Objective:

To phenotype the clinical features and investigation profile of sCJD in adults over 80 years. 

Background:

Sporadic Creutzfeldt-Jakob disease (sCJD) is a rapidly progressive neurodegenerative disease with public health implications. Mean age of onset is 68 years. Age-specific incidence declines after 80 years. This may arise from under-ascertainment or other biological features of the disease. Accurate characterisation of late-onset sCJD is important for early diagnosis, avoiding unnecessary investigations, and improving ascertainment for public health purposes.

Design/Methods:

We analysed all probable and definite sCJD cases identified by the UK National CJD Research & Surveillance Unit over a 10-year period (2011-2021). Individuals were grouped by age of onset. Clinical features and investigation profiles were compared. 

Results:

10.3% (123/1196) had an age of onset over 80. Median survival was shorter (3.2 vs 4.3 months; p<0.001). Pyramidal signs (48.3% vs 34.2%; p=0.008) and akinetic mutism (55.1% vs 33.2%; p<0.001) were more frequent. Psychiatric symptoms (26.3% vs 39.6%; p=0.01) and cerebellar signs (65.4% vs 78.6%, p=0.007) were less frequent. Cognitive impairment and myoclonus were highly prevalent regardless of age. Between age groups, the diagnostic sensitivity of CSF RT-QuIC (92.9% vs 91.9%, p=0.74) was comparable, EEG was superior (41.5% vs 25.4%; p=0.006), and MRI was inferior (67.8% vs 91.4%; p<0.001).

Conclusions:

Late-onset sCJD has distinct clinical features, shorter survival, and a different profile of investigation sensitivity. CSF RT-QuIC, MRI brain, and specialist CJD review is recommended in older adults with a rapidly progressive neurological disorder. Autopsy is valuable when the cause remains elusive.