A specific clinical protocol for use toward therapy of defective, diseased and damaged 
cholinergic neurons in the 
mammalian brain, of particular usefulness for treatment of neurodegenerative conditions such as Alzheimer's 
disease. The protocol is practiced by delivering a definite concentration of recombinant 
neurotrophin into, or within close proximity of, identified defective, diseased or damaged brain cells. Using a 
viral vector, the concentration of 
neurotrophin delivered as part of a neurotrophic composition varies from 10<10 >to 10<15 >
neurotrophin encoding viral particles / ml of composition fluid. Each delivery site receives from 2.5 mul to 25 mul of neurotrophic composition, delivered slowly, as in over a period of time 
ranging upwards of 10 minutes / delivery site. Each delivery site is at, or within 500 mum of, a targeted 
cell, and no more than about 10 mm from another delivery site. Stable in situ neurotrophin expression can be achieved for 12 months, or longer.