Relationship between sex differences in onset of schizophrenia and puberty

Some neurodevelopmental hypotheses of schizophrenia have postulated that sex differences in onset of illness could be explained by sexual dimorphism in onset of puberty, suggesting that early maturation accounts for the later onset of illness in women. The objective of this study was to analyse the relationship between age of menarche and age of onset of schizophrenia in a sample of Chilean patients. The medical records of 105 schizophrenic women diagnosed according to DSM-III-R criteria were studied. In all cases age of onset (first psychotic symptoms) and age of menarche were obtained. Pearson's correlation and student's t-test were used to analyse the data. The mean age of menarche in the sample of female patients (12. 98 years, S.D.=1.49) was significantly different from that of the general population of Santiago, Chile (12.53 years, S.D.=1.32) (t=2. 38; P<0.05). The mean age of onset of schizophrenia in female patients (19.92 years, S.D.=5.13) was significantly earlier in the Chilean sample than that reported in European and North American samples (P<0.05). No differences were observed when comparing the mean age at menarche. The subtypes with the earliest onset presented the earliest age of menarche and the subtypes with the latest onsets showed the latest ages at menarche. However, no correlation was observed between the age at onset of illness and the age at menarche, both in the total sample and in the analysis by subtype. The results of this study do not support a correlation between puberty and age of onset of illness.