and enhanced memory, however the difference could be attributed to an anxiety-induced response and avoidance behaviour. This could cause impairments in the individuals' ability to remember the information learned, and suggests that more research needs to be done in this area to better understand the relationship between schema-related biases and ED's. Selective memory bias: studies have been done on individuals with bulimia nervosa, suggesting selective memory bias exists for positive and negative weight-related items compared to emotional items.Hunt, J. & Cooper, M. (2001). Selective memory bias in women with bulimia nervosa and women with depression. Behavioural and Cognitive Psychotherapy, 29,1, 93-102. Biases towards food-related items were also found, a common finding in individuals with depression.
Explicit memory Patients with anorexia nervosa show a strong explicit memory bias towards anorexia-related words.Hermans, D., Pieters, G., Eelen, P. (1998). Implicit and explicit memory for shape, body weight, and food-related words in patients with anorexia nervosa and nondieting controls. Journal of Abnormal Psychology. 193–202. In one study, participants (AN group compared to a control group) were presented with a list of words divided into four categories: positive, negative, neutral, and anorexia-related. They were then tested explicitly with cued recall, and it was found that the AN participants better favored the anorexia-related words, showing a schema-related memory bias. Participants were also tested implicitly with word stem completion tests, but no implicit bias was found.
In another study, AN participants were found to have less ability to concentrate in the presence of explicit distractors, as well as to have a conscious cognitive bias towards illness-related words.Dickson, H., Brooks, S., Uher, R., Tchanturia, K., Treasure, J., et al. (2008). The inability to ignore: distractibility in women with restricting anorexia nervosa. Psychological medicine. 1741–1748. These explicit biases were associated with a longer duration of the illness. A different study characterized AN patients as having trouble integrating positive and negative experiences and that the length of the illness also affected these symptoms and reinforced these impairments.Nikendei, C., Funiok, C., Pfuller, U., Zastrow, A., Aschenbrenner, S., et al. (2011). Memory Performance in acute and weight-restored anorexia nervosa patients. Psychological Medicine. 829–838. The results of these studies suggest that there are clear differences in the explicit cognitive processing of stimuli between AN individuals and healthy controls and that the length of the illness can affect the extent of these memory biases.
A different study showed that currently ill AN patients had problems with immediate and delayed verbal recall; these disadvantages were also found in weight-restored AN individuals. There was no difference between healthy controls and AN patients in working memory, just memory function. This study demonstrates that there are not only memory biases found in AN individuals but memory impairments as well.
Autobiographical memory deficits have been found in individuals with AN. One study found that AN patients with a history of sexual abuse had impairments in their autobiographical memory characterized by their increased general memory recall.Dalgleish, T., Tchanturia, K., Serpell, L., Hems, S., Yend, J., De Silva, P., et al. (2003) Self-reported parental abuse relates to autobiographical memory style in patients with eating disorders. Emotion. 3, 211–22. Another study found that anorexic patients are characterized by an overgeneralization of both positive and negative autobiographical memories, which positively correlates with the duration of the illness.Nandrino, J.L., Doba, K., Lesne, A., Christophe, V., & Pezard, L. (2006) Autobiographical memory deficit in anorexia nervosa: Emotion regulation and effect of duration of illness. Journal of Psychosomatic Research. 61, 537–543. The impairment of both positive and negative memories suggests a general impairment in the access to emotional memories. Therefore anorexic patients are more prone to suppress or control not only negative but also positive affect. One hypothesis suggests that these more general memories are what allow these patients to reduce the impact of a negative event.Raes, F., Hermans, D., De Decker, A., Eelen, P., & Williams, J. (2003) Autobiographical memory specificity and affect regulation: an experimental approach. Emotion. 3, 201–206.
In one study, participants (bulimia nervosa patients and healthy controls) were exposed to television commercials that were neutral, food-related or body-related. Recall and recognition tests were carried out to test for an explicit memory bias. When compared to healthy controls, BN patients had less recall and recognition for body-related stimuli. This suggests that BN individuals avoid encoding/processing stimuli related to body image and have a selective memory bias.
Obese individuals with binge eating disorders have been compared with obese controls to see if there are different explicit memory biases between these two groups of people. It was found that both groups showed a bias towards negative words, but individuals with BED retrieved positive words less often.Svaldi, J., Bender, C., Tuschen-Caffier, B. (2010). Explicit memory bias for positively valenced body-related cues in women with binge eating disorder. J. Behav. Ther. * Exp. Psychiat. 41: 252-257 This demonstrates an explicit memory bias in which individuals with BED avoid encoding or pay less attention to positive words and focus their conscious attention almost exclusively on negative words. This is similar to the selective memory bias mentioned above.
Implicit memory
It was once thought that individuals with eating disorders had different implicit memory biases and attitudes towards food, depending on the type of eating disorder.Huijding, J. (2006). Implicit attitudes and psychopathology. Netherland Journal of Psychology. 58–60. BED was associated with a positive evaluation of food, and anorexia and bulimia were associated with a negative evaluation of food. This turns out not to be the case. There were no implicit differences in affective attitudes towards foods between high and low-restraint eaters. This suggests that regardless of the type of eating disorder, individuals with eating disorders view food in similar ways and attitudes towards food.