What does advanced paternal age have to do with non-familial schizophrenia?

Answer 1

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It is thought that causal factors can initially come together in early neurodevelopment, including during pregnancy, to increase the risk of later developing schizophrenia. One curious finding is that people diagnosed with schizophrenia are more likely to have been born in winter or spring[33] (at least in the northern hemisphere). However, the effect is not large. Some researchers postulate that the correlation is due to viral infections during the third trimester (4-6 months) of pregnancy. There is now significant evidence that prenatal exposure to infections increases the risk for developing schizophrenia later in life, providing additional evidence for a link between in utero developmental pathology and risk of developing the condition.[34]

A study by Sweden's Karolinska Institute and Bristol University in the UK, looked at the medical records of over 700,000 people and calculated that 15.5% of cases of schizophrenia seen in the group may have been due to the patient having a father who was aged over 30 years at their birth, the researchers argue this is due to build up of mutations in the sperm of elder fathers.[23]

Women who were pregnant during the Dutch famine of 1944, where many people were close to starvation, had a higher chance of having a child who would later develop schizophrenia.[35] Similarly, studies of Finnish mothers who were pregnant when they found out that their husbands had been killed during the Winter War of 1939–1940 have shown that their children were much more likely to develop schizophrenia when compared with mothers who found out about their husbands' death after pregnancy,[36] suggesting that even psychological trauma in the mother may have an effect.
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