How will herion affect the brain in the long term?

Varies: Im not a neuroscientist but the effects of drugs on the brain would depend on many variables, including baseline function, length of time and extent of exposure and other exposures.

It destroys lives: Heroin use/addiction destroys many lives, the users and their family and friends, and negatively affect society in general (huge healthcare recourse/cost burden). Some of the effects on the brain itself is pictured here. It also affect your circulatory/respiratory system. Stop it now and seek help--only u can turn your life around. Life is precious. Be good. Be alive! good luck.