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

UNLABELLED 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.