I have a theory: Theories are like assholes. Hold it... that would be an axiom.
A Theory: teenage depression is a necessary stage of development in the transformation from child to adult.
When I was a kid, I promised myself I would remember what it was like to be a kid, and how I was going to be the coolest adult ever. However, I recently realised that, despite my efforts, I have become an adult, complete with worries about money, getting the oil changed, making sure there's food in the house, clean clothes and all that boring stuff.
I was watching a couple of one-year olds at a party a while back, and they definitely had an us/them outlook on life. I clearly fell into the category of "them".
Now consider the process that most teenagers go through. During puberty your body is going through thousands of chemical changes, and part of the result is a general malaise, moodiness, and perhaps symptoms that in an adult would be diagnosed as mild depression.
You've been there, I've been there… after all, we're grown-ups now.
Whether simply instigated by chemical changes during puberty, or precipitated by the experiences of puberty — self-discovery, first love, cliques, social pressures to conform in the present while figuring out a future — it seems adolescence is a minefield of triggers for depression.
KEY: I recently learned that one of the side-effects of depression is its effects on memory. Depression can cause gaps in your memory that you can track-back.
What if the tumultuous era of teenage-hood is designed to help your mind wipe the strong feelings of what it is like to be a child?
I can distinctly remember that there is some feeling that comes with being a child.
One example: As a child, you feel free to approach another child within your general age range when in a large group. At malls, airports, playgrounds, wherever two kids meet, they instantly seem to want to form a friendship.
As an adult, there seems to be greater social barriers to talk to strangers. There's just so damn many of them.
Just try to childhood approach of walking up to a complete stranger your own age and saying "Hi! Whatcha doin?"
To make things manageable, we create sub-groups: adults with kids, single adults, gay adults, yoga-practicing adults, adults with tattoos and harleys. We'll latch on to some item we may share with a person in order to categorize them in a group. As a kid it seems more possible to have the us kids/them adults mentality, with the age range rather broad on the underside of puberty.
I know I'm digressing on my point, but allow me to ramble... as a teenager, you're part of an even smaller sub-group. Consider you spend 12 to 13 years as a "kid", seven years as a teenager, and around 40 to 65 years as an adult. Percentage-wise, you wind up in a smaller, more segmented and isolated group as a teenager... another factor that can possibly add to the tendency toward depression.
Those younger than you are boring and tedious. Those older than you can't be trusted.
The seven or so years you spend as a teenager acclimatizes you to the smaller sub-groups you'll encounter as an adult. Yes, when you enter your early 20's often you're in a post-teenage environment due to university or college. However, it is not unusual for 20 year olds to move straight into the work world and mix with the sub-groups of adults.
The possibility of remaining within the teenage years can be self-directed to a certain extent. However, the damage is done by the time you're graduating from high-school... you don't know what it's like to be a kid anymore: the trials of the teenage years have wiped the feeling from your memory. You may remember logically what it's like. You may empathize. But you don't "feel" it anymore.
So, for teenage-stage depression, perhaps it is designed explicitly to re-program the brain. From an evolutionary point of view, it would make sense that you retain some small part of knowing what it is like to be a child, but to no longer strongly identify with the role.
Some understanding allows you to relate to your children. But were you to still have the true understanding of what it is to be a child... to feel it and know it in your heart, to be a child to the soul, you would be unable to discipline the child, to direct their life so that they reach teenage-hood and go through the same shit you did.
More importantly, you'd be unable to direct the child within yourself to achieve great things.
The depression partially wipes that sense of "childhood" from our memory, so we will make the "right choices" socially for both ourselves and our progeny.
Otherwise we'd be a society of adults eating fast food every day, calling in sick to play hooky, and using all the money we make to buy ourselves toys.