Episodic memory and speed0attention deficits are associated with Alzheimer-typical CSF abnormalities in MCI

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-t) and Ab42 in CSF (MCI-norm) to MCI subjects with deviating concentrations of the biomarkers (MCI-dev). MCI-norm (N 5 73) and MCI-dev (N 5 73) subjects were compared to normal controls (N 5 50) on tests of speed0attention, 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 Ab42 (MCI-Ab) and both high T-tau and low Ab42 (MCI-tauAb), MCI-tauAb tended to perform slightly worse. MCI-tau and MCI-Ab 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. (JINS, 2008, 14, 582–590.)