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NEDA TOOLKIT for Parents differences may have been present before the onset of the disorder (Kaye et al., 2001). Serotonin alterations in binge eating disorder appear fairly similar to those found in bulimia, although the research is more limited in this area. Researchers generally believe that individuals with BED also suffer from chronically low serotonin levels, which is thought to contribute to binge eating in an attempt to relieve the depressed mood caused (in part) by this low serotonin (Haedt-Matt & Keel, 2011). Genetics studies have supported this idea, as variants in a serotonin transporter gene were associated with increased binge eating severity in the general population (Akkermann et al., 2010). Further studies found an association between impulsivity and strict dieting with serotonin receptor genes and binge eating in young women (Racine et al., 2009). Dopamine Dopamine is commonly thought of as the “pleasure” chemical, due to its links with rewarding behaviors and drugs of abuse. Although dopamine is involved in reward-motivated behavior (such as studying to get good grades, or going to work early to get a raise), it also helps regulate movement, memory, hormones and pregnancy, and sensory processing (Beaulieu & Gainetdinov, 2011). Like serotonin, the overlap of processes controlled by dopamine and eating disorder- related symptoms caused researchers to investigate potential associations. In anorexia, the leading hypothesis is that the disorder is associated with an over-production of dopamine, leading to anxiety (Bailer et al., 2012a), harm avoidance (Bailer et al., 2012b), hyperactivity and the ability to go without pleasurable things like food (Kontis & Theochari, 2012). Research has shown that bulimia is associated with lower levels of both dopamine and certain of its receptors, and that binge eating is significantly associated with dopamine release in certain parts of the brain (Broft et al., 2012). Binge eating disorder has been linked to a hyper-responsiveness to rewards such as food, which makes eating more rewarding and pleasurable than in people without this disorder (Davis et al., 2012) and leads to a continuation of compulsive overeating (Bello & Hajnal, 2010). References Akkermann, K., Nordquist, N., Oreland, L., & Harro, J. (2010). Serotonin transporter gene promoter polymorphism affects the severity of binge eating in general population. Progress in Neuro-Psychopharmacology and Biological Psychiatry, 34(1), 111-114. doi: 10.1016/j.pnpbp.2009.10.008 Bailer, U. F., Narendran, R., Frankle, W. G., Himes, M. L., Duvvuri, V., Mathis, C. A., & Kaye, W. H. (2012). Amphetamine induced dopamine release increases anxiety in individuals recovered from anorexia nervosa. International Journal of Eating Disorders, 45(2), 263-271. DOI: 10.1002/eat.20937 Bailer, U. F., Frank, G. K., Price, J. C., Meltzer, C. C., Becker, C., Mathis, C. A., ... & Kaye, W. H. (2012b). Interaction between serotonin transporter and dopamine D2/D3 receptor radioligand measures is associated with harm avoidant symptoms in anorexia and bulimia nervosa. Psychiatry Research: Neuroimaging. doi:10.1016/j.pscychresns.2012.06.010 Bello, N. T., & Hajnal, A. (2010). Dopamine and binge eating behaviors. Pharmacology Biochemistry and behavior, 97(1), 25-33. doi: 10.1016/j.pbb.2010.04.016 Beaulieu, J. M., & Gainetdinov, R. R. (2011). The physiology, signaling, and pharmacology of dopamine receptors. Pharmacological reviews, 63(1), 182-217. doi: 10.1124/ pr.110.002642 Broft, A., Shingleton, R., Kaufman, J., Liu, F., Kumar, D., Slifstein, M., ... & Walsh, B. T. (2012). Striatal dopamine in bulimia nervosa: A pet imaging study. International Journal of Eating Disorders, 45(5), 648-656. DOI: 10.1002/eat.20984 Bruce, K. R., Steiger, H., Joober, R., Kin, N. M. K., Israel, M., & Young, S. N. (2005). Association of the promoter polymorphism− 1438G/A of the 5‐HT2A receptor gene with behavioral impulsiveness and serotonin function in women with bulimia nervosa. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics, 137(1), 40-44. Davis, C., Levitan, R. D., Yilmaz, Z., Kaplan, A. S., Carter, J. C., & Kennedy, J. L. (2012). Binge eating disorder and the dopamine D2 receptor: Genotypes and sub-phenotypes. Progress in Neuro-Psychopharmacology and Biological Psychiatry, 38(2), 328-335. doi: 10.1016/j.pnpbp.2012.05.002 Kontis, D., & Theochari, E. (2012). Dopamine in anorexia nervosa: a systematic review. Behavioural Pharmacology, 23(5 and 6), 496-515. doi: 10.1097/FBP.0b013e328357e115 Haedt-Matt, A. A., & Keel, P. K. (2011). Revisiting the affect regulation model of binge eating: A meta-analysis of studies using ecological momentary assessment. Psychological bulletin, 137(4), 660. doi: 10.1037/a0023660 You can read more about the effects of dopamine in the section on Reward. Page  | 70