Interesting findings. If this holds true for humans, it seems possible that our use of antibacterial products, etc.may be contributing to the increase in ADHD.

New Comment
6 comments, sorted by Click to highlight new comments since:

Using measures of motor activity and anxiety-like behavior, we demonstrate that germ free (GF) mice display increased motor activity and reduced anxiety, compared with specific pathogen free (SPF) mice with a normal gut microbiota.

Are ADHD sufferers really less anxious than others? I would have said the opposite.

The Science Daily report on the article states

" The adult germ-free mice were observed to be more active and engaged in more 'risky' behavior than mice raised with normal microorganisms."

That's what made me think of ADHD, but I initially posted the link to the original research and the abstract doesn't mention the risky behavior. Children with ADHD are more active and take more risks. I think that's partially because many of them are less fearful and partially because they often act quickly, without thinking about consequences. Whether they are less anxious on average, I'm not sure. Often their difficulties focusing, poor social skills, etc. lead to negative consequences that can cause anxiety. The experiment was with mice, not humans- so it doesn't necessarily apply the same way. I definitely think this is worth more research.

Hang on a second - how are they controlling for effective calorie intake? Intestinal bacteria steal calories, and I would expect that to affect activity level, especially in mice.

The inferential distance between this study and linking antibiotics to ADHD in humans is huge. It's the wrong species; a few antibiotics aren't at all like being raised in sealed plastic and fed autoclaved food (and as far as I know the few people that do live in hermetically sealed environments don't develop ADHD more often than normal); and for that matter, higher activity level isn't the same thing as ADHD. Neither the original study nor the Science Daily article mention antibiotics or ADHD. Sorry mom, there isn't anything here to even raise it as a possibility, let alone meet the elevated standard of evidence required for making reliable conclusions about human behavior.

I didn't mention antibiotics, I said antibacterial products- I was referring to cleaners that kill all the bacteria on surfaces, thus altering what people are exposed to. Antibiotics do, also, alter the gut bacteria.

Yes, I am saying there may be links that the articles didn't mention. It's not just the higher activity level, but the increase in risky behavior.

Those are good points about effective calorie intake.

I would like to know how living in hermetically sealed environments have effected childrens' brain development. I've never seen anything published about that.

If antibacterial products contribute to ADHD, I doubt it's through that mechanism. The impact of antibacterial cleaners versus non-antibacterial cleaners on a person's overall exposure to bacteria is negligible. On the other hand, there's evidence that triclosan, the usual active ingredient in antibacterial soap, could be an endocrine disruptor.

Interesting, I didn't know that.