Variant CJD (vCJD) is an acquired TSE caused by transmission of the agent responsible for bovine spongiform encephalopathy (BSE) in cattle. Whereas sporadic CJD is most common in people over 50 and accounts for 85% of CJD cases, vCJD has an age of onset in the late 20s.
Sporadic CJD presents as rapidly progressive dementia with a range of neurological signs and symptoms, including ataxia, myoclonus, visual disturbances and movement disorders. In vCJD, this presentation is often preceded by psychiatric symptoms, such as anxiety and depression.
People with vCJD tend to live for an average of 14 months after symptom onset, while survival for sporadic CJD is frequently only a few months.