Scandinavian psychiatrists have been pre-eminent in elucidating the concept of reactive psychoses. This diagnosis has never found much acceptance except in Scandinavia, and the new Diagnostic and Statistical Manual of Mental Disorders, 3rd Edition category of brief reactive psychosis is quite different from reactive psychosis as described by most Scandinavian clinicians and researchers. The concept of psychogenic psychoses is, however, not new. Indeed, many psychiatrists of the early 20th century stressed the psychogenic factors in psychotic mental disturbances. Reactive psychoses have generally been considered illnesses distinct not only from schizophrenia but also from manic-depressive psychosis with a distinctive genetic component. Of 283 hospitalized patients at Johns Hopkins for whom long-term follow-ups were available and of whom all were first admissions, Astrup retrospectively diagnosed 91 as reactive psychoses. A contrasting group of 78 "systematic schizophrenics" by Leonhardt's criteria were identified. Stephens found that these two groups differed significantly in that the reactive patients had a) a more acute onset, b) more precipitating stress, c) more affective symptoms, d) more confusion, e) less affective blunting, f) a better premorbid adjustment, g) less premorbid schizoid traits, h) fewer schizophrenic relatives, and i) a much more favorable long term outcome.