Final answer:
The marker for measuring Creutzfeldt-Jakob disease in cases of rapidly progressive dementia is the prion protein, with abnormal prion proteins being a key diagnostic indicator. The 14-3-3 protein is also a supporting marker for CJD diagnosis.
Step-by-step explanation:
The marker for measuring Creutzfeldt-Jakob disease (CJD) in cases of rapidly progressive dementia is the prion protein. This neurological disease is known as a type of transmissible spongiform encephalopathy (TSE) and involves the accumulation of abnormally folded prion proteins, which can lead to the characteristic sponge-like lesions in the brain. Detection of these abnormal prion proteins in tissue samples is a key indicator of CJD. The 14-3-3 protein in cerebrospinal fluid (CSF) is also a supporting marker for diagnosis. Techniques such as RT-QuIC are significant in aiding the effective early detection of the abnormal prion proteins.