Depression is indeed a call to attention, instigated by our deep (unconscious) minds.

There are probably many ways to successfully treat the symptom of, or outright cure, depression (medication to achieve the right neurochemical balance being one of them), but the two most opportunistic approaches (allowing us to get the most out of the experience), as I see it, are the following:

1.) Be with the depression, or even deeper than it if we can manage, allowing it to do whatever it does, even if that means growing symptoms. Let it be what it is without labeling it, condemning it, or trying in any way to resist it.

This is a deep spiritual approach that may ultimately lead to an ego-death - a total resolution to the ongoing identity search (crisis). This approach has big risks (the possibility of experiencing growing depression to the point of becoming suicidal/ becoming more and more desensitized to the world/ feeling more alienated from people/ the possibility of diverting into paranoid delusions somewhere along the line), but also huge rewards (freedom from unnecessary psychological suffering that's created by conditioned beliefs and inherited patterns of thought).

Because the risks are so high and the right path is so undefined, it's probably best to have the help of someone who's had experience with dealing through depression in this way - to its perfect resolution. This person absolutely must be a trusted authority; someone who provides us with ample evidence that they know the inside and outside of it and whom convinces us that he/she can be trusted with our health.

2.) Take the empowered - me approach, asserting a strong ego (identity) by affirming to ourselves that we have the energy and power to fulfill our desires, or uncover them (should we sense that we don't know what it is that we want or are apathetic about discovering this). This we can all achieve. One useful approach is to simply reminding ourselves that: "this is a new day...as fine of a day as any to be re-born." (a reminder that we don't have to hold onto the baggage of the past, which may create that spark, or inspiration, to make a healthy and positive change that we've been so desperately needing).

Risks include becoming egotistical (self-centered)/ delusional and/or unwittingly masking the depression even more (consciously believing that we're overcoming the depression but unconsciously knowing that we're only suppressing it and allowing it to grow and physically manifest in many different ways - self-sabotage).

The pay-off can be a total transformation into an every way new and improved version of ourselves, who has the energy, willingness, and self-belief(s) required to make the most of our lives.

In either of the above approaches, our ability, or inability, to achieve, and maintain, a state of deep self-awareness (deeply aware of one's own conscious processes and relentlessly honest with oneself about what is seen) is the biggest factor to finding a beneficial resolution. As such, it's really the most important point to keep in mind, IMO.

Also, if either of the two above approaches don't yield fruits within six months to a year, then a new approach is likely warranted. Perhaps medication or psychotherapy will provide answers.