A review and reanalysis of Bruno Schulz's "Erkrankungsalter schizophrener Eltern und Kinder [Age at onset of illness in schizophrenic parents and offspring]:" Zeitschrift für die gesamte Neurologie und Psychiatrie, 168, 709-721, 1940

Abstract

Nearly all previous evidence of the familial transmission of age at onset of schizophrenia has been in siblings and twins. In his paper, Bruno Schulz examined the age at onset distribution of schizophrenia in affected parent and offspring pairs, using a systematic series of ascertained cases (n = 106), as well as a second series of chronic in-patients (n = 36). The parent-offspring correlation in age at onset, for cases with a definite diagnosis in the systematically ascertained series, was estimated at 0.346 (95% confidence interval 0.134, 0.528). Schulz did not test for differences between the two series and between males and females, but our reanalysis, using correlational methods and a mixed linear model, did not detect any significant differences. These results are consistent with previous findings that age at onset of schizophrenia is influenced by familial factors which may be genetic.