Causes of Anorexia nervosa

The causes of anorexia nervosa are unknown. In addition to the gender factor (women), a number of other risk factors have been identified. In Western society, completeness is considered unattractive and unhealthy, so the desire for harmony is widespread even among children. Over 50% of prepubescent girls use diets or other methods of controlling body weight. Excessive self-weight concerns or the use of diets in a history are predictors of increased risk, especially in people genetically predisposed to anorexia nervosa. Studies of monozygotic twins indicate concordance of more than 50%. Family and social factors are probably important. Many patients belong to the middle and upper socio-economic classes; they are scrupulous, compulsory and intelligent, they have a very high level of achievement and success.

The causes of anorexia are an unsolved problem. Foreign authors often interpret its emergence from the standpoint of Freudianism as "unconscious escape from sexual life", "desire to return to childhood," "rejection of pregnancy," "frustration of the oral phase," etc. However, psychoanalytic concepts do not explain the manifestations of the disease, on the contrary , they lead to a misunderstanding of them. In the formation of anorexia nervosa and its development, both the change in the psyche and the humoral factors play a role.

The causes of anorexia must also be sought in premorbid personality traits, physical and mental development, upbringing, and microsocial factors. Anorexia nervosa occurs in the pre-, post- and actually pubertal period, ie, the background is the disregulatory changes in the endocrine system, characteristic for this period. The formation of the bulimic form of anorexia nervosa is also associated with premorbid features of the hypothalamic-pituitary system. It is also established that fasting, leading to exhaustion, causes secondary neuroendocrine and metabolic changes, which in turn affect the function of brain cerebral structures, causing changes in the psyche. A vicious circle of psychobiological disorders is formed. The possible role of the system of opioid peptides in the regulation of food behavior in patients is examined.

[1], [2], [3]

Endocrine causes of anorexia

Endocrine disorders in anorexia nervosa. The presence of amenorrhea was one of the diagnostic criteria for anorexia nervosa. It is violations of menstrual function often cause patients to first seek medical attention. The question of the primary or secondary nature of these changes is widely discussed. The most common point of view, according to which the loss of menstruation occurs again, due to loss of body weight. In connection with this, a provision was made on the critical mass of the body - a sufficiently individual weight threshold, at which amenorrhea occurs. However, in a large part of the patients, menstruation disappears already at the very beginning of the disease, when there is no body mass deficit, i.e., amenorrhea is one of the first symptoms. It is known that when the body weight is restored to the value at which the loss of menstrual function occurred, the latter is not restored for a long time. This makes it possible to think about the primacy of hypothalamic disorders, manifested against the background of special eating behavior in such patients. It is possible that in the rehabilitation of body weight, the fat tissue / body weight ratio may not be restored, and this is necessary for normal menstrual function. With the violation of this relationship, the pathogenesis of amenorrhea in athletes is also associated.

Studies of gonadotropic secretion revealed a decrease in circulating pituitary and ovarian hormones. When administered to patients with lyuliberin, there is a decrease in LH and FSH in comparison with healthy ones. The question of the possibility of treating him with amenorrhea associated with disorders at the hypothalamic level is discussed. A correlation was found between the hormonal and somatic changes that are responsible for maintaining amenorrhea. Psychogenic factors are important during periods of recovery of menstruation and the onset of disturbances.

The study of secretion and metabolism of sex steroids showed an increase in testosterone and a decrease in estradiol, which is explained by a change in the function of the enzyme systems involved in the synthesis of these steroids and metabolism in tissues.

In patients with bulimia, amenorrhea occurs more often without significant body mass deficit. It is possible that the special "vomiting" behavior of patients corresponds to changes in the system of neuropeptides, neurotransmitters of the brain, which affect the hypothalamic mechanisms of regulation of menstrual function.

Laboratory studies show that levels of free T ₄, total T ₄, TSG are normal, but serum T ₃ in patients with severe body weight deficiency is reduced, and thyroid pituitary (TSH) remains normal, i.e., the paradoxical insensitivity of the pituitary gland to a decrease T ₃. However, when tyroliberine is administered, an outgrowth of TSH is noted, which indicates normal connections of the hypothalamus-pituitary gland. The decrease in T _{3 is} caused by the change in the peripheral transition of T ₄ to T ₃ and is regarded as a compensatory reaction, which contributes to the conservation of energy in conditions of exhaustion and body weight deficiency.

