When I heard the news I thought of maybe going through their catalogue again in tribute but that would take a few weeks listening to that and nothing else (depending on how many of the non-studio stuff I would put back on).
Of course it's unsurprising. His drugs of choice, which he used heavily since he was a teenager, were alcohol and methamphetamine, both of which are neurotoxic -- and it definitely showed the last decade. I've done my share of dextroamphetamine but that doesn't kill brain cells, thank God.
Seriously, never get addicted to amphetamines. They're one of the hardest things to quit psychologically since they make everything better and they make you effortlessly better at everything.