Final answer:
Creutzfeldt-Jakob disease (CJD) is a type of spongiform encephalopathy that affects human beings and leads to dementia. It is caused by misfolded infectious prion proteins, resulting in the formation of abnormal proteins in the brain and subsequent neurological symptoms.
Step-by-step explanation:
The type of spongiform encephalopathy that affects human beings and leads to dementia is called Creutzfeldt-Jakob disease (CJD). CJD is a degenerative, fatal neurological disease caused by infectious misfolded prion proteins. It is characterized by the accumulation of abnormal proteins in the brain, resulting in the formation of neurofibrillary tangles and amyloid plaques. Symptoms include memory loss, personality changes, blurred vision, uncoordinated movements, and insomnia, which progressively worsen over time.