> is worse than alcohol for your brain

It depends on the definition of "worse". If cell death over time, then maybe alcohol is worse. If it's how much a recreational/entertaining dose disturbs the workings of the mind, the operation/rational/ability to live a normal life, which is the purpose of the mind, then I would say heroin is worse.

I would assume the amount of dopamine a drug releases is directly related to its ability to disrupt someones life.