Bumping an old thread posted by a faggot, but as another swiss-cheese brained, neuroatypical spaz, I do have a bit of insight on how you can go about this, for anyone that may still be interested.
If you're actually diagnosed with ADHD you probably get medication for it, usually our good ol' buddy amphetamine sulfate or adderall. Even if you're not getting a script it's ridiculously easy to walk into a doctor's, tell them you can't concentrate, and get one. And if you're such a screw up you can't even manage that, it ridiculously easy to buy the stuff off literally any college student. Check your local library kids, someone is dealing it near you.
Now, again, we're assuming you're not the homeless scum of the earth and you've got access to some kind of medical care. Tell your doctor you're depressed and get some anti-depressants. What you are looking for are SSRIs (Selective serotonin reuptake inhibitor). That's your Prozac, your Zoloft, your Celexa. That shit.
It's better if you get the scripts from two different doctors, assuming they're busy and/or negligent they won't bother to look up your amphetamine prescription or they'll just give you a warning not to take them together before shoo'ing you out of their office so they can service the next snot-nosed crybaby.
Now what you do it you take them together. Not just a standard dose, you wanna take A LOT of both of them. And if you hit the jackpot, you'll die a drawn out, miserable, suffering death that might pass for an accident if the coroner's been drinking.
When you combine amphetamines with SSRIs you get this neat side effect called Serotonin Storm (or Syndrome, or Toxicity, or Toxidrome, whatever). It can be deadly, but it can also not kill you too, so watch out for that. You get a lot of the same side effects of overdosing on adderall, the twitching, tachycardia, hallucinations. But you also get additional benefits like seizure, coma, and death!
You can read more about it if you like:
https://en.wikipedia.org/wiki/Serotonin_syndrome
I found out about it first hand awhile back, taking my pills by the fist full because I frankly stopped caring about life. My roommate got home and found me twitching and foaming on the floor. Got me medical attention and lo and behold I stand before you today, a bit shakier but altogether very much alive.
Would I recommend it? No, not really. It was terrifying and awful, and seeing as how I survived it, I couldn't guarantee it's effectiveness. But if you're too huge of a pussy to do something 100% certain like a shot gun shell to the brain, these are medications that any 18 year old with access to a doctor can get a hold of easily and CAN produce fatal results. And takes only a minute of your time, so even the most scatter brained of the attention deficit can be settled the fuck down for good!