Amphetamines including Adderall are mildly neurotoxic, but that doesn't seem to bother those that take them.
[1] - https://www.additudemag.com/adhd-life-expectancy-video/#:~:t....
There is a lot of recent research on this and it does not agree with you.
https://www.sciencedirect.com/science/article/abs/pii/S00747...
I believe OP was saying that neurotoxicity has only been definitively shown in higher doses. Granted I highly doubt no studies show neurotoxicity at lower doses, but it doesn't look to be a settled matter.
>Amphetamine Treatment Similar to That Used in the Treatment of Adult Attention-Deficit/Hyperactivity Disorder Damages Dopaminergic Nerve Endings in the Striatum of Adult Nonhuman Primates