[Note: This article is highly speculative, and I will pull it down without warning if I find evidence to the contrary]
Reading very many of Scott Alexander blogposts, which review basic neuroscience research, has given me the impression that PTSD and depression might be a fundamental neuroscience problem. Let me explain that below.
What does PTSD feel like, exactly? You had a bad experience a gazillion years ago. Maybe you were bullied, or had a bad breakup, etc. You wake up in the morning, and suddenly that is all you can think about. How this bad experience will keep affecting your future, how there is no escape, how you wish you could have behaved differently back then, etc.
This is your brain going in a downward spiral, sucking you into a pit of misery. Well a part of your brain anyway. Reading Alexander’s posts give you the clear impression that your brain is not one cohesive entity. It is a bunch of different shit thrown together. And there is a part of the brain that is responsible for computation and logical inferences from known data. And this part of the brain is not engaged when you go into this downward spiral.
Imagine that you’re falling deeper and deeper into a well. You can stop this fall at any point by pushing your hands and legs against the walls of the well. But you’re just not able to. Mainly because you’ve forgotten about your hands and feet completely.
Similarly, when one falls into this self-denigrating pit of despair, one simply cannot remember to employ the part of the brain that will tell you that you’re overthinking this, and that your past trauma is just not relevant anymore. The world has moved on. How do you deploy this part of your brain?
Write things down. If one were to become slightly technical, there are two types of thinking that the brain employs- Type I and Type II. Type I thinking is the kind of illogical/intuitive/emotional thinking that can lead you into such pits. Type II thinking is the more deliberate, logical form thinking that might save you. When we write things down, or perhaps explain our position to someone else, Type II thinking gets deployed. We may soon realize that the past event just isn’t relevant anymore, or at least not as important as we’re making it out to be.
Another way to think about it is that PTSD is just a failure of computation. Suppose you were bullied as a child. You keep thinking about that, slowly descending further into misery. But what if you deliberately compute the effect of those people in your life? Do these people live near you anymore? No. Do you work with them? No. Have they forgotten about it all? Probably. If you met them again, will they still be horrible to you? Probably not, and definitely not in a few years. When we compute these possibilities, we again deploy Type II thinking, which will lead us out of this spiral.
But why is the brain not always employing Type II thinking anyway? I’m a fairly intelligent person. I should be able to reason myself out of anything. The reason why the brain doesn’t always think in its logical mode is the same reason why the TV doesn’t turn itself on- no one pressed the button. Although the TV is fully capable of showing us our favorite channels, switching it on is still compulsory. Similarly, for the brain to employ Type II thinking, we HAVE to write things down, or perform a computation. This is the only way that the logical part of our brain “switches on”. Without that, the brain will keep chasing us down the same rabbitholes that we’ve been haunted by for years.