A sublethal form, anaclitic depression was first described by René Spitz in the 1940s.

Spitz coined the term "anaclitic depression" to refer to partial emotional deprivation (the loss of a loved object).

Hospitalism (or anaclitic depression in its sublethal form) was a pediatric diagnosis used in the 1930s to describe infants who wasted away while in hospital.

Spitz valued several aspects: Infant observation and assessment, anaclitic depression (hospitalism), developmental transitions, the processes of effective communication, and understanding developmental complexity.