I would be curious if other knowledgeable folks agree that pure meth isn’t that much different from Adderall on dimensions that are likely to be relevant.
Adderall is regular (non-methylated) amphetamine, specifically a mixture of levo-amphetamine and dextro-amphetamine. There are minor differences in effect profile between methamphetamine and amphetamine, the biggest of these minor differences being in neuroprotectivity (it’s been a while since I’ve done the research but iirc amphetamine is mildly neuroprotective while meth is neutral or mildly negative, due to meth interrupting some metabolizing process). The major difference is that milligram-for-milligram, meth is 2-5x more potent than regular amphetamine.
The perception that they are very different is valid, though, because amphetamine is usually consumed therapeutically (lower doses, guaranteed purity, controlled dosing schedule, safer administration route) while meth is usually consumed recreationally (higher doses, unknown and often dubious purity, erratic dosing schedule, riskier administration routes). Injecting a quarter of a gram of street meth over a three day binge is much more harmful than taking 40mg Adderall extended release formulation by mouth every morning.
On some level, it is similar as they are both stimulants and nearly the same chemical. But my own research suggests the methyl group has a significant effect on how the body metabolizes the drug.
The methyl group makes it fat-soluble which allows it to cross the blood brain barrier. Apparently this causes it to have an effect on dopamine and serotonin receptors which it would otherwise not - hence the euphoric effect. It also cleaves into amphetamine in the blood stream which gives it a significantly higher half-life.
How you administer a drug is important, which is self explanatory. Most newer ADHD stimulants are made in such that they must be metabolized through the stomach.
Additionally, the dosage is important. Meth is not only more potent, but when abused is likely to be taken in 10x (or more) amount than a therapeutic dose.
So.. safe to say they are chemically similar but different in practice. This info is from my quick googling. I’m on a therapeutic dose of Adderall, and given its effect on my blood pressure I would be concerned taking meth due to all of the above. And this is why I have a doctor to help me with all of this.