A great idea in a petri dish on rat tissue, but I think we'll find that neurogenesis or the lack thereof in live human patients is a little more complicated than that.
I do agree people who have abused drugs should be taking a few ius of GH daily, but I also think there are some other things to think about.
Neurogenesis in the hippocampus and the amygdala is largely regulated by BDNF and GDNF, long-story-short this is like igf-1 for nerve cells. Drugs like opiates put a stop to all that neurogenesis through a few pathways, but cortisol is a main offender here. The takeaway message wouldn't be to just turn off cortisol, but instead to use drugs that have been shown to reduce cortisol's effect on dampering GDNF and BDNF in those regions of the brain. Tianeptine is one such drug. Royal Jelly shows a lot of promise too.
The other thing to consider is that we need to rewire the brains pleasure centers again. They've gotten all fucked up from overuse. Unlike Androgen receptors, Dopamine receptors and Opiate receptors lose their density, so they run away and tuck up to keep from getting overstimulated. When the user stops using the drugs, those pleasure buttons never get fully restored.
There are some interesting things going on right now in that field of research and I hope that GH can help accelerate their efforts to get people's brains back together.
For those interested, there is a lot of cool things happening with Ibogaine and a lesser known option, Salvia Divinorum, which agonizes the Dynorphin receptors of the opiate system, which essentially restores dopamine density in the brain. There are some people who have been using it for exactly this purpose with great success.