Many family members who care for a person with Parkinson's disease ask: “My family member has never choked at meals. Does that mean swallowing is safe?” In fact the answer is often a surprise. It does not mean that.The most dangerous thing about swallowing difficulty in Parkinson's disease is that the whole process can be completely silent. Far fewer people feel that their swallowing is abnormal than are found to have abnormal swallowing on instrument testing. When food or fluid goes into the windpipe, it often does not trigger a protective cough at all, and neither the patient nor the carer knows. This article goes through the causes of swallowing difficulty in Parkinson's disease, the clinical warning signs of silent aspiration, the IDDSI grading system for food textures, swallowing training with evidence behind it, and how to manage drooling (sialorrhoea).
Why does Parkinson's disease cause swallowing difficulty?
Swallowing looks simple, but it is in fact a precise series of muscle coordination from the mouth to the oesophagus. Because Parkinson's disease damages the motor control functions of the brain, the whole swallowing “production line” is affected. Chewing and the tongue pushing food in the oral phase, the airway protection mechanism in the pharyngeal phase, and the muscle movement in the oesophageal phase can all go out of step. Two of the risk points are rather particular to Parkinson's disease.
Why is silent aspiration so common?
What makes it easy to let one's guard down about swallowing difficulty in Parkinson's disease is that the problem is seriously underestimated. There is often a very large gap between the patient's own feeling and the results of objective instrument tests.
Do not judge safety only by whether there is choking. Among patients who aspirate, about two thirds cannot cough at all. Not choking when eating therefore does not mean that swallowing is safe. To assess risk accurately, indirect warning signs in daily life have to be watched for, and a speech therapist needs to examine the patient professionally. Action should not wait until there is obvious choking.
How to recognise silent aspiration: indirect clues in daily life
Since silent aspiration does not cause obvious choking, carers need to learn to watch for indirect warning signs in the details of daily life. If any one of the following appears, a detailed assessment by a speech therapist should be arranged as soon as possible. Of course, these signs are only a prompt about risk, are not a clinical diagnosis, and cannot replace a professional examination.
- After eating or drinking, the voice becomes wet or gurgly, as if there is phlegm, or the patient often has to clear the throat.
- There is repeated fever with no other clear reason, or pneumonia or chest infection several times.
- Weight falls for no reason and the patient gets thinner and thinner, or appetite is clearly poorer.
- Each meal takes much longer than before, the patient easily feels tired or short of breath partway through, or has to swallow several times for each mouthful.
- Drooling increases, or the patient starts to refuse food and drinks of certain textures.
The risk and consequences of aspiration pneumonia
The medical community takes silent aspiration very seriously because it can lead to very serious complications. Aspiration pneumonia is one of the main causes of death in the late stages of Parkinson's disease, and the risk of these patients getting aspiration pneumonia is itself far higher than usual.
The goal of swallowing rehabilitation: swallowing training and texture modification of the diet are mainly meant to reduce the risk of aspiration, protect safety when eating and keep up quality of life, and are not meant to “cure” the decline in swallowing completely. Parkinson's disease is a degenerative condition, and swallowing function changes with the course of the disease. The focus of care is therefore to find problems early, review regularly and adjust the plan as the situation changes. The earlier this silent crisis is dealt with, the better the protection for the patient.
Introduction to the IDDSI grading of food textures
When a patient's swallowing safety is in the red, adjusting the texture of food and drinks (for example thickening drinks with thickening powder, or cutting food up or blending it to a purée) is a common response. Internationally the unified IDDSI (International Dysphagia Diet Standardisation Initiative) is widely used, and many hospitals and residential care homes in Hong Kong have also gradually introduced this grading system in recent years.
| IDDSI levels 0–4 (drinks) | Drinks are graded from level 0 (thin, like water) to level 4 (extremely thick, eaten with a spoon), to define how thick a drink is. |
| IDDSI levels 3–7 (foods) | Foods are graded from level 3 (liquidised or liquid food) to level 7 (regular food that is easy to chew), to distinguish how soft food is and how large the particles are. |
| Overlapping levels (3 and 4) | Levels 3 and 4 appear in the grading of both drinks and foods. This reflects that food texture is in fact a continuum, and professional judgement is needed in clinical practice to draw the line accurately. |
Do not prepare levels by looking at a chart yourself.Which level the patient should eat must be assessed individually by a speech therapist. If drinks are not thick enough there is still a danger of aspiration, but if they are too thick, the intake of water and nutrition is affected and the patient may lose appetite or refuse to eat. The amount of thickening powder, the texture of the cooked food and the feeding technique all have to be tailored to the patient's swallowing ability and reviewed regularly. The Division of Speech and Hearing Sciences at the University of Hong Kong has Chinese-language IDDSI teaching material for the public to refer to, but this material is only for general understanding and cannot replace a clinical diagnosis.
Expiratory muscle strength training (EMST)
Among the many “swallowing exercises”, the one with the strongest clinical evidence is expiratory muscle strength training (EMST). The patient trains the muscles of exhalation specifically through a breathing device that provides resistance. This training not only strengthens the force of the cough, which helps to clear foreign matter that has entered the airway, but also improves the lifting movement of the hyoid bone and larynx complex, and so protects swallowing safety directly.
