Approach 3 of 6
Help cells clean up
Can we fix the cell's recycling and power?
57 steps since 1987. 10 moved us forward. Antioxidants and energy boosters did not work. Ambroxol, a cough medicine, is in a final-stage trial, ASPro-PD, due in 2029. A smaller ambroxol trial in gene carriers did not help. As of Oct 2026
Facts on this page checked 18–22 Oct 2026
Each dot is one step in this approach: a discovery, a new tool or a trial, by the year it started.
- 10 moved us forward
- 4 waiting for results
- 27 still open
- 3 overtaken by better ideas
- 13 dead ends
Where it stands
- How far it has got
- Step 4 of 5 · Final large trials
- Has it slowed Parkinson's?
- Not yet shown
- Tried and did not work
- 11 trials
- Next result
- Dec 2026N-DOSE · Phase 2
The idea in brief
Every cell has "power plants" and "recycling bins". The power plants, called mitochondria, make the energy a cell runs on. The recycling bins, called lysosomes, break down worn-out parts and waste.
In Parkinson's, both seem to go wrong. In 1989, scientists found that the power plants in Parkinson's brains work poorly. In 2009, they found that changes in a gene called GBA are the commonest inherited risk. This gene makes an enzyme that works inside the recycling bins. In that study, the odds of Parkinson's were about five times higher in people with a GBA change.
So researchers are trying two things. Some drugs try to help the recycling bins work better, such as ambroxol, a cough medicine. Others try to protect the power plants, or to clear the ones that are damaged.
A third idea blamed "rust" in cells, called oxidative stress. It was tested with antioxidants, which mop up rust-like damage. Most of these trials did not work. A few small studies are still running.
How we got here
- Power plants fail · 1989
- Antioxidant loss · 1994
- PINK1 and clean-up · 2004
- GBA gene risk · 2009
- GCase loop · 2011
What has been tried
Each row is one trial in people. Its dot shows how it turned out, using the same key as the chart above.
Results already in
25 trials
Grouped by the line of research they belong to. Open a group to see its trials.
Recycling bins and the GBA gene5 finished trials3 did not work2 mixed or early
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Venglustat · venglustat, a pill that cuts the raw material for the enzyme GCase
Did not work
No slowing in 221 gene carriers over a year. Scores were slightly worse than on placebo.
-
GBA gene therapy · gene therapy: one injection of a working GBA gene near the brain
Mixed or early results
An early safety trial. No results on benefit have been found. The first person treated had a serious immune reaction.
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AMBITIOUS · ambroxol, a cough medicine, at about ten times the cough dose
Did not work
No benefit for thinking in 65 gene carriers over a year. This is a preprint, not yet checked by other scientists.
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BIA 28-6156 · BIA 28-6156, a pill meant to raise the enzyme GCase
Did not work
No difference from placebo in 273 gene carriers over 18 months. The company has stopped work on it for Parkinson's.
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GT-02287 · GT-02287, a pill meant to restore the enzyme GCase
Mixed or early results
Company reports only. About 20 people took it, with no placebo group, so it cannot show benefit. Not yet checked by independent scientists.
Power plants13 finished trials4 did not work6 mixed or early2 passed a stage1 replaced
-
Coenzyme Q10, Phase 2 · coenzyme Q10, a supplement
Replaced by a newer approach
The highest dose looked slightly helpful in 80 people, but the result was weak. The later 600-person trial found no benefit.
-
MitoQ · mitoquinone, a pill that carries an antioxidant into mitochondria
Did not work
No difference from placebo in 128 newly diagnosed people over 12 months. It did not slow Parkinson's.
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Coenzyme Q10, QE3 · coenzyme Q10, a supplement
Did not work
No benefit in 600 people at two doses. Scores were no better than on placebo, and slightly worse. It was safe, but it did not work.
-
Creatine · creatine, a supplement
Did not work
No benefit in 1,741 people. The trial stopped early because creatine was not helping.
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EPI-589 · EPI-589, a pill meant to protect cells from oxidative stress
Mixed or early results
In 44 people, all taking the drug, there were no safety problems. With no placebo group, it could not show benefit.
