The cause of Parkinson's disease (PD) is a dopamine deficiency in the brain. Dopamine is a neurotransmitter, a chemical messenger in the nervous system. In PD the neural cells that produce dopamine deteriorate, and the normal rate of dopamine production decreases.
In this study, researchers examined the brain's ability to increase dopamine production by infusing human brain derived molecules called glial cell line-derived neurotrophic factor (GDNF). Five patients with advanced PD underwent insertion of a small tube into their brains, through which the GDNF was infused over the course of two years.
Using the Unified Parkinson's Disease Rating Scale (UPDRS), which measures many facets of PD progression, study participants were tested pre- and post-operatively at six-month intervals for two years. They were also examined using PET imaging to determine the uptake (level) of 18F-dopa, a dopamine generator.
"We were very encouraged by our results," notes study author Gary Hotton, BSc, MBBS, from Professor D. Brooks' research group at Imperial College and Hammersmith Hospital, London. "The patients experienced a 41 percent improvement in total UPDRS and a 44 percent improvement in the UPDRS motor function section."
This study shows that chronic infusion of GDNF results in a clinical improvement in PD, sustained for at least two years. It also showed a significant increase in 18F-dopa uptake localized to the tip of the infusion tube. Further study may be warranted to determine continued effects.