Synopsis
Confirm true loss of acquired skills, recognise time-critical epileptic, neurological, metabolic, neuromuscular and safeguarding causes, route referral by age and affected domain, and preserve function during urgent investigation.
- Regression is loss of a skill that was previously acquired and used reliably; delayed acquisition and temporary poor performance are different.
- Confirm the skill, duration of mastery, contexts in which it was used, date of last normal function and whether loss is continuous, episodic or task specific.
- Ask for videos, nursery or school observations and medication timelines; apparent regression may reflect hearing loss, pain, depression, sleep deprivation or environmental change.
- Acute loss is an ABCDE and neurological problem, not a routine developmental referral.
- NICE directs motor regression to paediatric neurodevelopmental or neurology services and advises CK consideration in boys before review.
- NICE autism guidance directs language or social regression under age 3 to the autism team, but language regression after 3 and motor regression at any age first to paediatrics or neurology.
- Infantile spasms may be subtle; suspected cases under age 2 need tertiary paediatric neurology input within 24 hours and rapid sleep EEG.
- EEG supports an epileptic diagnosis but a normal routine EEG does not exclude epilepsy; sleep or prolonged recording may be needed.
- MRI is guided by focal neurology, abnormal head growth, seizures, motor loss or suspected structural or neurodegenerative disease.
- Metabolic testing is highest yield with episodic decompensation, multisystem signs, abnormal movement, family history or loss during fasting and illness.
- Do not withdraw therapy or education while investigating; protect communication, mobility, swallowing, nutrition, sleep and family safety.
- Reassess trajectory closely because the pattern and newly affected domain often refine the diagnosis.
Key red flags
Loss over hours or days, altered consciousness, focal weakness, ataxia or new gait abnormality requires immediate acute assessment.
Clusters of brief flexor or extensor spasms, especially on waking, with loss of smiles, visual attention or motor progress may be infantile spasms.
Regression triggered by fasting or illness, recurrent vomiting, hypoglycaemia, acidosis, unusual odour, organomegaly or affected siblings suggests metabolic disease.
Motor loss with weakness, calf hypertrophy, Gowers manoeuvre, reduced reflexes, swallowing or breathing difficulty suggests neuromuscular disease.
Loss of language or social skills under age 3 requires autism-team referral; motor regression at any age and language regression after age 3 require paediatric or neurological assessment first.
A history inconsistent with injury, access to sedating medicines or toxins, fear, bruising or abrupt functional change raises safeguarding concerns alongside medical causes.
Investigation priorities
Confirm true loss, domain sequence, rate and triggers.
Localise the affected system and identify immediate danger or phenotype clues.
Management branches
A caregiver or professional reports that development has gone backwards.
- Identify the exact skill, how securely and how long it was used, the last normal date and settings affected.
- Seek video and nursery or school collateral, medication and illness timelines and distinguish loss from plateau or refusal.
- Map the first domain and spread, then set urgency from hours, weeks, episodic or progressive course.