INS and neurodegenerative disease: These technologies will help broaden and exploit the therapeutic potentialof this pathway and may shift the current paradigm of neurodegenerative diseases.Insulin is the most widely studied drug for nose-to-brain delivery and, there issignificant level 2 and level 3 evidence suggesting insulin and other substances canbe delivered directly into the brain through the aforementioned pathways.Limitations of studies evaluating other substances are mainly due to lack ofrandomization, blinding, or case studies.