Probably the biggest one is levetiracetam (also known as Keppra). If you read the warning label, it says it can induce "mood changes", which is a euphemistic way of saying "it can turn you into an uncontrollable rage monster".
I've been there. Whatever you think you know about getting ticked off, you haven't felt angry until you've felt it on Keppra. There is no gradation of anger-- no "subtly annoyed", no "getting ticked off", no "this is really getting me angry". Just "zero" and "Incredible Hulk on a bad day". The stuff that annoys you may not be anything that annoyed you in the past, but now it's something that makes you want to bash somebody's skull against the pavement until it goes soft. And there is no warning, no ramp-up-- you just suddenly find yourself enraged beyond all human comprehension, and you're doing everything you can just to restrict yourself to yelling incoherently instead of resorting to physical violence.
There's even a cute nickname for this whole horror show: "Kepprage".
I'm off levetiracetam now (onto lamotrigine, which is also prescribed as an antidepressant). But it scared me pretty badly. I genuinely fear getting angry now-- because I worry that I'm going to wind up back where I was. I was single when I was on Keppra, but I'm in a relationship now-- it scares me to think what I might do if I ever get back to Kepprage levels of anger, because it could easily cost me my partner.
So, to your question: was I a different person on Keppra? I mean, I still responded to my name and worked the same job and had the same favorite foods and such. But I was a lot angrier, I was getting angry all the time, and there was no off switch. It's a valid philosophical question as to whether that makes me a "a different person". Looking to your example, consider that feeling that you have on alcohol, and its assorted side effects and behavioral changes. Now imagine that you were stuck in that mode, 24/7. Would you be "a different person"?
L-DOPA's significant side effects and risks are very well known to doctors. No one should be prescribed L-DOPA unless they have severe Parkinson's disease, and even then the L-DOPA dose should be actively minimized.
The impulsive behavior side effect of L-DOPA is so well known that it has its own Wikipedia page: https://en.wikipedia.org/wiki/Dopamine_dysregulation_syndrom...
We should all be aware of potential side effects, but it's also important avoid the false dilemma fallacy. These patients aren't choosing between being healthy or taking L-DOPA. They're forced to choose between suffering from severe Parkinson's disease symptoms or risking the side effects of the medication. When the side effects outweigh the benefits, the medication should be discontinued. When the side effects are less than the underlying disease, the medication should be continued.
It did nothing noticeable. At higher dosages for 1 day I felt somewhat dizzy/nauseous, so I never tried that again (there is some research mentioning it can damage receptors irreparably). At the prescribed dosage, after a month I dropped it, as there was no improvement, no change.
Really, the only things I tried that had an actual effect were alcohol, cannabis, phenylethylamine (with nicotine! Does not work without it. And can probably kill you with alcohol, beware!), cocaine, aniracetam and sulbutiamine.
No wonder they're mostly banned, because they exhibit actual effects, but are not for any specific sickness. Sad, I'd say lack of alertness and a bad mood should be treated as sickness.
I doubt that it changed who I am, but it changed on how I act. Well, of course it depends on definition of who we are to start with. They certainly affect on how do you feel and how do you think, but when effects wear off, you typically return to your former ways. Maybe with new thoughts or new look at your life. But that's it.
I continue to see those kind of meds as a mere tools, which you can use to alter your thinking for a period of time to get yourself a fresh look at ordinary things. I think that therapeutic effect exists here only if you get some realization about your former ways.
Some meds made me worry less about my life when I've realized that worrying doesn't actual solve anything, it just makes you feel worse.
Some made me more emphatic towards people when I've realized that everyone is exactly as same as me, just with different life story.
an extreme example for environmental factors radically changing people’s behavior is lead poisoning.
My brother went from being pretty wealthy to homeless in 7 years.
His personality was greatly changed by the meds or PD. It's not clear, but the side effects of Mirapex are very clear. It is criminal that that drug is handed out like candy, without any discussion of the potential problems it creates.
Anyways, circa 1998, battling a serious fungal infection, an alternative treatments doctor (not homeopathy or something, this was in Seattle) put me on some kind of medication. I realized on my 3rd or 4th rage incident that the medicine triggered something which put me on the edge that even a small discomfort would trigger me. It was not the skin issues, it was just my mind on high. I have never been on (recreational) drugs before or after and barely drink alcohol, so not sure if any drugs cause similar behavior. I did not stop the medication once I realized it but I did try to be conscious of the effect and was able to control the rage better (but still not 100%).
[ Add: As I think more, the doctor was in sports medicine, so maybe he used somethings that he usually tried on athletes. ]