A new study out of the Queensland Brain Institute in Brisbane, Australia suggests there may be a subtle decline in cognitive skills (intellectual activity as opposed to emotional response) among children whose fathers were near the age of 50 or older at the time of conception.
A review of over 33,000 children was undertaken at ages 8 months, 4 years and 7 years. Regardless of the mother’s age at conception, children whose fathers were 50 or older had slightly lower scores on all tests (concentration, memory, thinking, reasoning, reading, as well as motor tests). The findings were broadly consistent at all three ages. In contrast, advanced age of the mother was generally associated with better scores, using the same measures.
Other studies have suggested an association between paternal age and both autism and schizophrenia. A large Swedish study at the Karolinska Institute (published in the Archives of General Psychiatry, Sept. 2008) studied Swedish national registries for cases of bipolar disorder. They found, although small, a statistically increased risk of bipolar disorder in offspring as the fathers aged. (Findings applied to adult offspring only, not children.) The authors offered a possible biological explanation. Unlike women who are born with a complete supply of eggs that do not replicate, men are constantly replicating sperm. The older a man is, the more often his sperm cells have replicated, and the more replications, the greater the chance for random DNA copying errors to occur. While this is one interesting study, it is important to note that bipolar disorder is rare in any age group and that in the overall population, the vast majority of children of fathers of any age will not get bipolar disorder.
These are only two studies and much further research needs to be done to confirm any of these findings.