Key messages

• Many people who have Parkinson's disease develop swallowing disorders, known as 'oropharyngeal dysphagia' or just 'dysphagia'. This condition can cause serious health problems, increase the risk of death, and reduce people's quality of life.

• We do not know if various types of rehabilitation for dysphagia help people with Parkinson's disease to swallow more effectively and safely because the evidence is limited and of poor quality.

• We need larger, high-quality studies to help us understand which, if any, rehabilitation treatments work best.

What is oropharyngeal dysphagia?

Oropharyngeal dysphagia (hereafter referred to as ‘dysphagia’) is a swallowing problem in which it is difficult or unsafe to move food or drink from the mouth through the throat and into the stomach.

Up to 80% of people with Parkinson’s disease develop dysphagia because the disease affects brain regions that control movement, weakening and slowing the muscles involved in swallowing. As a result, food or drink may not move smoothly into the stomach and can sometimes enter the airway instead of the oesophagus (food pipe).

Dysphagia can lead to serious health problems, including malnutrition and aspiration pneumonia (when food or drink is inhaled into the airway or lungs), increase the risk of death, and reduce quality of life.

How is dysphagia treated in people with Parkinson's disease?

In people with Parkinson's disease, dysphagia is usually treated first with medicines that aim to improve the symptoms of Parkinson’s disease overall. If swallowing problems continue, rehabilitation treatments may be used to try to make swallowing safer and easier. These include:

• exercises to strengthen the breathing or swallowing muscles;

• changes to head or body position during eating and drinking;

• changes to food and drink textures;

• stimulation treatments, which use safe, gentle medical devices to deliver electrical or magnetic stimulation to the brain or the nerves and muscles involved in swallowing, with the aim of helping activate and improve swallowing.

What did we want to find out?

We wanted to know if rehabilitation interventions for oropharyngeal dysphagia (swallowing disorders) help people with Parkinson's disease to swallow food and drink more effectively and safely.

What did we do?

We searched for studies that compared any type of rehabilitation treatment (as a single treatment or combined with another form of rehabilitation or medicine) to:

• no treatment;

• usual care (standard care that people with Parkinson's disease and dysphagia receive);

• 'sham' rehabilitation, where the treatment is fake;

• an inactive treatment, known as a 'placebo';

• another type of dysphagia rehabilitation.

We limited our focus to adults (18 years and older) with Parkinson's disease. We were interested in the effects of treatment on:

• swallowing efficiency and safety;

• dysphagia severity;

• quality of life;

• breathing issues;

• unwanted or harmful events (known as 'adverse events').

We compared and summarised the results of the studies and rated our confidence in the evidence, based on factors such as study methods and sizes.

What did we find?

We found 18 studies involving 1216 people with Parkinson's disease. Four studies were conducted in the USA, five in Europe, and nine in the rest of the world. Participants' average age ranged from 58.8 to 76.2 years. Most participants were male. All studies compared rehabilitation treatments to usual care or sham/placebo treatments. Treatment durations varied widely, from as short as two weeks to as long as one year. The studies were conducted in hospitals and people's homes.

We classified the studies into two broad groups: (1) behavioural treatments and (2) stimulation treatments.

Ten studies explored behavioural treatments, such as expiratory muscle strength training (i.e. exercises aimed at strengthening the muscles we use to breathe out) and tongue strength training (i.e. exercises aimed at strengthening the tongue muscles).

Eight studies investigated one or more of a range of stimulation treatments, as follows:

• neuromuscular electrical stimulation, where a low-intensity electrical current activates the muscles (four studies);

• repetitive transcranial magnetic stimulation, where magnetic pulses are applied to the scalp to stimulate areas of the brain involved in swallowing (two studies);

• deep brain stimulation, where electrical signals are delivered to specific areas deep in the brain to help control movement problems in Parkinson’s disease (two studies);

• transcranial direct current stimulation, where a very weak electrical current is applied to the scalp to change brain activity (one study).

All studies assessed outcomes immediately after the treatment. Six studies also assessed outcomes at anywhere from one to 14 months after treatment.

Only twelve studies provided data suitable for analysis. The evidence was very uncertain about the effects of all the different rehabilitation treatments on our key outcomes of interest (i.e. swallowing efficiency and safety, dysphagia severity, quality of life, and breathing issues).

There was very limited information about unwanted or harmful events.

What are the limitations of the evidence?

The studies were generally small and of poor quality. Also, not all the studies provided information about participants, treatments, and outcomes. Consequently, we have very low confidence in the evidence.

How current is this evidence?

The evidence is current to 26 September 2025.