Anorexia nervosa usually starts in late adolescence and is about 20 times more common in girls than in boys. This disorder is characterized by a failure to maintain normal body weight for an individual’s age and height; weight loss is at least 15 percent of the ideal body weight. Weight loss occurs because of an intense desire to be thin, a fear of gaining weight, or a disturbance in the way in which the individual sees her body weight or shape. Postmenarchal females with anorexia nervosa usually experience amenorrhea (i.e., the absence of at least three consecutive menstrual periods). Medical complications of anorexia nervosa can be life-threatening.

The condition appears to start with an individual’s voluntary control of food intake in response to social pressures such as peer conformity. The disorder is exacerbated by troubled relations within the family. It is much more common in developed, wealthy societies and in girls of higher socioeconomic class. Treatment includes persuading the person to accept and cooperate with medical therapy, achieving weight gain, and helping the person maintain weight by psychological and social therapy.

Bulimia nervosa is characterized by excessive overeating binges combined with inappropriate methods of stopping weight gain such as self-induced vomiting or the use of laxatives or diuretics.

Other childhood disorders

Stereotyped movement disorders involve the exhibition of tics in differing patterns. A tic is an involuntary, purposeless jerking movement of a group of muscles or the involuntary production of noises or words. Tics may affect the face, head, and neck or, less commonly, the limbs or trunk. Tourette syndrome is typified by multiple tics and involuntary vocalization, which sometimes includes the uttering of obscenities.

Other physical symptoms that are often listed among psychiatric disorders of childhood include stuttering, enuresis (the repeated involuntary emptying of urine from the bladder during the day or night), encopresis (the repeated voiding of feces into inappropriate places), sleepwalking, and night terror. These symptoms are not necessarily evidence of emotional disturbance or of some other mental illness. Behavioral methods of treatment are usually effective.

Factitious disorders

Factitious disorders are characterized by physical or psychological symptoms that are voluntarily self-induced; they are distinguished from conversion disorder, in which the physical symptoms are produced unconsciously. In factitious disorders, although the person’s attempts to create or exacerbate the symptoms of an illness are voluntary, such behavior is neurotic in that the individual is unable to refrain from it—i.e., the person’s goals, whatever they may be, are involuntarily adopted. In malingering, by contrast, the person stimulates or exaggerates an illness or disability to obtain some kind of discernible personal gain or to avoid an unpleasant situation; e.g., a prison inmate may simulate madness to obtain more-comfortable living conditions. It is important to recognize factitious disorders as evidence of psychological disturbance.

Impulse-control disorders

Persons with these conditions demonstrate a failure to resist desires, impulses, or temptations to perform an act that is harmful to themselves or to others. The individual experiences a feeling of tension before committing the act and a feeling of release or gratification upon completing it. The behaviors involved include pathological gambling, pathological setting of fires (pyromania), pathological stealing (kleptomania), and recurrent pulling of hair (trichotillomania).

Adjustment disorders

These are conditions in which there is an inappropriate reaction to an external stress occurring within three months of the stress. The symptoms may be out of proportion to the degree of stress, or they may be maladaptive in the sense that they prevent an individual from coping adequately in normal social or occupational settings. These disorders are often associated with other mood or anxiety disorders.