Just for a little background info...I am female, 27 years old. Growing up, I was always bright and creative. During my late teens and early adulthood I have used marijuana, alcohol, meth, acid, shrooms, coke, E, nitrous, and ephedrine (pill form). I can honestly say that I have experienced some long term and short term effects from all of these.
Marijuana - I have smoked for 11 years either everyday or several times per week. I do not use at work or school. Positive permanent effects include increased creativty, ability to relax and sleep soundly, alleviated depression, BIG laughs! Negative effects include short term memory loss, the feeling of being "stoned over" the next day (clouded thoughts, minor fatigue), minor, occasional paranoia while high, loss of sex drive. In reading up on this drug, I feel the only permanent effects it may have are lung damage and moderate STML.
Alcohol - This drug effects my body in a negative way and so I limit my consumption to about once or twice a month. Positive effects include lowered social inhibitions. Negative effects include the desire to smoke cigarettes, headache, loss of concentration, nausea, brain dead feeling the next day.
Meth - I once had a serious problem with this drug. It is toxic. I went from being 5'2", 115 lbs. to 85 lbs.!! Positive effects (short term) euphoria, chattiness, increased energy. Negative effects (short term) weight loss, paranoia, loss of motivation, depression, (long term) degeneration of bone mass including teeth, anxiety, fidgityness.
Acid - I did this drug between 5 and 10 times (mild doses). I can say that I have experienced no negative long term effects. Positive effects include the retention of all of the valuable insights that LSD offers.
Shrooms - See Acid.
Coke - I only tried this drug once and didn't like the way I craved it intensely after the comedown. Lack of use = no permanent effects.
E - I have done this drug about 10 times. It has been about 5 years since I have done it and I feel I have no permanent negative effects. I never took more than 2 pills a night and have given my body time to heal. I have retained the ability to empathize and my love of dancing and music has continued to grow. When I was doing it, I was also using meth and became extremely paranoid. The paranoia has gone away.
Nitrous, ephedrine - haven't done these enough to have long term effects set in.
The only drugs I currently use are alcohol and marijuana and I like it that way.
In summary, I feel I have experienced mild permanent effects of drug use (mostly related to meth). My intelligence has not dwindled, I still have creative juices flowing, have a passion for life and high expectations for myself. Moderation is helpful.