Maybe something as simple as gender roles no longer demanding that men be the sole provider in the family. This could cause men to consider other options instead of pursuing a college degree like they were expected to. Of course this would cause a growing number of men not attending college when compared to the past. Not to mention since women can now attend colleges (in hopes of actually pursuing a career and not just waiting to get married) there will of course be a growing number of women attending compared to the past.
I do have to acknowledge his idea that boys are being forced to take amphetamines in order to "keep up" in school. Most people at my school that were diagnosed with ADHD were male, and I don't think it is too much of a stereotype to say that boys in general run around more than girls do. However, I don't think this means society is experiencing a preference for women "norms".
But all of this is based on information I read, which doesn't mean it is accurate. If for some reason this this guys is right, then we would have a great example about how we rush through scientific advancement without putting as much effort into researching the consequences. Even if this isn't it, we will inevitably have it come bite our asses eventually.