A study in the journal Bipolar Disorders two weeks ago found that the children of fathers 50 or older had three times the risk of having bipolar disorder compared to children of fathers 30-34 years old.
Bipolar disorder afflicts about 1 percent of the general population, so, in very rough terms, the risk of bipolar disorder in the children of these older fathers is about 3 percent.
That's about one in every school classroom with 30 kids. it sounds frightening.
But turn it around and put it this way: The children of those older fathers have a 97 percent chance of not having bipolar disorder. Suddenly, the risk sounds quite different.
It's not easy to convey these risks properly to readers, and reporters often get it wrong.
In another study this week on older fathers, researchers found stunningly higher risks associated with the children of older fathers. The study, in JAMA Psychiatry, found that the children of fathers 45 and over had 25 times the risk of bipolar disorder compared to the children of fathers 20-24. They also had 13 times the risk of ADHD and 3-1/2 times the risk of autism.
How does one report that without terrifying parents and potential parents?
Ian Sample in The Guardian solved the problem -- or tried to -- by burying the numbers low in the story. In his lede, he wrote that children of older fathers "are at greater risk of developing psychiatric problems and more likely to struggle at school." That's accurate, but incomplete. In the fourth graf -- we've still seen no numbers -- he quotes the lead author of the study saying that he and his colleagues "were shocked when we saw the comparisons." The comparisons were indeed shocking, but Sample's readers must have been puzzled by the quote, because they hadn't yet been given the shocking numbers.
He doesn't report them until halfway through the story, and even there he is unable to report numbers for the bipolar risk. Rather than saying it was 25 times higher in the older fathers, he reports that the risk was less than 1 percent in the children of the younger fathers and about 14 percent in the children of the older fathers. As a rule, reporting absolute risks is a good idea, but in this case I think it's important to report absolute and relative risks, because the relative risks are just too important and dramatic to ignore.
The Associated Press did the same thing. It put the numbers in the middle of its story. Benedict Carey of the New York Times put the figures for bipolar disorder and ADHD -- the biggest and most impressive numbers in the study -- in the second to last paragraph.
I don't understand this; the numbers are far higher than what's been found in other studies, and they should be prominently featured near the top of every story.
William Hudson at CNN put the numbers in the third graf, although he made a rounding error on the bipolar disorder risk, writing 24 instead of 25 (the figure in the study was 24.70). Ryan Jaslow at CBS News also put the numbers in the third graf. LiveScience put the numbers in the fourth graf and made the same rounding error with bipolar disorder.
I happen to have a horse in this race myself. I posted on the study for TODAY.com, where I was asked to use a first-person lede. But if you look at the story, you will see that when I turned to the news (after three grafs of personal material), I put the numbers in the second graf. If this had been a straight news story, I would have put them in the lede--at least some of them, and especially the relative risk for bipolar disorder.
And about that biological clock: We've known for decades that the children of older mothers face higher risks, especially a higher risk of Down syndrome. That has put extreme pressure on some women to make difficult decisions about careers and childbearing. Men, it seemed, were somehow exempt from that painful decision. They could have children at any age.
So it might come as a relief to some women that they are not alone with respect to these difficult decisions. But is that reason to cheer?
Apparently so for Sally Peck at The Telegraph, who has used the study to "gleefully" pose some questions about biological clocks. She wonders whether the new study will "open up the testicular sack" to scrutiny, and whether men will "be accused of 'accidentally' impregnating people on purpose just because that crucial 45th birthday is staring them in the face?"
We're talking about what seem to be sharply increased risks for ADHD, autism and bipolar disorder, among others. How funny is that?
Perhaps we should introduce Peck to the older father of a seriously ill child, and let her pose some gleeful questions to him.
(This post originally appeared at the Knight Science Journalism Tracker.)