Searching for the First Sign

The Role and Reputation of Dopamine

Dopamine has been implicated in causing everything from love to lust to drug addiction. Love, motivation and movement all begin in the brain as dopamine—hopping from one neuron to another.

Dopamine leaves one neuron and slips through the space between the nerve cells (synapse). Then it collides with a receptor on the neighboring neuron, sending a signal down to the cell and igniting a chain of events that results in a movement, feeling or action.

Because dopamine plays an important role in kicking off movement in the body, it has been considered the major culprit in causing Parkinson's disease, a degenerative disease that may begin as a barely noticeable tremor in one hand, then over time interferes with movement, muscle control and balance. Symptoms of the disease appear when dopamine-producing nerve cells become damaged or die.

But scientists are still charting the brain’s complex system of neurons and the chemicals that navigate them.

Where Does Parkinson's Disease Really Start?

Echo Tan, MD, a neurologist in the Cedars-Sinai Movement Disorders Program, and her colleagues believe that the earliest signs of Parkinson’s may emerge before the dopamine-making cells begin to be destroyed.

"The longtime notion is that it’s dopamine—but it's a lot more complicated than that," Tan said. "Without finding the real reason behind Parkinson's, we can't find a cure. We're looking for where Parkinson's really starts. What's the true reason? What is altered in the brain and the body to cause Parkinson's?"

The Search for Answers

Hoping to find the earliest detectable changes, Tan and her colleagues are scouring brain scans from patients in early stages of Parkinson's disease, looking for clues to what parts of the brain may have been first affected and what other brain chemicals may play a role in the disease. "We want to find the first changes, because that’s probably where the start of the disease is," Tan said.

The patients Tan treats for Parkinson's drive her desire to better understand the origins of the disease. She hopes a better understanding of what's happening in the brain will lead to better treatments—and perhaps even a cure.