What is Parkinson’s disease?
Parkinson’s disease is a progressive neurological condition in which nerve cells in a part of the brain called the substantia nigra gradually die. These cells produce dopamine, a chemical messenger that helps control movement. As dopamine falls, movement becomes slower and harder to control. Other brain systems are affected too, which explains many non-movement symptoms. The NHS Parkinson’s disease guide offers a full overview.
Symptoms
Movement (motor) symptoms
- Tremor, often in one hand at rest
- Slowness of movement (bradykinesia)
- Muscle stiffness (rigidity)
- Balance problems and shuffling walk, later in the disease
Non-motor symptoms
- Loss of smell, often years before diagnosis
- Constipation
- Sleep problems, including acting out dreams
- Low mood, anxiety and apathy
- Memory and thinking changes
- Dizziness on standing, bladder problems
Causes
Most cases have no single cause. Risk factors include age, male sex, some gene variants (such as LRRK2 and GBA), and environmental exposures such as certain pesticides and head injury. A clumped protein called alpha-synuclein builds up inside affected cells.
Diagnosis
Diagnosis is clinical, made by a neurologist based on symptoms and examination. Tests help exclude other conditions:
| Test | Purpose |
|---|---|
| Neurological examination | Identifies the core movement features |
| Response to levodopa | Good response supports the diagnosis |
| MRI brain | Rules out stroke, tumour or other causes |
| DaTscan (SPECT) | Shows loss of dopamine transporters in uncertain cases |
| Alpha-synuclein skin or spinal fluid tests | Newer biomarker tests available in some centres |
The diagnosis can be uncertain early on, and conditions like multiple system atrophy or progressive supranuclear palsy can look similar. If you want an independent opinion on your records, you can send your reports and imaging for a doctor review.
Standard treatment first
Parkinson’s medicines and therapies are effective at controlling symptoms for many years.
- Levodopa (with carbidopa or benserazide): the most effective symptom treatment.
- Dopamine agonists: pramipexole, ropinirole, rotigotine.
- MAO-B inhibitors and COMT inhibitors to extend levodopa effect.
- Advanced therapies: continuous levodopa infusions, apomorphine pumps.
- Deep brain stimulation (DBS): surgery that can reduce motor fluctuations and tremor in selected patients.
- Focused ultrasound for tremor in some centres.
- Exercise, physiotherapy, speech and occupational therapy: strongly recommended at every stage.
No current treatment has been proven to slow the underlying disease. That is why research into cell therapy draws so much interest.
Stem cell research in Parkinson’s
| Approach | How it works | Stage of evidence |
|---|---|---|
| Dopamine neurons from embryonic stem cells (e.g. bemdaneprocel) | Cells implanted into the brain by neurosurgery to replace lost dopamine cells | Phase 1 results published in Nature, 2025 (Tabar et al.); larger trials ongoing |
| Dopamine neurons from induced pluripotent stem cells (iPSCs) | As above, from reprogrammed adult cells | Phase 1/2 Kyoto trial published in Nature, 2025 (Sawamoto et al.) |
| Fetal tissue transplants | Older approach; mixed results and side effects such as graft-induced dyskinesia | Historic trials; TRANSEURO study |
| Mesenchymal stromal cells (MSCs) | IV or other infusion; thought to act through anti-inflammatory signals | Small phase 1 studies, mainly safety; no proven benefit |
What the 2025 trials mean
The 2025 studies were important milestones: they showed that lab-made dopamine neurons could be implanted with acceptable short-term safety, and imaging suggested the cells survived. But the trials were small, open-label and early. They do not yet show that the treatment works better than placebo surgery. These products are only available through regulated clinical trials.
Mesenchymal stem cells
MSC-based stem cell therapy is the type usually offered outside trials. MSCs do not become dopamine neurons. Small studies, such as a phase 1 trial of intravenous allogeneic MSCs (Schiess et al., Movement Disorders, 2021), focused on safety. Any reported improvements need confirmation in controlled trials. The evidence level is low.
