Wednesday, September 3, 2008
The press was all over a recent study in the Archives of General Psychiatry linking bipolar disorder to the older fathers. The cause is unknown but it may have something to due to getting mutated sperm as we get older (not unlike what happens as this laptop barbecues my scrotum after about a half hour of use). Children born to these dads were 37 percent more likely to develop bipolar disorder than those born to men in their 20s. That was the sound bite that got spit out by radio stations all over the country. The problem with this information is that it is fragmented. Let's say, for example, there are two case of Cowabunga Disease (made that up) for every million people. Now let's say that it was found that for every million readers of the Placebo Journal there are three cases of Cowabunga Disease. That would mean a 50% increase in this disease just by reading PJ. Sounds bad but the absolute number is so small it is still a very small risk. In fact, it’s a statistical nightmare. After looking at over 7.7 million patients discharged from a hospital, they whittled the numbers down to find a little over 13,000 cases of people with definitive bipolar disorder. They then broke these 13K down to the ages of their fathers when they had them. For a control group, they took five times the amount of bipolar patients or around 67,000 normal patients who were discharged and found the ages of their fathers when they had them. Got it? Anyway, the reference group, as they call it, is the patients whose fathers were between the ages of 20 and 24 when they helped in the conception process. They found 1774 patients with bipolar disorder at that age and 10090 of regular patients. For those who had dads over the age of 55, there was grand total of 68 patients who had the bipolar disorder and 256 who did not. Only 68 patients!!! I guess because that ratio is higher than the reference ratio these authors were able to get some statistical significance and publish this study. Only 68 patients out of 13,000 or so with bipolar disorder. Only 68 patients out of the more than 7 million investigated. You have got to be kidding me.
Posted by Authentic Medicine Blog at 5:10 AM