I'll be honest. When I was younger, all my friends (I refuse to include myself) smoked a lot of pot and (thanks to it being a gateway) other drugs. Now that we're all grown up and reliable adults, every last one has at least one autistic child. Coincidence? Certainly autism rates have skyrocketed. My theory? Recreational drug use.
They're also all suffering from conditions at a higher rate than the national average (everything from sleep apnea to strokes to autoimmune). Better diagnosis? No, probably the drugs again. The problem is that simply not enough studies have been done to properly analyze the long-term effects of drugs.
As I'm a scientist and can see 15+ years after the fact now, I can tell you it's pretty obvious. If I could only go back in time...and trust me when I say my friends feel the same. Now they add in a far higher than average cost to the medical system because they wanted to "just smoke a little weed."