Brains cells affected by Parkinson's disease die prematurely because they are prone to burning out "like an overheating motor", according to new research.
Scientists writing in the journal Current Biology, said they found the cells targeted by the disease require unusually high levels of energy to carry out their job of controlling movement.
Parkinson's is a degenerative disease for which there is currently no cure.
The Canadian researchers studied the disease in mice and focused on the role of mitochondria, which enable cells to grow and release chemicals such as dopamine - a compound Parkinson's sufferers are deficient in.
They found the complex structure of neurons in the substantia nigra region meant mitochondria were constantly working at "burnout rates" and so were more likely to degenerate and die with age.
Lead researcher Louis-Eric Trudeau, a professor at the University of Montreal, said: "Like a motor constantly running at high speed, these neurons need to produce an incredible amount of energy to function. They appear to exhaust themselves and die prematurely.
"To use the analogy of a motor, a car that overheats will burn significantly more fuel, and, not surprisingly, end up at the garage more often.
"It's possible that new medications could be developed to help the neurons in question reduce their energy consumption or produce energy more efficiently, which would reduce accumulated damage over the years."
Unlike Alzheimer's, which targets billions of brain cells, Parkinson's affects tens or hundreds of thousands of neurons in a few specific regions of the brain.
Parkinson's UK director of research Dr Arthur Roach said he hoped the study would spark innovation in treating the condition.
"Out of the billions of cells in the brain, it is always the same small group that degenerate and die in Parkinson's. We don't know why only these cells are affected," he said.
"This study provides strong support to the idea that it is the unique structure and function of these cells that makes them especially susceptible to a damaging process called oxidative stress.
"We hope that this study will ... lead to new treatments based on the most up-to-date ideas about oxidative stress."