Parkinson’s disease has long been recognized by tremors and a characteristic stiffness and sluggish gait. It has been thought that the cause of the disease was the death of neurons in the mid-brain that produces the neurotransmitter dopamine. The belief was supported by the fact that dopamine is known to help maintain motion control.

Emory University researchers speculated that another area of the brain may play a significant role in Parkinson’s disease. For some time, scientists have known that deceased Parkinson’s patients have a loss of norepinephrine-producing cells. The role of the norepinephrine neurons is to regulate the release of dopamine. Without the norepinephrine cells, dopamine can be produced, but not released as needed. The lack of dopamine is what creates the characteristic Parkinson’s stiffness and sluggish gait.

Researchers suggest that Parkinson’s patients be given a tricyclic antidepressant in addition to the drug L-dopa.