Ambroxol fails to slow cognitive decline in Italian Parkinson's trial, but larger UK movement study is still on

The search for a way to slow down Parkinson’s has taken an important turn with the publication of results from a clinical trial in Italy called AMBITIOUS. This study looked at whether a common, inexpensive cough medicine called ambroxol could help. While the results are a bit of a mixed bag, they offer some incredibly important clues. Here is what happened in the Italian trial, how it compares to the British study: The Italian AMBITIOUS trial Italian researchers report that the common cough medicine ambroxol did not slow down cognitive decline in a clinical trial for people with a genetic form of Parkinson's. A year-long trial testing a common cough medicine called ambroxol as a potential treatment for people with a genetic form of Parkinson's has finished, and the results are mixed. While the medicine proved safe and well tolerated, it did not achieve its main goal of slowing down memory and thinking changes. In fact, some of the results suggested a slight decline in certain cognitive tests. The study focused on sixty-five people with Parkinson's who carry a specific variant in a gene known as GBA1. This genetic variant is a common risk factor for the condition, and it often leads to a higher risk of developing cognitive difficulties. Because ambroxol is known to help clear cellular waste by boosting a key enzyme, scientists hoped that high doses of this everyday cough remedy might act as a shield to protect brain cells from damage. For fifty-two weeks, participants took either a high dose of oral ambroxol or a dummy pill called a placebo. The primary test used to measure success was the Montreal Cognitive Assessment, which is a standard check of memory, attention, and language. The short answer to whether ambroxol failed is yes, when looking at its ability to protect thinking and memory. Over the course of the year, those taking the cough medicine did not show any cognitive improvement compared to those on the placebo. When researchers adjusted the results for factors like sex, how long they had the condition, and the specific type of genetic variant, the cognitive scores for the group taking ambroxol were actually slightly worse than the placebo group. Despite this disappointment, the trial was not a complete loss. The researchers noticed an unexpected benefit. People taking ambroxol were able to reduce their daily dose of levodopa, which is the main medication used to manage movement symptoms. On average, the ambroxol group needed about one hundred and ten milligrams less levodopa per day than the placebo group. This levodopa-sparing effect suggests that ambroxol might still have some impact on how the brain processes movement chemicals, even if it does not protect cognitive function. Because of this curious finding and the fact that the medicine was highly tolerable, researchers are not giving up on the pathway. Instead of a simple failure, this study has turned a page, showing that while ambroxol might not be the cognitive shield everyone hoped for, it still has biological effects that warrant deeper investigation. How the Italian study compares to the British ASPro-PD study Now that the Italian results are public, everyone is asking: what does this mean for the ASPro-PD trial in the UK? Led by Professor Anthony Schapira at University College London (UCL), the ASPro-PD trial is another highly anticipated study testing ambroxol. If you are worried that the disappointing news from Italy means the British trial is bound to fail, it helps to look at how different these two studies actually are. Size of the study: The Italian study was a relatively small phase two trial with only sixty-five participants. The British study is a much larger phase three trial aiming to recruit three hundred and thirty people—more than five times the size of the Italian group. Length of the trial: The Italian trial followed patients for one year (fifty-two weeks). The British trial is twice as long, tracking patients for two full years, plus a six-month extension. What they are measuring: This is the most critical difference. The Italian trial focused on cognitive decline, meaning they wanted to see if the drug protected thinking, memory, and language. The British trial is focused on motor symptoms, meaning they are measuring physical movement, balance, and motor control using a standard rating scale called the MDS-UPDRS Part III. Who can participate: The Italian study only allowed people who carry the GBA1 genetic variation. The British study is wider, split almost down the middle: about half of the participants carry the GBA1 variation, and the other half do not. How they find participants: While the Italian study used traditional recruitment at three clinical sites, the British study is using an online genetic screening platform called PD Frontline. This helps pre-screen people for genetic variants like GBA1 and LRRK2 before they even join the trial. Ultimately, the mixed results from the Italian study do not mean the British ASPro-PD trial is destined to fail; rather, they highlight why the UK trial is so essential. Because the Italian study was small and only tracked cognitive changes over a year, it was poorly equipped to measure physical benefits. In contrast, the ASPro-PD trial is five times larger, runs for twice as long, and specifically measures physical movement and motor symptoms. While the Italian trial successfully proved that high-dose ambroxol is safe and hinted at a helpful "levodopa-sparing" effect for movement, the definitive answer on whether ambroxol can actually slow down the physical progression of Parkinson's rests entirely on the ongoing, more robust UK study.