New Information On Autism and Schizophrenia

We've always been told that the age of the mother affects the unborn child.  Specifically, that older mothers have a greater chance of random mutations, thus a greater chance for a variety abnormalities.  Well, a new study finds that older men are more likely to father a child who develops autism or schizophrenia.  The age of the mother has no bearing on the risk for these disorders.  The overall risk to a man in his 40's or older is in the range of 2% at most, so it is hardly a reason to forgo fatherhood in older men.  This study supports the argument that the surging rate of autism diagnoses over recent decades is attributable in part to the increasing average age of fathers.  This could account for as much as 20-30% of the cases. 

The findings also negate the  long held assumption that the age of the mother is the most important factor in determining the odds of a child having developmental problems.  The risk of chromosomal abnormalitites, like Down syndrome, increase for older mothers, but when it comes to the more complex psychiatric and developmental issues, the bulk of the genetic risk originates in the sperm, not the egg.

This study was was led by the Icelandic firm Decode Genetics, and it analyzed genetic material taken from blood samples of 78 parent-child trios, focusing on families in which parents with no signs of mental disorder gave birth to a child who developed autism or schizophrenia.  The research team found that the average child born to a 20-year-old father had 25 random mutations that could be traced to paternal genetic material.  That number increased steadily by two mutations a year, reaching 65 mutations by the time men reached 40. 

This information by itself hardly explains the overall increase in autism diagnoses.  The birthrate of fathers age 40 or older has increased by more that 30% since 1980, but the diagnosis rate of autism has increased  tenfold, to 1 in 88 8-year-olds.

If these findings hold up and extend to other brain disorders, we may soon be collecting the sperm of young adult men and cold storing it for later use, just as we already do with the eggs of young women.