The proteins that organize DNA, called histones, can be chemically modified in a variety of ways. The modifications have the effect of turning on/off stretches of the DNA simply by modifying its physical structure (the way the dna is arranged and packed around the histones). There are tons more mods that can happen which have a variety of effects (for example, tune the amount that a gene is expressed). This is called epigenetics if you want to google more.
If you've heard of those studies where if your grandparents experienced a famine it makes some difference in your genetics, one hypothesis is that its caused by this.
(Disclaimer: I've studied pharmacokinetics, though I'm not a pharmacologist)
Vyvanse is a prodrug. That means it metabolizes into the d-enantiomer of amphetamine, whereas Adderall contains a 75-25 mixture of the d- and l-enantiomers. (Enantiomers are like left- and right-handed gloves: they have the same chemical structure, but one is the mirror image of the other. Usually two enantiomers will have similar but slightly different effects; occasionally, they can have incredibly different effects - see thalidomide for an example).
So, without further study, it's hard to know, but it's likely that Vyvanse has a similar long-term profile to Adderall, because the active ingredient (lisdexamfetamine) metabolizes into the active ingredient that makes up about 75% of Adderall.
But, it's possible that the effects described are caused by the l-enantiomer, in which case they won't apply to Vyvanse. It's also possible that lisdexamfetamine itself has its own set of effects which may either cancel out or exacerbate the effects reported by Adderall.
To give you an idea of how prodrugs can have different effects from the drug that they metabolize into: Vyvanse does have a rather nasty feedback loop for some people, because amphetamines suppress the appetite, but lisdexamfetamine is metabolized into the active ingredient using the digestive cycle[0]. For some people, this can cause a really wonky extended release cycle, where they have no appetite mid-day (due to the drug) and can't eat enough to metabolize enough dextroamphetamine to get them through the afternoon, resulting in an afternoon crash. After this wears off and they develop an appetite again (around dinnertime), they'll eat, and then the dosage that was supposed to kick in after lunch finally kicks in after dinner, causing issues sleeping.
[0] This is intentional, and it's why Vyvanse is marketed as an "abuse-resistant" alternative to Adderall, because it's theoretically harder to extract an acute dosage from it.
I think another important consideration might be that peak plasma concentrations on Vyvanse would be lower than on Adderall (because it's more spread out over time). Some effects only happen at certain plasma concentrations.
> I think another important consideration might be that peak plasma concentrations on Vyvanse would be lower than on Adderall (because it's more spread out over time).
Vyvanse is intended to be equivalent to Adderall XR, not IR, so the effects are intended to be spread out in both. If you're comparing to IR, you're no longer really comparing apples to apples anyway.
"There was a catch, though: This symbolic abstraction made the world transparent but the brain opaque. Once everything had been reduced to information governed by logic, the actual mechanics ceased to matter—the tradeoff for universal computation was ontology. ... anything and everything … can be done by an appropriate mechanism, and specifically by a neural mechanism—and that even one, definite mechanism can be ‘universal.’ Inverting the argument: Nothing that we may know or learn about the functioning of the organism can give, without ‘microscopic,’ cytological work any clues regarding the further details of the neural mechanism.”
If something can do anything, than the way in which it can do _any_ thing doesn't much tell you how it does one _particular_ thing. In contrast, a mechanical clock can be inspected, and the way in which it tells time can be understood by its construction.
So, w.r.t to Pitt's research, proving that the brain could compute anything (like a Turing machine) does not help in understanding how it does one particular thing, for e.g. language?
Kind of. It's not the idea that the brain is a Turing machine that's the problem -- I think it's fairly well established that given enough scratch paper, a human _could_ manually execute an algorithm for any computable function. The problem is more specifically that in Pitt's model, all of the behavioral work is offloaded to the abstract logic, leaving none for the physical wetware. Of course, today we know that the brain does have quite a bit of physical structure, and we have learned a lot about how the brain functions by looking at these structures.
