Overview

Prader-Willi Syndrome is a genetic disorder that affects a person physically, cognitively and behaviourally. Approximately 350,000 to 400,000 people worldwide have the condition.¹ 

One of the main features of Prader-Willi Syndrome is over-eating, also known as hyperphagia. Other symptoms include low muscle tone and poor feeding in the infant, short stature, delays in intellectual development, hypogonadism (deficient production of testosterone), and behavioural challenges. 

In this article, we look at Prader-Willi Syndrome and focus on the behavioural aspects of the condition and why it is important to manage this in terms of health and quality of life.

What is Prader-Willi syndrome?

Prader-Willi Syndrome is a genetic disorder that affects a person physically, cognitively and behaviourally. Around 350,000 to 400,000 people worldwide have the condition¹ and it affects all genders and ethnicities equally.² The syndrome was first described in 1956.³

Hyperphagia, also known as over-eating, is one of the main features of Prader-Willi Syndrome. Other symptoms include low muscle tone and poor feeding as an infant, which give rise to short stature, delays in intellectual development, and behavioural issues as the person gets older.⁴ 

At present, effective therapies addressing the behavioural challenges of the syndrome have not been developed. A limiting factor for therapeutic studies is the lack of agreement on how to accurately define and measure the complex features of the syndrome.⁵ 

Further difficulties arise from the nature of the behaviour and the difficulty of getting an individual to comply with a study activity. 

Causes of Prader-Willi Syndrome

Prader-Willi Syndrome is a relatively rare genetic disorder that occurs due to a defect on chromosome 15. It is not considered a hereditary disorder and it is believed to occur quite randomly. The cause of the genetic defect is not yet known. 

Behavioural challenges associated with Prader-Willi syndrome

The behavioural challenges associated with Prader-Willi Syndrome can vary and include:

•  Skin picking
• Teeth grinding
• Tantrums
• Obsessive tendencies
• Eating non-food items, also known as Pica
• Stealing food/money
• Non-compliance
• Anxiety
• Psychosis
• Aggression 

These behaviours can be present to varying degrees but all are detrimental to the health and well-being of the individual and their families or caregivers. 

Impact of behavioural challenges

Approximately 80% of individuals with Prader-Willi Syndrome exhibit severe temper outbursts into adulthood.⁶ The outbursts can last minutes to hours and are often followed by a “zoning out” period and a need to sleep. This suggests that the outbursts take an emotional and physical toll on the individual. These are difficult for families and caregivers to manage, especially when out in public. The families may need support to develop strategies for dealing effectively with these episodes. The outbursts are reported to have a significant impact on the quality of life of the individual and their family.⁷

Hyperphagia

Hyperphagia is present in all individuals with Prader-Willi Syndrome. This is defined as compulsive overeating over a prolonged period. Hyperphagia leads to increased weight and obesity. The extent of hyperphagia is not necessarily linked to the level of obesity but to a desire for food access.⁵

Cause of hyperphagia

Hyperphagia arises from an insatiable appetite and the cause is not fully understood. Hyperphagia is linked to many of the behavioural issues in Prader-Willi Syndrome, as the individuals want to eat compulsively and can have negative reactions to being prevented from eating. 

Psychiatric illness in Prader-Willi syndrome

There is a significant risk of psychiatric disorders with Prader-Willi Syndrome including anxiety, major depression and psychosis.⁸ A high proportion of people with Prader-Willi Syndrome suffer from anxiety. A recent study in Ireland showed that 29% of adolescents and 43% of adults with Prader-Willi Syndrome had anxiety and, whilst some of it was related to food access, there was also more generalised anxiety. The same study found that anxiety was the most common psychiatric disorder and that 30% of the study participants had at least one psychiatric symptom.⁹ 

Repetitive behaviours

Many people with Prader-Willi Syndrome exhibit repetitive questioning behaviour related to resistance to change. This can be very challenging for families and requires daily active behavioural management. It is thought that the repetitive questioning is a stress reaction due to the desire for food.¹⁰

Frequency and triggers to behaviours

The frequency of behaviours varies from one individual to another but triggers are often related to a desire to eat and the reaction to being prevented from doing so. 

