The present invention relates to methods for modulating the activity of one or more neurotrophins, such as neural growth factor (NGF), brain derived neurotrophic factor (BDNF), neurotrophin-3, and neurotrophin-4 (NT-4), in an animal and methods for treatment of a disease or disorder in an individual by modulation of neurotrophin activity. The modulation is carried out by interfering with binding between a neurotrophin and a receptor of the Vps10p-domain receptor family or modulating the expression of a receptor of the Vps10p-domain receptor family. Methods for screening for agents capable of modulating neurotrophin activity and agents selected using these screening methods are also disclosed, as are methods for determining the effect of an agent on one or more neurotrophins in cells. The present invention also pertains to methods for modulating the transport of one or more neurotrophins.