Reactive attachment disorder
The broad theoretical framework for current versions of RAD is attachment theory, based on work conducted from the 1940s to the 1980s by John Bowlby, Mary Ainsworth and René Spitz. Attachment theory is a framework that employs psychological, ethological and evolutionary concepts to explain social behaviors typical of young children. Attachment theory focuses on the tendency of infants or children to "seek proximity" to a "particular attachment figure" (familiar caregiver), in situations of alarm or distress, behavior which appears to have survival value. This is known as a discriminatory or selective attachment. Subsequently, the child begins to use the caregiver as a base of security from which to explore the environment, returning periodically to the familiar person. Attachment is not the same as love and/or affection although they are often associated. Attachment and attachment behaviors tend to develop between the ages of six months and three years. Infants become attached to adults who are sensitive and responsive in social interactions with the infant, and who remain as consistent caregivers for some time. Caregiver responses lead to the development of patterns of attachment, that in turn lead to internal working models which will guide the individual's feelings, thoughts, and expectations in later relationships. For a diagnosis of reactive attachment disorder, the child's history and atypical social behavior must suggest the absence of formation of a discriminatory or selective attachment.
Diathesis–stress model
The use of the term "diathesis" in medicine and in the specialty of psychiatry dates back to the 1800s; however, the diathesis–stress model was not introduced and used to describe the development of psychopathology until it was applied to explaining schizophrenia in the 1960s by Paul Meehl.
The diathesis–stress model is used in many fields of psychology, specifically for studying the development of psychopathology. It is useful for the purposes of understanding the interplay of nature and nurture in the susceptibility to psychological disorders throughout the lifespan. Diathesis–stress models can also assist in determining who will develop a disorder and who will not. For example, in the context of depression, the diathesis–stress model can help explain why Person A may become depressed while Person B does not, even when exposed to the same stressors. More recently, the diathesis–stress model has been used to explain why some individuals are more at risk for developing a disorder than others. For example, children who have a family history of depression are generally more vulnerable to developing a depressive disorder themselves. A child who has a family history of depression and who has been exposed to a particular stressor, such as exclusion or rejection by his or her peers, would be more likely to develop depression than a child with a family history of depression that has an otherwise positive social network of peers.