The anti-inflammatory drug ibuprofen may act as a neuroprotective agent against the risk of Parkinson’s disease, according to researchers at the Harvard School of Public Health.

In the observational study, participants who regularly used ibuprofen were 40 percent less likely to develop Parkinson’s disease over a six-year period, according to lead researcher Xiang Gao, an instructor in medicine at HSPH.

These findings confirmed the results of a 2005 study that found that users of non-steroidal, anti-inflammatory drugs—including ibuprofen—displayed a lower risk of developing Parkinson’s disease.

The current study focused on ibuprofen, which can be purchased over the counter in the form of popular brands such as Advil.

Over six years, 130,000 subjects self-reported their health statuses and specifically noted their use of ibuprofen and whether they had been diagnosed with Parkinson’s disease.

The study found that 15 to 20 percent of participants regularly used ibuprofen, and 291 individuals were diagnosed with the disease within the six-year timeframe.

Despite the suggestions of a correlation between ibuprofen use and risk of Parkinson’s disease, the Harvard researchers said that the study’s findings cannot be used to reach any conclusions because the research was purely observational and did not examine causality.

The next step is to “take advantage” of the study’s findings by further exploring the relationship between ibuprofen use and risk of Parkinson’s disease, said Michael A. Schwarzschild, an associate professor of neurology at Harvard Medical School and one of the study’s authors.

Schwarzschild said that it is not surprising that anti-inflammatory medication like ibuprofen may help reduce the risk of the disease, which involves inflammation of the brain. But scientists have yet to determine exactly why ibuprofen may be more effective as a neuroprotective agent than other anti-inflammatory drugs, Schwarzschild explained.

Parkinson’s disease is a chronic neurological disorder that progressively slows down movement. Dubbed “the shaking palsy” by its discoverer James Parkinson, the disease is characterized by a “rest tremor,” a steady shaking that typically begins in one hand while a patient is at rest, according to Schwarzschild.

The disease is also associated with dementia, depression, and other disorders. According to the National Parkinson Foundation, 60,000 new cases of Parkinson’s disease are diagnosed each year.

The study—which will be presented in April at the American Academy of Neurology meeting in Toronto—also involved researchers Honglei Chen and Alberto Ascherio, a professor of epidemiology and nutrition at HMS.