Because IPT was initially developed for the treatment of depression, its unique interpersonal approach was developed with the backdrop of important theoretical developments in the understanding of depression and the impact of interpersonal factors on this disorder. Interpersonal and object relations psychoanalytic approaches conceptualized depression as a fluid outgrowth of (dysfunctional) personality development. Sullivan himself related depression to repetitive patterns and internal vulnerabilities and rejected the depressed patient's attempts to tie the depression to a contemporaneous external event (Sullivan 1940). Cohen and colleagues (1954), of the interpersonal school, suggested that severe depression stems from having had a parent who resisted the child's move to independence and put excessive pressure on the child to achieve. They suggested that this led to dependency on the parent and alienation from peers, who were seen as competitors. Others (Fairbairn 1952; Klein 1935) theorized that depression results from early experiences of intense anger toward the frustrating but all-important internalized representation of the mother, and that this anger engendered feelings of ambivalence, guilt, helplessness, and ultimately depression.