The mental breakdown patterns of a high-status white group and a low-status nonwhite group in Philadelphia were compared, the data being derived from records of all first admissions to Pennsylvania State Hospitals during a five-year period. The low-status group showed a significantly greater incidence of paranoid and other schizophrenic states, representing extreme aggression or withdrawal respectively. The authors attribute the difference to the group's impaired 'frustration tolerance' in the face of greater pressures and restrictions of the social environment than those affecting the high-status group. The latter present a higher incidence of organic brain syndrome due to cerebral arteriosclerosis; this difference 'cannot be explained by the group's greater longevity'.