Association of CSF apolipoprotein E, Aβ42 and cognition in Alzheimer’s disease

A significant association between CSF Aβ42 and cognition in patients with Alzheimer’s disease (AD) homozygous for the ε3 allele of the apolipoprotein E (apoE) has been described. In this study we extended our observations on apoE, as another plaque component, and investigated the association between CSF apoE concentrations and cognitive performance after stratification for the apoE genotype in 62 patients with AD, 19 other forms of dementia and 18 controls. CSF Aβ42 and apoE concentrations were significantly and positively associated with Mini Mental State Examination (MMSE) score in AD (Aβ42: r = 0.332; P = 0.026; apoE: r = 0.386; P = 0.006). For Aβ42 this association was exclusively present in ε3 homozygotes (r = 0.44; P = 0.014), whereas apoE was correlated with MMSE in ε4 hetero- or homozygotes subjects (ε4/εX: r = 0.638; P = 0.004: ε4/ε4; r = 0.812; P = 0.05). No association was observed between CSF concentrations of Aβ42 and apoE. The significant relationship between MMSE and CSF Aβ42 in ε3 homozygotes and apoE in ε4 hetero- and homozygotes respectively may suggest that both proteins may be associated independently from each other with cognitive decline.