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CNM-Au8 · CNM-Au8, a drink of gold nanocrystals, made by a company
Mixed or early results
In 13 people with no placebo group, a brain energy marker did not clearly change. It does not show any benefit.
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Terazosin pilot · terazosin, a prostate drug
Mixed or early results
It raised a brain energy marker in 13 people compared with placebo. Three on the drug stopped because of dizziness. Too small to test slowing.
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NADPARK · nicotinamide riboside, a form of vitamin B3
Passed this stage
Safe in 30 people over 30 days, and it raised NAD, a chemical cells use for energy. It was not built to test slowing.
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NR-SAFE · nicotinamide riboside, at three times the earlier dose
Passed this stage
Safe for four weeks in 20 people, with only mild side effects. It cannot show long-term safety or benefit.
-
UDCA · ursodeoxycholic acid (UDCA), an old liver drug
Mixed or early results
Safe in 30 people. A brain scan hinted at better energy use, but motor scores did not differ. Too small to show slowing.
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NOPARK · nicotinamide riboside, a form of vitamin B3
Did not work
No benefit in 410 people. After a year, scores were slightly worse than on placebo.
-
MTX325 and ABBV-1088 · pills meant to restart the clearing of damaged mitochondria
Mixed or early results
Early safety tests only. There are no results on whether they help.
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TJ0113 · TJ0113, a pill from a Chinese company
Mixed or early results
The company reports a large gain in movement scores over 12 weeks in 149 people. It is short, not yet peer reviewed, and may be symptom relief.
Fighting "rust" (antioxidants)7 finished trials4 did not work1 mixed or early2 replaced
-
DATATOP · deprenyl, a pill, and vitamin E
Replaced by a newer approach
In 800 people, vitamin E did nothing. Deprenyl delayed the need for levodopa, but this probably came from easing symptoms, not slowing the disease.
-
TEMPO · rasagiline, a pill
Replaced by a newer approach
Starting early left 404 people better off than starting late. But the design could not prove this was slowing the disease, not symptom relief.
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ADAGIO · rasagiline, a pill
Did not work
In 1,176 people, one dose hinted at slowing but the other showed nothing. In 2011 a US expert panel voted 17 to 0 that slowing was not proven.
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Nasal glutathione · glutathione, the brain's own antioxidant, as a nose spray
Mixed or early results
Everyone improved, including people on placebo, so it showed no benefit over placebo in 45 people. One person on the high dose had a heart problem.
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Hydrogen water · water with hydrogen gas dissolved in it
Did not work
A pilot in 17 people looked good. A larger trial in 178 people found no difference from placebo.
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SURE-PD3 · inosine, a pill that raises urate, a natural antioxidant in blood
Did not work
Urate rose as planned, but Parkinson's did not slow in 298 people. Kidney stones were more common on inosine.
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FAIRPARK-II · deferiprone, a pill that removes iron
Did not work
Symptoms got worse, not better, in 372 newly diagnosed people. Iron fell as planned, so the drug reached its target and still did harm.
Still to come
4 trials · dates are expected, not promised
The next result is due in Dec 2026, from N-DOSE. The largest trial still to report, ASPro-PD, is expected in Feb 2029.
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N-DOSE · nicotinamide riboside, a form of vitamin B3, at three doses
Result due Dec 2026
Will tell us which dose raises brain NAD most reliably. It cannot show slowing. It finished in April 2025 and no result has been found.
Who: Adults with Parkinson's; the registry has the details · Last checked 22 Oct 2026
Details and sources: N-DOSE Check if it is recruiting: N-DOSE
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NAC · N-acetylcysteine (NAC), a supplement that helps the body make glutathione
Result due Jan 2027
Will tell us whether a brain-scan change seen in small trials without placebo holds up. Even a good result would not show slowing.
Who: People with Parkinson's. This study plans 50 people and compares NAC with a waitlist. · Last checked 22 Oct 2026
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NOSE-PD · a nasal spray of insulin plus glutathione
Result due Nov 2027
Will tell us whether adding insulin helps thinking skills, measured by a word test at 24 weeks. It would not show slowing.
