The late Richard Gardner was the psychiatrist that came up with the controversial "Parental Alienation Syndrome." He regarded it as a condition in which children are obsessed with criticism of a parent that is often unjustified and/or exaggerated. A parent will "brainwash" the child meaning that the parent is "deliberately bring[ing] about the alienation of the child from the other parent" and it occurs in a very obvious manner. There becomes the sense of a "loved" parent versus a "hated" parent. Another important factor is the contributions the child makes on their own to the denigration of the "hated" parent that is uninfluenced by the "loved" parent (Gardner, 1985) Dr. Douglass Darnall (1999) clarifies the difference between "parental alienation" and "Parental Alienation Syndrome" by saying that parental alienation focuses on the parents' behavior, while Parental Alienation Syndrome focuses on the child's behavior and their unjustifiable denigration towards the target parent.
"Parental Alienation Syndrome," however, has been a controversial topic for psychologists since the term was created. Since it is different than parental alienation itself, it has been sought after by many to be included in the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, that was published on May 27, 2013. Vice chair of the DSM task force was quoted as saying back in 2010,
"There is not sufficient scientific evidence to warrant its inclusion in the DSM" and said that there is a "slim" chance that it would be placed in the DSM-5 (Crary). That prediction came true, and it is not included in the DSM-5.
References:
Crary, David. "Psychiatric experts assess parental alienation."
Washington Times. Oct 2010.
Darnall, Douglass. "Parental Alienation: Not in the Best Interest of the Children." North Dakota Law Review, Volume 75, 1999, p 323-364.
Gardner, R. A. "Recent Trends in Divorce and Custody Litigation." Academy Forum, Volume 29, Number 2, 1985, p. 3-7.New York: The American Academy of Psychoanalysis.
Herold, Conners, & Moore. "American Psychiatric Association Board of Trustees Approves DSM-5: Diagnostic manual passes major milestone before May 2013 publication." American Psychiatric Association. Dec 2012.
