I was taking Mucuna (a natural source of levodopa) until I found out that it increases melanin production, which totally makes sense when you think about it, but it's not recommended if you're at risk of melanoma. If you don't, then L-DOPA works great in preventing myopia as well.
"Levodopa" sounds like a Harry Potter spell. The abstract says "the role of dopamine in modulating executive function, working memory and associative learning has been established", I wonder if there are side effects to mucking with your brain chemistry in this way.
For the curious, they're referring to L-dopa.<p><a href="http://en.m.wikipedia.org/wiki/L-DOPA" rel="nofollow">http://en.m.wikipedia.org/wiki/L-DOPA</a>