>While Hadland says it would take a lot of repeated heavy use of nitrous oxide to see these effects, over time such use could also cause permanent neurological issues.
This is not a could. Repeated abuse of nitrous, perhaps as little as daily use over 2 months, does cause neurological issues, including spinal cord damage and paralysis [1].
[1] https://sci-hub.ru/https://pubmed.ncbi.nlm.nih.gov/31625167/