I've just been wondering about this myself. I'm now medicated and can not seem to find the links to support my viewpoints. It's like there's a big white nothingness where the info used to be.
On the other hand my head is now quite and I'm sleeping better
But too when I'm in the depressive state my mind just goes blank, trying to form the basic thoughts are out of my reach

There has to be a place between the two extremes a place where I'm the intelligent person people used to say I was, currently I feel like an empty shell.