Nostalgia: a 'forgotten' psychological disorder.

Nostalgia, a psychopathological condition affecting individuals who are uprooted, whose social contacts are fragmented, who are isolated and who feel totally frustrated and alienated, was first described in the 17th century and was a problem of considerable interest to physicians in the 18th and 19th centuries. By the 20th century it seemed to have disappeared, but reappeared under other labels.