Episodic memory and speed/attention deficits are associated with Alzheimer-typical CSF abnormalities in MCI

Abstract

Mild cognitive impairment (MCI) is regarded as the prodromal stage of dementia disorders, such as Alzheimer's disease (AD).

Objective: To compare the neuropsychological profiles of MCI subjects with normal concentrations of total tau (T-tau) and Abeta42 in CSF (MCI-norm) to MCI subjects with deviating concentrations of the biomarkers (MCI-dev). MCI-norm (N = 73) and MCI-dev (N = 73) subjects were compared to normal controls (N = 50) on tests of speed/attention, memory, visuospatial function, language and executive function.

Results: MCI-norm performed overall better than MCI-dev, specifically on tests of speed and attention and episodic memory. When MCI-dev subjects were subclassified into those with only high T-tau (MCI-tau), only low Abeta42 (MCI-Abeta) and both high T-tau and low Abeta42 (MCI-tauAbeta), MCI-tauAbeta tended to perform slightly worse. MCI-tau and MCI-Abeta performed quite similarly.

Conclusions: Considering the neuropsychological differences, many MCI-norm probably had more benign forms of MCI, or early non-AD forms of neurodegenerative disorders. Although most MCI-dev performed clearly worse than MCI-norm on the neuropsychological battery, some did not show any deficits when compared to age norms. A combination of CSF analyses and neuropsychology could be a step toward a more exact diagnosis of MCI as prodromal AD.