Mental Focus supplements??

I have a question that's probably been discussed before, but I did a search and could not come up with the answer I was looking for. I know everybody has their poisons, but I fear I have done permanent, or long-lasting damage to myself from rec. drugs. First off, I know I brought it upon myself, so I'll understand the flames, but it was pretty much self medicating severe depression caused by many things. To keep it short, over almost the last 2 years, I have done QUITE a bit of E not to mention an ample amount of blow. I vowed never to touch anything besides alcohol from now on over a month ago. However, like a stupid kid I never thought about the future, and as of now I still have a slightly "fuzzy" feeling.(not to mention I believe worse depression) By that I mean, extremely hard to remember things someone just told me; pretty much just out of mental focus. I have been taking 5HTP, as I know it helps to replenish serotonin in the brain, but I was wondering if anyone could suggest the best supplement/vitamin to help with memory, mental agility, ect. Thanks for any advice, it means a lot.

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