How can experimental drugs affect the brain?

I just recently learned from my "friend" that this particular experimental drug we did about a year ago is on the level of cocaine. I had suspicions the day after because I really wanted more, I was grinding my teeth still, and I wasn't myself. I got better though a few days after. But even today I feel like a different person. I forget things alot more, I feel like my creativity decreased, and I lost interest in things i'm normally into. It could be because of other things, but I was wondering if those drugs I did effected my brain. I snorted alot of lines in one night because I paid for most of it. I lost track of how much I did. I just feel... stupid now. The drug was called mkat.