Multidisciplinary approach to behaviour management

As Prader-Willi Syndrome affects many parts of the individual, a multidisciplinary approach to disorder management is necessary. There can be an entire range of health professionals involved in working with the caregivers and schools so that consistency of approach is optimised. However, even with an excellent diet, most people with Prader-Willi Syndrome will consistently be hungry and a preoccupation with accessing food can lead to anxiety and behavioural issues.

Ideally, families should have access to disciplines such as medicine, psychology, education, occupational therapy, and speech and language therapy. Unfortunately, services are generally not widely available locally. Furthermore, as every individual experiences a range of symptoms to a different extent, it is not possible to formulate a specific and all-encompassing treatment plan. Rather, treatment has to be tailored to the individual depending on their presenting issues.

Approaches to managing behaviour

Due to the wide range of behavioural problems and variability of symptom severity in Prader-Willis Syndrome, disorder management is age-dependent, multidisciplinary, and requires a problem-based approach to cater to each individual. Family members, caregivers, paediatricians, psychologists, dietitians, and speech-language therapists all play an important role in the management and treatment of symptoms in an individual. 

While there is no cure for Prader-Willi Syndrome, with early diagnosis and a proactive approach, individuals with the condition can live full and meaningful lives.¹¹

Behaviour management strategies

No specific behaviour management strategy has been confirmed for Prader-Willi Syndrome but the main focus is on curtailing the over-eating. This can involve physical restriction to the food including locked cupboards, locked kitchens and distraction techniques. Generally, the approaches to behaviour management should involve: 

• Reassuring the individual that food will be served at the right time
• Ensuring that they know that the wrong foods or extra foods will not be allowed
• Consistency
• Providing a routine
• Being firm
• Relaxation techniques
• Cognitive Behavioural Therapy (CBT)
• Distraction
• Avoid giving in to demands for more food 
• Sometimes locking cupboards, the fridge or the entire kitchen if necessary

Medications 

There are currently no effective medications for use in Prader-Willi Syndrome. Growth hormone therapy is the recommended standard treatment for children with Prader-Willi Syndrome because it has been found to improve body fat and lean body mass by increasing muscle mass and energy expenditure, linear growth and IQ development.¹²

After six months of treatment with the antidepressant medication Sertraline, 92.6% of individuals with Prader-Willi Syndrome either no longer displayed temper outbursts or displayed a decreased frequency and severity of temper outbursts. It was concluded that Sertraline may be a promising treatment option for severe temper outbursts in patients with Prader-Willi Syndrome.¹³ 

Let’s look at the positives

Now that we have looked at the negative aspects of the emotional/behavioural disturbances in Prader-Willi Syndrome, let us look focus on some positives. Caregivers in one study reported warmth (94%), persistence (41%), and skills (41%) in their family members with Prader-Willi Syndrome. This indicates that not all behaviours associated with Prader-Willi Syndrome have to be seen as negative. These positive aspects of behaviour in Prader-Willi Syndrome provide a more balanced view of the condition and a basis for holistic interventions.¹⁴

Considerations and limitations

No definitive treatment exists for people with Prader-Willi Syndrome and, with such variation in severity and extent of symptoms, treatment plans cannot be restricted to one size fits all. 

Support for individuals with Prader-Willi syndrome and their families

There are local and national support groups for families and individuals with Prader-Willi Syndrome such as the Prader-Willi Support Association UK, and several resources are available online, including on the NHS website. 

Summary

Prader-Willi Syndrome is a non-hereditary, complex genetic condition which affects the physical and cognitive development of individuals to different extents. The key issues include hyperphagia (which can lead to serious obesity), behavioural problems, and psychiatric illness. All these issues affect the well-being and life quality of individuals and their families.

A multidisciplinary approach is required to manage the disorder in affected individuals but there are currently no standardised treatments. 

Individualised and multidisciplinary treatment approaches should aim to manage negative behaviours and prevent overeating. 

Research is ongoing into behaviour management approaches and medications that may ultimately optimise the life quality and health of individuals with the condition.