Define cure I guess. There are already treatments showing more promise than SSRIs, but I'm not sure how effective they'll end up being. I suppose I'd expect this once we get a better handle on them, and how to treat them. Someone mentioned nanomedicine, which is a decent idea but I'm honestly unsure what breakthrough would do this. I'd probably still say I expect it within a couple decades, due to the integration of AI into R&D gradually speeding up progress into the singularity, but medical advancement tends to be delayed due to testing/approval (to be clear, this is why I say a couple decades, rather than one).