let us count the ways the study could be wrong.
Selective reporting? Self reporting is notoriously wrong, because people just don't remember stuff...Moms whose kids have problems (be it ADHD or congenital abnormalities) try to think if they caused it. Give them a questionaire suggesting they took tylenol, and they think: OH HORRORS I DID.
2: No dose or trimester correlation.
researchers found that kids whose mothers took the painkiller at any point during pregnancy were 29% more likely to be diagnosed with ADHD
so did mom take one near term for a backache, or does she have migraine or chronic headaches and take six or eight a day every day, including many doses in the first trimester?
Without a dose/disease/trimester correlation, the study is useless.
3: How did they diagnose ADHD?
Yes, it is a real disease, but like most mental diseases, it's a continuum not a diagnosis, so where you draw the line can result in an "epidemic", be it autism or ADHD or paranoia (see this lecture at Gresham college on the problem)
did they take the paracetamol for a fever? Viruses can cause fetal malformations, and some viruses or other infections could cause ADHD (e.g. did she clean the cat litter, get toxoplasmosis, think it was the flu and treated it with tyleonol, but her kid got congenital toxoplasmosis)?
Did they take paracetamol for a hangover? Fetal alcohol syndrome is associated with ADHD.
Were the moms whose kids had ADHD older than the other moms? A 36 year old might be more prone to aches and pains, and also more prone to mild toxemia or age related arthritis etc. that make her more prone to take a pain pill.
There were 64,000 women in the study, and the diagnosis increase was 27%. But what are the absolute numbers?
I say this because all the hype about "statins" in lowering heart attack rates are impressive, until you note that statistics are impressive, but not the absolute numbers. (i.e. 20 vs 24 cases out of 100 thousand). So how many cases are we talking about here?
Was there publishing bias?
Members of the research team had long suspected that acetaminophen may behave as an endocrine-disrupting chemical capable of influencing fetal brain development, said Dr. Beate Ritz, chair of the department of epidemiology at UCLA's Fielding School of Public Health and one of the study's senior authors.
yup. Seek and ye shall find.
like this comment:
some studies have found higher rates of male babies with undescended testicles born to women who took it during pregnancy.
translation:" Some studies" means that some studies showed it and some didn't.
supposedly they checked for this by a long study where docs asked the moms all these questions and tracked the kids, diagnosing them by if they took medicine for ADHD.
The international research team, led by Dr. J¿¿rn Olsen, an epidemiologist at the University of Aarhus in Denmark, tracked the study's pediatric subjects from their first trimester of gestation for as long as 15 years. In addition to surveying parents about their children's behavior, they tapped into Denmark's comprehensive and reliable registries of physician diagnoses and dispensed pharmacy prescriptions to glean an accurate measure of ADHD in the population.
The study design averted a problem known as "recall bias" by gathering details on acetaminophen use long before signs of ADHD would become evident. Researchers did not ask pregnant subjects to detail how much or how often they took acetaminophen, but they interviewed them at the end of every trimester to gauge their use of the analgesic. That allowed the team to discern that the timing of a woman's acetaminophen use is likely to be important to fetal brain development.
Big Brother is watching you.
Overall, about 55% of the mothers took acetaminophen at some point during their pregnancy, the researchers found. Based on parents' assessments of their children's emotional, social and learning strengths and weaknesses over a six-month period, the baseline incidence of ADHD-like behaviors in children who weren't exposed to acetaminophen in utero was about 2.5%. Among those who used the medication at some point during pregnancy, the rate was 3.4%.
in other words, a one percent difference.
now tell us how many smoked, how many drank alcohol, how many took cocaine, and how many were so obsessive compulsive that they actually told you the truth.