I was like that, always intellectual, many interests, and frequently depressed. This is hereditary, and at age 40 it really kicks in. I was going that way, and could have easily walked into the woods on a cold winter's day.
Luckily, I got the shock of my life from another family member with the same thing, and went to a psychiatrist. Amazing what a horrendous social stigma is attached to that act! The poor guy's only a doctor with extra experience in brain pills! No couch, just a crummy office.
I was cured by a simple pill. Really, it's just a nutrient deficiency in the brain. But Hollywood really screws it up. And the bizarre thing is that people in this state of mind will never seek help themselves. There should be a conclusive blood test that everybody over 40 gets, just like the finger up the bum! If it showed a prostate problem you would take the goddamn pill!
So, adopt a depressive today! Challenge them to take the pills for a while, just to see. Or try any other nasty trick you can think of. You may be saving a life.