Which biomarker is used in Lewy Body Dementia diagnostic criteria?

• A. Reduced dopamine transporter uptake in basal ganglia by PET or SPECT
• B. Elevated tau in CSF
• C. Amyloid PET positivity
• D. Increased CSF 14-3-3 protein

Answer: (B)

Lewy body dementia diagnosis relies on evidence of Lewy-type neurodegeneration, which includes a hallmark finding: reduced dopamine transporter uptake in the basal ganglia detected by DAT imaging (PET or SPECT). This pattern reflects loss of presynaptic dopaminergic neurons in the nigrostriatal pathway caused by Lewy body pathology, and it strongly supports the diagnosis within the Lewy spectrum.

Elevated tau in cerebrospinal fluid is more characteristic of Alzheimer's disease and other tauopathies, not the Lewy body pathology itself. Amyloid PET positivity indicates amyloid plaque deposition, which can be present in Lewy body dementia but is not specific to it and does not by itself establish the diagnosis. Increased CSF 14-3-3 protein points to prion diseases like Creutzfeldt-Jakob disease rather than Lewy body pathology.

So the biomarker used in Lewy body dementia diagnostic criteria is the reduced dopamine transporter uptake in the basal ganglia on DAT imaging, reflecting the nigrostriatal dopaminergic degeneration central to Lewy body disease.