A rare transmissible encephalopathy most prevalent between the ages of 50 and 70 years. Affected individuals may present with sleep disturbances, personality changes, ataxia; aphasia, visual loss, weakness, muscle atrophy, myoclonus, progressive dementia, and death within one year of disease onset. A familial form exhibiting autosomal dominant inheritance and a new variant CJD (potentially associated with bovine spongiform encephalopathy) have been described. Pathological features include prominent cerebellar and cerebral cortical spongiform degeneration and the presence of prions.