Many different factors can result in encephalopathy. Infection with a bacterium or virus may cause some forms of the condition. Some of the transmissible spongiform encephalopathies appear to be caused by sporadic mutations to proteins called prions in animals, specifically cattle, which are later eaten as meat. Despite the notoriety of these cases, only several hundred have occurred worldwide. Other causes include:

• Brain tumor or increased pressure in the skull
  
  
• Heredity (e.g., Gerstmann Straussler Scheinker disease)
  
  
• Lack of oxygen or blood flow to the brain
  
  
• Long-term exposure to toxic elements (e.g., drugs, industrial chemicals, radiation, etc.)
  
  
• Trauma
  
  
• Poor nutrition