One SRM-based study in plasma reported increased levels of total ApoE in MCI compared with controls (126), but two other plasma and CSF studies of AD and controls found no significant group differences (127, 128), and neither did a large CSF study that included AD, PD, PD dementia, and DLB (129), neither for total ApoE levels. The gene discussed is APOE; the disease is Parkinson disease.