Hi, I have severe treatment resistant depression for years. I have sever refractory anhedonia that comes with it. I’ve tried tons meds and combos. From research and my own experiment I found out that lithium with doses of 600 mg or more have an impact on the medications that I’m taking and without it I barely get a response. I am augmenting with phenelzine (Nardil) 90mg but I want to go up on the lithium to make it work even better. In the past I’ve taken lithium up to 450mg alone and it hasn’t done much but I read that with augments with TCA and MAOI it can be useful to treat severe endogenous/melancholic/biological/treatment resistant depression. I highly suspect that I am leaning toward bipolar 2 as I fit almost all symptoms. 
I am 4 weeks on Nardil with almost 2 weeks being on 90mg, not sure if it’s kicked in yet, can’t tell but I hear it takes a while to kick in. 
I started lithium almost 2 weeks ago and went up to 600mg in a few days. I take all night just before bed. I’ve tried 900mg for 2 days but it was too much. My main side effects which I’m concerned are cognitive. I feel kind of dumber, very hard to focus, can’t critically think, easily distracted, poor short term memory, not meaningful and isolated from everyone yet somehow I feel more at ease (hard to explain but i feel it’s cleared up my mind). I have physical symptoms too like shaking hands, sensitivity i to cold (probably thyroid getting hit), blurred vision, feeling weak, but I learned to deal with them and wait it out/toughen them. I also drink lots of water and take modafinil during the day. But the cognitive side effects are just omg. My question is, do they go away, how do you deal with them? I want to go up but I’m concerned with side effects...
Otherwise I’m pretty health for 26 year old male. I really want to stay on it, feels like a very good drug in fact it’s the only drug that’s done anything for depression but want to know how to tolerate the mental side effects.