7 Old age psychiatry7.4 Psychiatric aspects of physical disease
7.4.1 Neurodegeneration and psychiatric presentation
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Written by Resident Doctor Committee · Published
New in the 2027 syllabus
The College added this topic for exams from January 2027.
Huntington's disease
What it is
Huntington's disease is a neurodegenerative disorder with autosomal dominant inheritance. It is caused by an expanded cytosine-adenine-guanine (CAG) repeat in the huntingtin (HTT) gene.
How it presents
The clinical picture combines motor, cognitive and psychiatric changes. Psychiatric symptoms may appear before obvious chorea (brief, irregular, involuntary movements that seem to flow from one part of the body to another).
Onset can be later in life. A family history that looks negative does not rule out the diagnosis.
Domain | Features |
|---|---|
Movement | Chorea, poor coordination and difficulty swallowing; rigidity may develop |
Cognition | Slowed processing, poor planning, reduced flexibility, and wider decline later on |
Mood | Depression, irritability, anxiety and sometimes mania |
Behaviour | Apathy, impulsivity, perseveration and reduced awareness of their own difficulties |
Psychosis | Delusions or hallucinations in a minority |
Apathy means reduced motivation and a reduced ability to start things. Distinguish it from depression, from sedation and from simply being unable to do the task.
Assessment
Suicide risk: ask about depression, impulsivity and recent losses. Consider the impact of the diagnosis and of changing function.
Family: the diagnosis affects relatives, so offer genetic counselling. Predictive testing of an unaffected relative follows a specialist process of consent and support.
Shared management principles
Neurology and psychiatry should coordinate treatment. Medicines that reduce behavioural symptoms can worsen movement, add sedation or make swallowing harder.
Assess function: eating, communication, mobility, driving, finances, and whether the person can manage their own treatment.
Occupational therapy, physiotherapy and speech and language therapy work alongside psychiatric treatment. They address daily function, falls, communication and dysphagia (difficulty swallowing).
Support carers. Help them understand how irritability, apathy and cognitive change affect the person, so that not every difficult interaction is seen as deliberate behaviour.
Review over time. This helps separate disease progression from medication effects and from treatable physical or psychiatric illness.