NGF and Parkinson disease: The above studies indicate that acetylcholinesterase inhibitors alone are insufficient to achieve clinical expectations in the treatment of PDD.21,22 Studies have demonstrated the effectiveness of NGF in promoting the development of peripheral and central neurons, and inhibiting sustained neuronal damage in patients with PD.13,14 Liu Y et al.14 found that NGF in combination with the conventional pharmaceutical treatment regimen was able to increase the total efficacy of PD treatment to 88.46%, significantly improving neurological function of the patients.