In patients with anorexia nervosa, an increase in plasma cortisol has been established, which is associated with a disorder in the hypothalamus-pituitary-adrenal system. To study the pathophysiology of these disorders, patients were injected with a corticotropin-releasing factor. At the same time, a significantly reduced response of ACTH to stimulation was noted. The change in the rhythm of cortisol secretion, the lack of suppression when performing a sample with dexamethasone are observed in some mental disorders that are not accompanied by a deficiency in body weight. A number of authors indicate a change in the function of adrenal enzymes in patients with anorexia nervosa, regulated propiocortin. The decrease in urinary excretion of 17-ACS is associated with a disruption in the metabolism of cortisol and renal function.

Of particular interest is the state of carbohydrate metabolism in patients with bulimia. They have metabolic signs of starvation (elevated beta-hydroxybutyric acid and free fatty acids in the blood) without significant body mass deficiency, as well as in patients with refusal to eat and lose weight, as well as a decrease in glucose tolerance, a change in insulin secretion. These factors can not be explained only as secondary, due to weight loss and weight loss, they can be associated with a particular eating behavior.

Patients with a refusal to eat have chronic hypoglycemia. In the literature there are descriptions of hypoglycemic comas in patients with anorexia nervosa. Reduction of the insulin content is, apparently, connected with the state of chronic fasting. The level of glucagon in a long-term disease remains normal, increases only in the first days of refusal of food. When glucose load, its level does not differ from that of healthy ones. Anorexia nervosa occurs in young girls with diabetes mellitus. Then it is the cause of the inexplicable labile course of the disease.

The level of somatotropin is increased in case of severe condition of patients and significant deficiency of body weight. There is a paradoxical reaction with glucose. In the literature there are reports of osteoporosis in patients with this disease, a violation in the system of calcium metabolism and hormones regulating it; in plasma increases the level of cholesterol, free fatty acids. From the early stages of the disease, the state of the enzyme systems of the liver changes. The function of the kidneys also does not remain intact - reduced daily diuresis, clearance by endogenous creatinine, excretion of electrolytes with urine. These deviations, apparently, are adaptive in nature.

[4], [5], [6], [7], [8]

Electrolyte causes of anorexia

When studying electrolyte balance in patients with different forms of anorexia nervosa, a drop in the level of potassium in plasma and cells, intracellular acidosis (although in plasma can take place as alkalosis - in patients with vomiting, and acidosis). Sudden death of patients with anorexia nervosa is associated with electrolyte changes at the cell level. The volume of circulating blood is reduced, but when calculated per 1 kg of body weight, there is hypervolemia (an increase of 46% compared with healthy). It becomes clear the need for cautious delivery of intravenous infusions to such patients. With this, the described cases of death are associated with improperly administered infusion therapy.

[9], [10], [11], [12], [13], [14]

Pathogenesis of anorexia nervosa

The basis of the disease are changes in the psyche with the formation of dysmorphophobic experiences, leading to a conscious refusal to eat, expressed weight loss. Chronic food insufficiency in many ways determines the clinical picture of the disease. The revealed violations of the secretion of gonadotropins, the delayed reaction of TSH on TRH, the change in secretion of STH and cortisol, which indicates the presence of a hypothalamic defect. With successful treatment of the disease and normalization of body weight, the disturbed secretion of hormones also normalizes, which indicates a secondary nature of disorders in the hypothalamus region with respect to weight loss. However, the frequent presence of certain neuro-exchange-endocrine syndromes in premorbid (obesity of the hypothalamic type, primary or secondary amenorrhea or oligomenorrhoea), as well as the preservation of amenorrhea in many patients even after complete normalization of body weight and preservation of the disturbance of the reaction of LH plasma to stimulation with clomiphene indicate a possible the constitutional inferiority of the hypothalamic-pituitary region, which takes part in the genesis of the disease. Differential diagnosis should be carried out with pathological conditions leading to primary and secondary hypopituitarism with pronounced weight loss. It is also necessary to exclude the primary endocrine and somatic pathology, accompanied by weight loss.