Older men may father less intelligent kids

Children of older fathers perform less well in a range of cognitive tests during infancy and early childhood, a recent study has found.

Queensland Brain Institute researcher John McGrath analysed data about 33,437 children who were born between 1959 and 1965 in the United States.

Children were subject to cognitive testing at 8 months, 4 years and 7 years of age to measure the ability to think and reason, including concentration, learning, memory, speaking and reading skills.

The study found that the older the father, the more likely the child was to have lower scores on the various tests -– with the exception of one measure of physical coordination.

In contrast, the study found that children with older mothers gained higher scores in the same tests.

While previous researchers have suggested that older mothers may provide a more nurturing home environment, the Queensland Brain Institute study suggests that children of older fathers do not necessarily experience the same benefit.

McGrath and his colleagues hypothesise that the link between paternal age and a child's cognitive ability could be due to inferior sperm.

Unlike a woman's eggs, which are formed when she herself is in the womb, a man's sperm accumulates over his lifetime, which previous studies have suggested can mean increased incidence of mutations in the sperm at an older age.

More information is available from the research paper, which was published this week in PLoS Medicine.