Progression of anorexia nervosa: An insight into neurological and biological mechanisms influencing the personality patterns of anorexics

Anorexia nervosa has emerged as a prominent eating disorder affecting young women. This disorder's fundamental characteristic is an abnormally low weight achieved by severe calorie restriction and refusal to maintain body weight at or above the minimally normal weight for age and height. It is a complex disorder with its origins still not explicitly defined. In anorexic individuals, an imbalance in the molecular signalling and hypothalamic neuropeptides is believed to be significantly responsible for alterations in the biological mechanisms associated with body weight, appetite and energy homeostasis. The imbalance between the genetic systems such as serotonin, dopamine, brain-derived neurotrophic factor, estrogen and their interactions are significantly observed in anorexic as well as recovered anorexic individuals. The dopaminergic pathway is involved in reward mechanisms but its dysfunction might cause weight loss, food aversion, hyperactivity, obsessive compulsive behaviours, distorted body image. An abnormal serotonin function reveals personality traits such as rigidity, inhibition, anxiety, inflexibility, perfectionism and harm avoidance. The Met66 variant of brain derived neurotrophic factor is strongly associated with the development of restricting-type anorexia nervosa. The development of anorexia has been linked to estrogen receptor beta gene variants, which also regulate food intake and states of anxiety and depression.This review discusses the neurobiological dysregulations because of which anorexics tend to have a distinct personality profile characterized by behaviour patterns comprising perfectionism, obsessive-compulsive disorder, harm avoidance, alexithymia, anger suppression, anxiety, rigidity, novelty seeking, anhedonia, depression, impulsivity, substance abuse, self harm etc. Heterogeneities in the characteristic profile are observed based on the subdivisions of anorexia nervosa. The impact of malnutrition has also been scrutinized.