How far away are we from a cure for depression?
We are pretty far, unfortunately. This is, largely, due to the fact that depression is an extremely complex illness and we're still trying to figure out the "nuts and bolts" of the disorder.
Take something like Huntington's disease: it's caused by a single gene, and it's entirely genetic. Depression, on the other hand, is not entirely genetic. It has both genetic causes (studies using siblings/twins have shown there's about a ~40% rate of inheritance of depression) but also experience-dependent causes, primarily long-term stress (link, if you're interested:
http://www.mayoclinic.org/healthy-living/stress-management/expert-answers/stress/faq-20058233). Even the genetic causes are murky, because different parts of your brain do different things and have different patterns of genes to identify. To help clarify why this can be a big deal, one gene goes UP in the amygdala (controls fear/emotion) but DOWN in the prefrontal cortex (controls the stress response/some higher functions) in patients with depression. Considering that our genes are what dictate our biochemistry, that our biochemistry is altered in depression, and that drugs act by altering our biochemistry, understanding the genetics behind depression is a big deal.
In a nutshell, this is all important because to design treatments to cure depression we need to understand the biological basis for it. Until then, we might get lucky with some drug treatments (such as serotonin reuptake inhibitors), but we're kind of grasping blindly.
Part of the reason we're still so in the dark is because research on depression is SHIT compared to other illnesses. Forgive the rant, but it infuriates me that--despite the fact that depression is the #2 leading cause of disability worldwide (
Source) and the #1 leading cause of disability in people aged 14-44 (
Source) it is woefully underfunded. To give an example: depression is over a hundred times more prevalent than AIDS and, factoring in disability, results in eight times more years of life lost (
Source). In spite of this, it receives less than 12% of the funding that AIDS does.
Personal anger aside...I think it's important to keep several things in mind. The first is that biology is finally starting to implement computational approaches, and I think we're poised on the cusp of a golden age for medicine. What this computational approach means is that, instead of examining only one gene/cell/etc at a time, we're getting much more high-throughput methods. My own research, for instance, focuses on looking at how each of ~25,000 genes varies in the prefrontal cortex in depression--something that would have been unthinkable even ten years ago! So we should be getting much faster and more efficient at identifying the biological roots of depression and, hence, figuring out what to 'attack' in developing new treatment strategies. It sucks how slow science can be sometimes, but I think it's important to remember that we only discovered the structure of DNA--and that it carried genetic information--sixty years ago. Imagine what the next sixty will give us.
And, if I explained anything badly, please feel free to ask me to clarify.
