Toward a Reliable Distinction Between Patients with Mild Cognitive Impairment and Alzheimer-Type Dementia Versus Major Depression

BackgroundCerebrospinal fluid (CSF) levels of soluble amyloid precursor protein (sAPP) and its α-secreted form (α-sAPP) were investigated as a means to distinguish between individuals with mild cognitive impairment (MCI) and Alzheimer-type dementia (DAT) and those with major depressive episode (MDE) showing secondary memory deficits.MethodsTwenty-seven patients with MCI, 32 with probable DAT, and 24 with MDE attending a memory clinic were studied. Cerebrospinal fluid levels of sAPP/amyloid precursor-like protein 2 (APLP2) and α-sAPP were detected by Western blotting.ResultsPatients with MDE had the highest CSF levels of total sAPP/APLP2 as compared with MCI and DAT patients (p < .001); sAPP/APLP2 levels were higher in MCI than in DAT subjects. Whereas α-sAPP levels did not differ between the MCI and DAT groups, median levels of this peptide were significantly lower in MCI and DAT versus MDE patients.ConclusionsSoluble amyloid precursor protein/APLP2 and α-sAPP concentrations in CSF can differentiate between DAT and MCI versus MDE, facilitating early ameliorative interventions and appropriate treatment regimens.