Can the brain recover from drug abuse over time?

yes the brain can recover but it takes time. We only use a small portion of the brain and when one part is damaged like from killing brain cells esp from LSD or huffing, then other parts can compensate. If you keep using though you do run the risk esp with huffing or hallucinogens of frying your brain completely like some people you may have seen that can no longer form a sentence. As far as the chemicals in the brain things like anti depressants can make you feel better in the mean time but they arent forever so that your brain can start making it's own chemicals again. Basically drugs take the chemicals in your brain and make you use them a lot at once hence the "high" then then stop making them for awhile to build them back up. After 6 years of using give yourself at least a year and do things to help like excercise and hobbies that make you feel good - this will help push the body to make the chemicals to make you feel good again and talk to talk to a doc about very mild antidepressants like wellbutrin that may help with sleeping better etc. Don't drink and don't do drugs and you should start feeling better soon :-)