2 Neuroscience2.13 Neurodegeneration
2.13.10 Cognition in motor neurone disease
2 min read
Written by Resident Doctor Committee · Published
New in the 2027 syllabus
The College added this topic for exams from January 2027.
What it is
Amyotrophic lateral sclerosis (ALS) damages both upper and lower motor neurones, but some patients also develop changes in thinking or behaviour.
ALS and frontotemporal dementia form one overlapping spectrum. A patient can have real cognitive or behavioural impairment without meeting criteria for dementia.
Why it happens
The frontal and temporal networks support executive control, language, motivation and social behaviour. When the disease affects them, symptoms appear that go beyond weakness.
Many cases of ALS and frontotemporal degeneration share the same pathology: abnormal TAR DNA-binding protein 43 (TDP-43). The C9orf72 repeat expansion is one genetic cause shared by both.
How it presents
Domain | Possible presentation |
|---|---|
Executive function | Trouble switching plans, organising tasks or holding back responses |
Language | Less fluent speech, word-finding problems or grammatical errors |
Social cognition | Trouble reading other people's intentions or emotions |
Behaviour | Apathy, disinhibition, rigidity or reduced empathy |
Emotional expression | Involuntary laughing or crying that may not match how the person actually feels |
Assessment and pitfalls
Allow for physical disability. Weakness and speech problems can lower scores on standard cognitive tests when cognition has not declined. Adapt testing to these limitations.
Use an ALS-specific screen, such as the Edinburgh Cognitive and Behavioural ALS Screen. It covers the relevant domains and allows for physical disability.
Take a collateral history. Family or carers may notice changes in judgement, motivation and how the person relates to others that the person does not report.
Pseudobulbar affect (involuntary laughing or crying) is not the same as depression. Tell them apart, but both can be present together.
Communication difficulty does not by itself show loss of decision-making capacity. Give the person an accessible way to communicate and assess capacity for the specific decision.
Cognitive or behavioural change can affect understanding of treatment, engagement and what support the family needs, so manage it as part of multidisciplinary care.