NSAIDs are drugs with analgesic, antipyretic and anti-inflammatory effects - they reduce pain, fever and inflammation.
Certain NSAIDs, including ibuprofen and aspirin, have become accepted as relatively safe and are available over-the-counter without prescription.
The study, conducted by Beate Ritz, MD, PhD, with University of California (UCLA) School of Public Health, Angelika D. Wahner, PhD, with the UCLA School of Public Health in Los Angeles and team, analysed 579 men and women, half of whom had Parkinson's disease.
The participants were questioned if they had taken aspirin and if they had taken non-aspirin NSAIDs, such as ibuprofen, once a week or more at any point in their life for at least a month.
Patients were considered regular users of aspirin or non-aspirin NSAIDs if they took two or more pills a week for at least one month. Non-regular users were those who took fewer pills.
The analysis found that regular users of non-aspirin NSAIDs reduced their risk of Parkinson's disease by as much as 60 percent compared to non-regular users and non-users.
Women who were regular users of aspirin reduced their risk of Parkinson's disease by 40 percent, especially among those who regularly used aspirin for more than two years.
"Given our results and the growing burden of Parkinson's disease as people age, there's a pressing need for further studies explaining why these drugs may play a protective role," Wahner said.
Wahner said that the findings suggested that NSAIDs were protective against Parkinson's disease, with a particularly strong protective effect among regular users of non-aspirin NSAIDs, especially those who reported two or more years of use.
"Our findings suggest NSAIDs are protective against Parkinson's disease, with a particularly strong protective effect among regular users of non-aspirin NSAIDs, especially those who reported two or more years of use," Wahner said.
"Interestingly, aspirin only benefited women. It may be that men are taking lower doses of aspirin for heart problems, while women may be using higher doses for arthritis or headaches," she said.
Co-researcher Ritz said that it is the anti-inflammatory agent in NSAIDs that might contribute to the observed protective effect of the drugs.
"It's possible the anti-inflammatory agent in NSAIDs may contribute to the observed protective effect of the drugs, but the exact mechanism isn't clear and further research is needed," Ritz said.
The study is published in Neurology.