That is not true. All studies have shown they are only neurotoxic if abused and by abused I mean taking nearly 10x of a normal dose. At that level
Of abuse anything is neurotoxic.
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