Hold reasonable expectations of the effect of rehabilitation. Although high-level clinical evidence supports EMST as improving swallowing safety, the improvement is moderate and the patient has to keep practising to maintain the effect. This training also does not suit everyone. The resistance level of the trainer and the number of repetitions must be set and adjusted by a speech therapist after assessment, and patients and family members should not buy the equipment and follow along by themselves.
Everyday strategies for eating safely
Besides muscle training aimed at a particular problem, the setting and manner of eating in daily meals also affect swallowing safety. A speech therapist recommends the supporting strategies below according to the individual assessment of the patient. Family members should understand, though, that some techniques (such as the chin-down posture), although they have research support, do not suit all patients and must be viewed objectively.
- A proper eating position—Keep the upper body upright when eating, with the head and neck in the middle position. After the meal, the patient should stay sitting upright for a while, to prevent food from flowing back or staying in the throat.
- Small mouthfuls, eaten slowly—Each mouthful should not be too big, and the pace of eating should be slow. Only after a mouthful has been completely swallowed should the next be eaten, so that food does not build up in the throat.
- Concentrate on eating and reduce distraction—Do not talk, watch television or hurry the patient while eating. Distraction greatly raises the risk of aspiration.
- Eat in the medication “on” period—As far as possible, arrange meals for the time when dopamine medicines work best (when muscle control is better after taking medicine), because swallowing is then safer.
The chin-down posture (tilting the head slightly downward when swallowing) that is often mentioned among the public needs an objective look at its clinical evidence and limits.
A meta-analysis of 14 studies with 571 people found that the chin-down posture overall significantly lowers the risk of aspiration (mean difference MD = −1.35) (Li et al., 2024). However, this approach has two important limits. First, the research results reflect only the average effect for a group, which does not mean it works for every patient, and the existing data do not show which kind of patient benefits most. Second, if the patient has impaired cognition, it is usually hard to remember the instruction, and hard to keep the posture up throughout a whole meal. The chin-down posture is therefore only one possible supporting method. Whether it suits a patient, and which food texture should go with it, must be assessed individually by a speech therapist, and it should not be applied by oneself.
One more point should be added: simple bedside tests (such as watching how fast the patient drinks water) are not enough to predict accurately whether the patient is at risk of aspiration (Pflug et al., 2019). This finding confirms that swallowing problems must be assessed comprehensively and individually by a speech therapist, with instrumental examination when needed, and that no judgement should be made on one or two simple actions or by the naked eye alone.
Dealing with drooling (sialorrhoea)
Many family members find it troubling, even embarrassing, when the patient often drools, and wrongly think the patient is making “too much saliva”. In fact, when people with Parkinson's disease drool, the reason is usually not an increase in saliva production. It is that the patient swallows saliva spontaneously less often, and the head and neck tend to lean forward, so that saliva collects in the front of the mouth and then spills over.
Non-drug support from a speech therapist
- Using prompting techniques to teach the patient the habit of swallowing saliva regularly and on purpose.
- Helping to adjust head and neck position and sitting posture, to reduce drooling caused by the head leaning forward.
- Carrying out a full assessment of swallowing function, to understand the overall swallowing situation behind the drooling.
Medical items that need referral to a doctor
- Prescribing drugs such as anticholinergics to control saliva must be assessed and decided by a doctor.
- Injection of botulinum toxin into the salivary glands must be assessed and carried out in person by a doctor.
- The speech therapist helps with referral to a doctor as needed, and does not prescribe drugs or give injections.
Put simply, a speech therapist can guide non-drug swallowing cue training and posture adjustment. But anything involving prescribing drugs or injecting botulinum toxin falls in the doctor's professional field. If the drooling persists or is severe, the speech therapist refers the patient to a doctor for further assessment and does not use drugs by themselves.
How does home speech therapy support swallowing care in Parkinson's disease?
Handling swallowing problems in Parkinson's disease well depends largely on whether the process is safe and proper in the patient's real home setting, with everyday food, and when family members help with feeding. Home speech therapy can support exactly these daily details. The therapist can carry out a swallowing assessment on site using the dishes and utensils the patient normally eats, demonstrate safe feeding techniques to family members on the spot, guide carers on how to watch for the daily warning signs of silent aspiration, and adjust the IDDSI food texture and rehabilitation training plan flexibly as the condition changes. For families of people with Parkinson's disease who have limited mobility, are in the late stages, or need family members to learn feeding technique on the spot, a home visit service is especially suitable, and it also fills the gap in care while waiting for public healthcare services.
For another common speech difficulty in people with Parkinson's disease, a voice that gets quieter, and why LSVT LOUD therapy stresses practising “speaking louder” rather than simply pursuing “clear articulation”, see A quieter voice and LSVT LOUD. The coordination of the hands at mealtimes and the choice of anti-tremor utensils belong to the professional field of occupational therapy, which has a separate page on eating and anti-tremor utensils.