Uric Acid Blood Levels Linked to Dyskinesia Risk in Men with Parkinson’s

High blood levels of uric acid, a powerful antioxidant, are linked to an increased risk of levodopa-induced dyskinesia in men with Parkinson’s disease, study finds.

The study, “Sex-specific association of urate and levodopa-induced dyskinesia in Parkinson’s disease,” was published in the European Journal of Neurology.

Dyskinesia, or involuntary muscle movements, is one of the most common complications associated with long-term treatment with levodopa, a dopamine replacement therapy that is a mainstay treatment of Parkinson’s symptoms.

A patient’s risk of developing levodopa-induced dyskinesia (LID) is not only tied to levodopa exposure and dosage. Previous studies have found that women — female sex itself — and individuals who develop Parkinson’s early in life also are at a higher risk of LID.

Uric acid is a major antioxidant molecule, and associated with a lower risk of developing Parkinson’s and slower disease progression. However, evidence reported by some studies suggests its effects may be sex-dependent, as only men, but not women, with higher levels of uric acid are at a lower risk of developing this disease.

Until now, the possible “association between LID and baseline UA [uric acid] levels in patients with PD [Parkinson’s disease] has not been studied,” researchers wrote.

To understand if uric acid can influence LID risk in a sex-dependent manner, researchers in South Korea reviewed the medical records of 152 Parkinson’s patients — 78 men and 74 women, with a mean age at disease onset of 63.97 — treated at a specialized outpatient clinic from March 2009 to June 2013. All were monitored for more than two years.

Statistical analyses were used to evaluate the possible effects of uric acid levels on LID risk in men and women separately.

During follow-up, a total of 23 men (29.5%) and 30 women (40.5%) developed levodopa-induced dyskinesia.

Blood levels of uric acid were found to be influenced by patients’ sex. However, contrary to researchers’ expectations, higher levels of uric acid were associated with a greater risk of LID in men, but not in women.

Men with Parkinson’s whose blood levels higher than 7.2 mg/dl of uric acid had a 5.7 times increased risk of developing LID, compared with those whose levels were lower than 7.2 mg/dl.

“Our study unexpectedly demonstrated that high UA level was an independent predictor of future development of LID in male PD patients,” the researchers wrote.

“A further replicative study with a larger sample size is needed to draw a firmer conclusion,” they wrote.