Prader-Willi syndrome (PWS) is a complex genetic disorder caused by the loss of function of genes on chromosome 15 that are normally active on the paternal copy. It is one of the most common genetic causes of life-threatening obesity and presents with a distinctive combination of endocrinological, neurological, behavioural, and psychiatric features that require lifelong multidisciplinary clinical management.
The psychiatric and behavioural dimensions of Prader-Willi syndrome are among the most clinically challenging aspects of the condition — and are frequently the primary reason for referral to specialist psychiatric care in adolescence and adulthood.
PWS presents in two distinct clinical phases.
In infancy and early childhood: severe hypotonia, feeding difficulties, failure to thrive, developmental delay, and hypogonadism.
From childhood onward: the clinical picture shifts dramatically. The central feature is hyperphagia — an insatiable, compulsive drive to eat caused by hypothalamic dysfunction affecting satiety signalling. Without strict environmental control of food access, individuals with PWS are at risk of life-threatening obesity. Hyperphagia in PWS is not a behavioural choice or lack of willpower — it is a neurobiological drive, and understanding this is critical for both clinical management and family support.
Beyond hyperphagia: intellectual disability of varying severity, learning difficulties, speech and language delays, emotional and behavioural dysregulation, and a specific psychiatric profile that distinguishes PWS from other intellectual disability syndromes.
Obsessive-compulsive features are extremely common — rigid routines, need for sameness, repetitive questioning, and compulsive skin picking. These overlap phenomenologically with OCD but have a distinct neurobiological substrate and may respond differently to treatment.
Emotional dysregulation — sudden, intense outbursts of anger or distress disproportionate to the triggering event. These episodes are related to the underlying neurological profile, not intentional behaviour.
Psychotic episodes occur in a significant proportion of individuals with PWS, particularly in adolescence and young adulthood, and more commonly in those with the maternal disomy (UPD) genetic subtype. Onset is often acute and can be dramatic.
Affective disorders — depression and presentations resembling bipolar disorder — occur at elevated rates compared to the general population.
Anxiety is common, often expressed through rigidity, compulsive behaviours, and distress when routines are disrupted.
The psychiatric presentation of PWS requires careful differential diagnosis and a treatment approach that accounts for the specific neurobiological context — including particular pharmacological sensitivities of this population.
Psychiatric assessment of individuals with Prader-Willi syndrome at IsraClinic is conducted within a comprehensive framework that accounts for the cognitive and communicative profile of the patient, involves the family or caregivers as central informants, and addresses the full psychiatric picture — OCD-related features, emotional dysregulation, mood disturbance, and psychotic symptoms where present.
Assessment also considers the significant impact of the syndrome on the family system — including the burden of food access management and the long-term planning considerations families navigate.
IsraClinic provides specialist psychiatric evaluation, second opinion on existing diagnoses and treatment plans, pharmacological management, and guidance for families and caregivers.
Dr. Karny Jabotinsky-Rubin, Senior Medical Expert at IsraClinic, is the author of a scientific publication specifically addressing behavioural disturbances in Prader-Willi syndrome — contributing to the clinical evidence base for risperidone in the management of behavioural symptoms in this population. Full publication list available on PubMed.
Pharmacological treatment of the psychiatric features of PWS requires particular care and expertise. This population has specific sensitivities to certain medications, and standard adult psychiatric protocols may not apply.
Antipsychotic medications — including risperidone — have evidence for managing severe behavioural disturbances in PWS. SSRIs may be used for OCD-related features and affective symptoms. Mood stabilisers may be indicated where affective dysregulation is prominent. All pharmacotherapy is prescribed individually and monitored carefully. Digital prescriptions are issued through the Yarpa system.
Psychotherapeutic and behavioural interventions — adapted to the individual's cognitive profile — can support emotional regulation, reduce anxiety, and improve quality of life. Family guidance and caregiver support are essential components of management.
Specialist psychiatric assessment is indicated when psychiatric symptoms are present or emerging; when existing treatment is not achieving adequate symptom control; or when families are seeking a second opinion on diagnosis or management.
IsraClinic accepts patients for in-person consultation in Tel Aviv and online, in English, Russian and Hebrew. No referral is required.
Clinical Reviewer: Dr. Karny Jabotinsky-Rubin, MD, MSc, BSc — Senior Psychiatrist | IsraClinic | Last reviewed: 2026
Prader-Willi syndrome requires specialist psychiatric expertise — particularly for families navigating behavioural and psychiatric challenges. Our team is available in English, Russian and Hebrew.