Right and Left Brain
Why Parkinson’s disease and other neurological disorders impact one side of the body before the other is explained in recent findings.

The most puzzling and persistent mysteries in neuroscience may have been solved by scientists: the reason why some people are “right-brained” and others are “left-brained.”

How certain genes on each side of the brain are switched “on” and “off” through a process called epigenetic regulation is where the answer lies in. The findings may explain why Parkinson’s disease and other neurological disorders frequently affect one side of the body first, a revelation that has far-reaching implications for development of potential future treatments.

Published in the journal Genome Biology, this study was led by Van Andel Institute’s Viviane Labrie, Ph.D

Labrie said “The mechanisms underlying brain asymmetry have been an elephant in the room for decades.” “It’s thrilling to finally uncover its cause, particularly given its potential for helping us better understand and, hopefully one day, better treat diseases like Parkinson’s” she said further.

Though its epigenetics that dictate whether those genes are switched “on” or “off” each cell in the brain has the same genes. Numerous epigenetic differences between the hemispheres of healthy brains that are linked to variations in gene activity were discovered by Labrie and her collaborators. These differences, or asymmetry, could notably make one side of the brain more vulnerable to neurological diseases.

For instance, epigenetic anomalies on one side of the brain could turn that hemisphere more vulnerable to the processes that cause the death of brain cells in Parkinson’s. The appearance of the disease’s hallmark symptoms, such as tremor, on one side of the body before the other, is led by the differences in cell death across hemispheres. Symptoms on the side that’s first affected often are more severe as the disease progresses compared to symptoms on the other side of the body.

A vital window into the various biological pathways that contribute to symptom asymmetry in Parkinson’s, including brain cell development, immune function and cellular communication are the findings acquired by the scientists.

Labrie said “We all start out with noticeable differences between the left and right sides of our brains. As we grow older, however, our hemispheres become more epigenetically similar. For Parkinson’s, this is important: people whose hemispheres are more alike early in life experienced more rapid disease progression, while people whose hemispheres were more asymmetric had delayed disease progression.” “Many of these changes are combined around genes known to impact Parkinson’s risk. There is big potential to translate these discoveries into new therapeutic methods.”

Other neurological diseases like Alzheimer’s is where Labrie has begun to look for this phenomenon.

Among the first studies to parse the molecular causes of brain asymmetry is where this research is included. During mid-20th century, Roger Sperry, whose groundbreaking work with split-brain patients earned him a Nobel Prize, conducted research on the left versus right brain.

Source: Van Andel Institute