We are all getting older. That is one of the main factors influencing the onset of Parkinson’s disease, a common and highly debilitating brain disorder. Yet, how exactly aging affects Parkinson’s disease has long remained unclear. One well-known effect of aging is the gradual accumulation of DNA damage, as cells become less effective at keeping their genetic material intact.
Blood biomarker
In the blood of Parkinson’s patients, researchers from Erasmus MC found a reduction in cellular mechanisms that normally repair DNA. They also identified a marker in the blood that appeared only in patients who later went on to develop more severe Parkinson’s symptoms. Their results were published in Nature Aging.[link]
Lead researcher Pier Mastroberardino explains: ‘Our DNA is constantly being challenged. It can be damaged by external factors such as smoking and UV radiation from sunlight, as well as by normal processes inside the body. Our cells are always busy repairing it. As we age, DNA damage builds up for many complex reasons, impairing normal body functions. This problem seems to be more pronounced in Parkinson’s patients, who show reduced DNA repair mechanisms compared to healthy people of the same age.’
The researchers did not find the same defects in all patients. ‘But the patients who did show defects turned out to experience more severe Parkinson’s symptoms after three years than those who didn’t’, says Mastroberardino.
Database
The researchers reached this conclusion by analyzing a very large database of patients called the Parkinson’s Progression Markers Initiative (PPMI), coordinated by the Michael J. Fox Foundation. They examined blood samples from patients over a three-year period and compared them with data on how the disease progressed.
Currently, predicting the course of Parkinson’s disease is very difficult. ‘If that were possible, it would offer patients and doctors much more certainty,’ says Mastroberardino. ‘And if doctors already know how severe the disease will be in three years, treatment can be planned much more precisely.’
If we could predict the course of Parkinson’s, that would offer patients and doctors much more certainty.
Golden standard
The gold standard in Parkinson’s treatment is replacing dopamine, Mastroberardino says. In Parkinson’s patients the loss of nerve cells causes a shortage of dopamine, which leads to tremors and other symptoms. ‘Dopamine acts like a brake on your movements,’ he explains. ‘When that brake fails, you start to tremble. But giving extra dopamine can also have severe side effects, such as dyskinesia, uncontrolled, erratic movements. So ideally, you only want to use that medication when you’re sure it will really be needed.’
In theory, the team’s discovery means that during a patient’s first visit for Parkinson’s disease, a simple blood test could help predicting how the disease will progress. Obviously, more work is required to reliably move these findings from the lab bench to the doctor’s office.
