Meh, this is just pro-pharma propaganda. Dozens of drugs increase brain plasticity, but you don't hear Eli Lilly funding journal articles saying that everyone should smoke weed or drop acid in combination with therapy. What exactly is so special about Prozac? Absolutely nothing.
It's not the Prozac that's the key in the study, despite the Scientific American angle:
What's significant here is that they were able to study the plasticity directly, and found that the reduced anxiety depended both on the Prozac (insert your favorite chemical here) and the re-training. And it compares it to a physiological difference in the two cases. That's novel, regardless of the drug. Prozac is a natural choice 1) because it's well studied, and 2) it has the well-documented clinical property of working best when combined with treatment (edit: therapy treatment).
How does this happen? Addressing this latter question is exactly what makes the study so cool: they identified physiological mechanisms that might cause this behavior, pending further research. Sure, they could ask the same questions with weed, or acid, or mushrooms, or caffeine. They happened to use Prozac.
Disclaimer: I do neuroscience, but not in this field.
