A new study has found that small strokes, also known as "silent" strokes, can lead to Parkinson's disease. While the symptoms of a severe stroke are immediate and apparent, a silent stroke can often show no outward symptoms. The link to Parkinson's could help explain why Parkinson's disease symptoms often appear to pop up out of nowhere.
A silent stroke occurs when a blood vessel in the brain is blocked for a very short time. The study, published this month in the journal Brain Behavior and Immunity, demonstrated that a silent stroke can lead to the death of dopaminergic neurons in the substantia nigra, a brain region responsible for movement and coordination.
"At the moment we don't know why dopaminergic neurons start to die in the brain and therefore why people get Parkinson's disease," said Dr. Emmanuel Pinteaux, who led the research at the University of Manchester. "There have been suggestions that oxidative stress and aging are responsible. What we wanted to do in our study was to look at what happens in the brain away from the immediate area where a silent stroke has occurred and whether that could lead to damage that might result in Parkinson's disease."
The finding was surprising to researchers, who induced mild strokes in mice to simulate silent strokes. Six days after the strokes, Pinteaux and his team found neurodegeneration in the substantia nigra of the mice.
"It is well known that inflammation following a stroke can be very damaging to the brain," said Pinteaux. "But what we didn't fully appreciate was the impact on areas of the brain away from the location of the stroke. Our work identifying that a silent stroke can lead to Parkinson's disease shows it is more important than ever to ensure stroke patients have swift access to anti-inflammatory medication. These drugs could potentially either delay or stop the on-set of Parkinson's disease."