Disinhibited social engagement disorder

Disinhibited Social Engagement Disorder (DSED), or Disinhibited Attachment Disorder, is an attachment disorder in which a child may actively approach and interact with unfamiliar adults. It can significantly impair young children’s abilities to relate with adults and peers, according to the "Diagnostic and Statistical Manual of Mental Disorders." Common examples include sitting on another person's lap or leaving with a stranger. 
DSED is exclusively a childhood disorder and is usually not diagnosed before the age of nine months or until after age five if symptoms do not appear. Infants and young children are at risk of developing DSED if they receive inconsistent or insufficient care from a primary caregiver.
Signs and symptoms.
The most common symptom is unusual interaction with strangers. A child with DSED shows no sign of fear or discomfort when talking to, touching, or accompanying an adult stranger. DSED can cause symptoms commonly associated with attention deficit hyperactivity disorder (ADHD) It can be comorbid with cognitive, language and speech delay.
Risk factors.
DSED is a result of inconsistent or absent primary caregivers in the first few years of childhood. Children who are institutionalized may receive inconsistent care or become isolated during hospitalization. Parental issues such as mental health problems, depression, personality disorder, absence, poverty, teen parenting, or substance abuse interfere with attachment. DSED "...may have a biological cause in some cases (e.g., Williams syndrome)."
Diagnosis.
The criteria for Disinhibited Social Engagement Disorder in the DSM-5 are:
A. A pattern of behavior in which a child actively approaches and interacts with unfamiliar adults and exhibits at least two of the following:
B. The behaviors in Criterion A are not limited to impulsivity (as in Attention-Deficit/Hyperactivity Disorder) but include socially disinhibited behavior.
C. The child has experienced insufficient care as evidenced by at least one of the following:
D. The care in Criterion C is presumed to be responsible for the disturbed behavior in Criterion A (e.g., the disturbances in Criterion A began following the pathogenic care in Criterion C).
E. The child has a developmental age of at least nine months.
Specifiers
It is considered persistent if the duration is more than 12 months.
It is considered severe if all the symptoms are present.
The ICD-10 definition is: "A particular pattern of abnormal social functioning that arises during the first five years of life and that tends to persist despite marked changes in environmental circumstances, e.g. diffuse, nonselectively focused attachment behavior, attention-seeking and indiscriminately friendly behavior, poorly modulated peer interactions; depending on circumstances, there may also be associated emotional or behavioral disturbance."
Differential diagnosis can be attention deficit hyperactivity disorder.
Treatment.
Two effective treatment approaches are play therapy and expressive therapy which help form attachment through multi-sensory means. Some therapy can be nonverbal.
Epidemiology.
The exact prevalence is unknown. In high-risk individuals, the prevalence rate is 20%.
History.
Disinhibited Social Engagement Disorder (DSM-5 313.89 (F94.2)) is the 2013 Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) name formerly listed as a sub-type of Reactive Attachment Disorder (RAD) called Disinhibited Attachment Disorder (DAD).
The American Psychiatric Association considers "...Disinhibited Social Engagement Disorder more closely resembles ADHD; it may occur in children who do not necessarily lack attachments and may have established or even secure attachments. The two disorders differ in other important ways, including correlates, course, and response to intervention, and for these reasons are considered separate disorders."