Who: People with Parkinson's. This study plans 56 people, with the spray as an add-on. · Last checked 18 Oct 2026
Details and sources: NOSE-PD Check if it is recruiting: NOSE-PD
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ASPro-PD · ambroxol, a cough medicine
Result due Feb 2029
Will tell us whether ambroxol slows Parkinson's over two years in 330 people, with and without a GBA gene change.
Who: People with Parkinson's in the UK, aiming for equal numbers with and without a GBA gene change. · Last checked 19 Oct 2026
Details and sources: ASPro-PD Check if it is recruiting: ASPro-PD
In words
Of the 29 trials in people, 11 did not work, 2 passed their first stage, 9 had mixed or early results, 3 were replaced by newer approaches, and 4 have results due. The first is due in Dec 2026; the largest, ASPro-PD, in Feb 2029.
What the dead ends taught us
- Hitting the right gene is not enough. Three drugs aimed at GBA did not help people who carry a GBA change. They were venglustat, BIA 28-6156 and high-dose ambroxol. The ambroxol result is not yet checked by other scientists. (Venglustat; BIA 28-6156; AMBITIOUS)
- Mopping up "rust" did not slow Parkinson's. Coenzyme Q10, creatine, MitoQ, inosine and hydrogen water did not work. (Coenzyme Q10, QE3; Creatine; MitoQ; SURE-PD3; Hydrogen water)
- Hitting the target can still do harm. Deferiprone removed iron as planned, yet symptoms got worse. Nicotinamide riboside raised a cell energy chemical, yet people did slightly worse than on placebo. (FAIRPARK-II; NOPARK)
- A small early result often does not hold up. Coenzyme Q10 and hydrogen water both looked helpful in small trials. Larger trials then found no benefit. (Coenzyme Q10, Phase 2; Coenzyme Q10, QE3; Hydrogen water)
- Easing symptoms can look like slowing the disease. Deprenyl and rasagiline delayed the need for other drugs, but this did not prove they slow Parkinson's. (DATATOP; TEMPO; ADAGIO)
Most drugs tested for any brain disease do not work, and each failure rules something out.
What it would mean for you
If one of these approaches works, it would aim to slow Parkinson's down. It would not bring back brain cells that are already lost. A GBA drug might help only gene carriers, but the ambroxol trial below also tests people without a GBA change.
The biggest test is ASPro-PD, a final-stage trial of ambroxol in 330 people. It is expected to report in Feb 2029, but expected is not promised, and trials often run late. Even with a good result, approval would take further time. Most drugs here are pills. The gene therapy GBA gene therapy is one injection near the brain, given with drugs that calm the immune system.
Many other drugs here are at the safety stage. Passing a safety test means a drug is safe enough to test further. It does not mean it works. Some results come only from companies, such as TJ0113 and GT-02287. These are small, and have not been checked by independent scientists.
Should I try this now?
No. None of these treatments has been shown to slow Parkinson's. Do not buy supplements sold to boost cell energy or fight "rust". This includes coenzyme Q10, creatine, nicotinamide riboside and N-acetylcysteine (NAC). Large trials of the first three found no benefit, and nicotinamide riboside did slightly worse than placebo. NAC has only small studies, with no placebo group. (Coenzyme Q10, QE3; Creatine; NOPARK; NAC)
Do not treat yourself with ambroxol either. In some countries it is sold as a cough medicine. Trial doses are much higher than cough doses. Trial volunteers also get safety checks that you would not get at home. Talk to your neurologist first.
Can I take part?
Each trial sets its own rules. ASPro-PD looks for people in the UK, both with and without a GBA change. Some trials look for people with a GBA change, and ask for a gene test first. Others look for people with early Parkinson's.
Related approaches
Sources, and the same lanes for researchers
This page is built from 58 research landmarks. Each has its own sources; follow "Details and sources" on any trial. Facts were checked 18–22 Oct 2026. The summary was written on 22 Oct 2026.
- Lysosome & GBA (18 landmarks)
- Mitochondria & energy (27 landmarks)
- Oxidative stress (13 landmarks)
- See these lanes on the full map
How this project checks its facts · Report an error on this page