Paternal and maternal age as risk factors for psychosis: findings from Denmark, Sweden and Australia

Maternal household crowding during pregnancy and the offspring's risk of schizophrenia

“…While offspring whose mothers resided in a household with 5 or more inhabitants had 47% higher risk to developed schizophrenia (compared to those who resided with 4 or less), this finding was explained primarily by the impact of the paternal age. These results are consistent with the growing literature demonstrating the significant impact of paternal age on the offspring's risk of schizophrenia (Tsuchiya et al, 2005;Sipos et al, 2004;El-Saadi et al, 2004;Zammit et al, 2003;Byrne et al, 2003;Dalman and Allebeck, 2002;Brown et al, 2002). The number of rooms in the mother's household during pregnancy and the household crowding per se did not have a significant impact on the offspring's risk to develop schizophrenia.…”

Influence of Paternal Age in Schizophrenia

“…Cette hypothèse est corroborée par plusieurs études montrant que l"âge moyen du père dans les formes sporadiques est plus élevé que dans les formes familiales [19], même si ces résultats ne sont pas toujours confirmés [7,38,42].…”

“…Les différentes études vont toutes dans le sens d"une augmentation du risque avec l"augmentation de l"âge du père à la naissance, même si elles utilisent des méthodologies différentes. [3,7,34]. Seules l"étude cas-témoin australienne d"El Saadi et al, [7] et l"étude de Torrey et al, [37] ne retrouvent pas d"augmentation du risque en fonction de l"âge du père, probablement du fait d"un manque de puissance statistique.…”

Impact of Epidemiology on Molecular Genetics of Schizophrenia

“…Large-sampled cohort studies in Israel, Sweden and Denmark show that the mean age of parents in the general population is ~ 28 years for mothers and ~31 years for fathers; the mean age of both parents is < 29.6 years (Malaspina et al, 2001;El-Saadi et al, 2004). Therefore we assume here: 64 4 29.6 10 10 1.48 10 20…”

“…Some researchers have proposed the hypothesis that schizophrenia is associated with de novo mutations arising in paternal germ cells (Malaspina et al, 2001;Zammit et al, 2003;Byrne et al, 2003;El-Saadi et al, 2004;Sipos et al, 2004). It is based on the observation ('paternal age effect') that the risk of schizophrenia in the offspring seems to increase as the paternal age advances from 20 years to over 50 years.…”