Levodopa "Wears Off" Faster for Women

A large Italian study followed people with Parkinson’s disease who were starting levodopa for the first time and found clear differences between men and women in how the medicine worked over the next two years. Levodopa remains the gold-standard treatment for Parkinson’s symptoms, but its benefits can fade between doses (often called “wearing-off”), and some people develop involuntary movements known as dyskinesia. This research suggests those complications show up more often—and earlier—in women. Researchers tracked 216 participants who completed the study: 139 men and 77 women. Everyone began levodopa after the initial clinic visit and was reassessed over two years using standard Parkinson’s rating tools. By the end, almost two thirds of the women had experienced wearing-off compared with just over half of the men. Dyskinesia told an even starker story: about one in seven women developed it, versus one in twenty men. When the team ran more advanced analyses that took age, symptom severity, other Parkinson’s medicines, and body weight into account, being female remained the strongest predictor for both wearing-off and dyskinesia. Younger age also mattered: older participants were less likely to have wearing-off. Higher baseline motor symptom scores nudged dyskinesia risk upward as well. Why might women be more affected? The study didn’t pin down a single cause, but it points away from obvious suspects. Average levodopa doses were similar between men and women during most of the follow-up, and body weight did not explain the differences. A separate line of research has shown that women can reach higher blood levels of levodopa than men from the same dose, possibly due to differences in drug metabolism and gut transit time. Hormones, sex-chromosome effects, and subtle differences in brain circuitry may also play roles. A genetics substudy looking across dozens of Parkinson’s and dyskinesia-related genes did not find a clear genetic explanation for the sex gap. What does this mean in everyday care? First, it reinforces that Parkinson’s is not one-size-fits-all. Women starting levodopa may need closer early follow-up to spot wearing-off and dyskinesia, and care teams might consider dose timing, smaller but more frequent doses, adjunct medications, or extended-release options sooner if fluctuations appear. Second, it strengthens the case for “sex-informed” Parkinson’s care and research, from how trials are designed to how clinicians counsel patients about benefits and risks. Finally, it’s a reminder for everyone—men and women—that changes in symptom control over time are common on levodopa and not a personal failure. If movement feels less predictable, or new fidgety or writhing movements emerge, that is useful information your clinician can act on. Like any study, there are limits. Participants were all treated at centers in Italy, and the COVID-19 pandemic led to drop-outs that could introduce bias. Even so, the design—starting at the moment levodopa began and following people prospectively—adds weight to the findings. The practical takeaway is simple. If you’re beginning levodopa, especially if you’re a woman or on the younger side, plan for regular check-ins, keep a brief symptom diary to capture times of day when control fades or movements appear, and bring that record to your appointments. The goal isn’t to use less medicine; it’s to use it more intelligently for your biology.