Regulatory status
No stem cell therapy is approved for Parkinson’s by the US FDA, the Australian TGA or the UK MHRA. The FDA warns about unapproved stem cell therapies. Patients in Australia, the UK and the US can search for trials at ClinicalTrials.gov.
Who may be a candidate, and who should not
May be considered for an MSC-based or supportive program (after review):
- Confirmed Parkinson’s disease, under a neurologist
- Stable on medication
- Able to travel safely, with a carer if needed
- Clear understanding that this is experimental
Should not:
- Uncertain diagnosis or atypical parkinsonism without specialist review
- Significant dementia limiting informed consent without a legal representative
- Frequent falls or severe low blood pressure making travel unsafe
- Active infection or active cancer
- Anyone planning to stop or cut their Parkinson’s medicines
Risks
- Infusion reactions: fever, headache, fatigue
- Infection
- Rare blood clots
- Travel risks: missed medicine timings across time zones can worsen symptoms (plan doses carefully)
- Falls in unfamiliar surroundings
- Unknown long-term effects
Cells are prepared in ISO 9001:2015-certified partner laboratories.
What a Bangkok program looks like
- Send your records. Neurologist letters, medication list with timings, and any MRI or DaTscan.
- Doctor review. An honest opinion, including whether a clinical trial is a better choice.
- Assessment on arrival. Examination and safety tests.
- Program, which may combine an MSC infusion with physiotherapy and supportive care such as our longevity program or NAD+ IV therapy, clearly labelled as supportive.
- Summary for your neurologist.
See how it works. Related reading: stroke recovery.
Aftercare
- Keep exact medication timings
- Rest after infusion; avoid heat exhaustion
- Continue exercise: it is one of the best-supported interventions in Parkinson’s
- Report fever or new neurological symptoms promptly
- Keep regular reviews with your neurologist
Sources
- NHS: Parkinson’s disease
- Tabar V, et al. Phase I trial of hES cell-derived dopaminergic neurons for Parkinson’s disease. Nature, 2025.
- Sawamoto N, et al. Phase I/II trial of iPS-cell-derived dopaminergic cells for Parkinson’s disease. Nature, 2025.
- Schiess M, et al. Allogeneic bone marrow-derived mesenchymal stem cell safety in idiopathic Parkinson’s disease. Movement Disorders, 2021.
- U.S. FDA: Consumer Alert on Regenerative Medicine Products Including Stem Cells and Exosomes
Frequently asked questions
Is there a stem cell cure for Parkinson's?
No. No stem cell treatment has been shown to cure or stop Parkinson's disease. Research into transplanted dopamine-producing cells is promising but is still in clinical trials.
What did the 2025 Parkinson's stem cell trials show?
Two small studies published in Nature in 2025 implanted dopamine nerve cells made from embryonic stem cells or induced pluripotent stem cells into the brains of people with Parkinson's. They reported acceptable safety and signs of cell survival. They were not designed to prove benefit, and larger trials are under way.
Are the brain-implant cells the same as clinic stem cell infusions?
No. Trial products are specially made dopamine neurons placed into the brain by neurosurgery. Clinic-based therapies typically use mesenchymal stromal cells given by intravenous drip, which do not become dopamine neurons and have much weaker evidence.
Can I stop levodopa after stem cell therapy?
No. Never reduce or stop Parkinson's medicines without your neurologist. Abrupt withdrawal can cause severe symptoms and, rarely, a dangerous reaction similar to neuroleptic malignant syndrome.
Can NAD+ therapy help Parkinson's?
NAD+ and related compounds are being studied in Parkinson's, with small early trials of oral NAD precursors. Evidence is preliminary, and IV NAD+ is not a proven Parkinson's treatment.
How do I know if a program is worth considering?
Send your neurologist letters, medication list and any brain imaging on WhatsApp. A doctor will review them and give an honest view, including whether a clinical trial would be a better option.
This page is general information, not medical advice, and does not replace a consultation with your own doctor. Results vary and no treatment outcome can be guaranteed. We are a patient coordination service and may receive a referral fee from partner medical providers. See our medical disclaimer and referral disclosure.