Expression and Genotype Are Possible Discriminators in Different Forms of Dementia.

Vascular alterations often overlap with neurodegeneration, resulting in mixed forms of dementia (MD) that are hard to differentiate from Alzheimer's Disease (AD). The 26 bp intergenic polymorphism of , a key component of SNARE complex, as well as its mRNA and protein levels are associated with neurological diseases. We evaluated and 26 bp Ins/Del genotype distribution in 177 AD, 132 MD, 115 Mild Cognitive Impairment (MCI) and 250 individuals without cognitive decline (CT), as well as gene expression in a subset of 73 AD, 122 MD, 103 MCI and 140 CT. Forty-two MCI evolved to AD (22 MCI-AD) or MD (20 MCI-MD) over time. mRNA was higher in MD compared to AD ( = 0.0013) and CT ( = 0.0017), and in MCI-MD compared to MCI-AD ( < 0.001) after correcting for age, gender, MMSE and +/- covariates ( = 0.004). A higher expression was observed in subjects carrying the minor allele Del compared to those carrying the Ins/Ins genotype ( = 0.012). Finally, Del/Del genotype was more frequently carried by MD/MCI-MD compared to CT ( = 0.036). These results suggest that mRNA expression can discriminate mixed form of dementia from AD, possibly being a biomarker of AD evolution in MCI patients.