title: Spatial navigation testing discriminates two types of amnestic mild cognitive impairment.
abstract: The hippocampus is essential for consolidation of declarative information and spatial navigation. Alzheimer's disease (AD) diagnosis tends to be preceded by a long prodromal period and mild cognitive impairment (MCI). Our goal was to test whether amnestic MCI comprises two different subgroups, with hippocampal and non-hippocampal memory impairment, that vary with respect to spatial navigation ability. A total of 52 patients were classified into two subgroups: non-amnestic MCI (naMCI) (n=10) and amnestic MCI (aMCI) (n=42). The aMCI subgroup was further stratified into memory impairment of hippocampal type-hippocampal aMCI (HaMCI) (n=10) (potential preclinical AD) and isolated retrieval impairment-non-hippocampal (NHaMCI) (n=32). Results were compared to control (n=28) and AD (n=21) groups. We used the Hidden Goal Task, a human analogue of the Morris Water Maze, to examine spatial navigation either dependent (egocentric) or independent of individual's position (allocentric). Overall, the HaMCI group performed poorer on spatial navigation than the NHaMCI group, especially in the latter trials when the HaMCI group exhibited limited capacity to learn and the NHaMCI group exhibited a learning effect. Finally, the HaMCI group performed almost identically as the AD group. Spatial navigation deficit is particularly pronounced in individuals with hippocampus-related memory impairment and may signal preclinical AD.
authors.affiliation: Memory Disorders Clinic, Department of Neurology, 2nd Medical School, Charles University in Prague, Prague, Czech Republic. JanLaczo@seznam.cz
authors.forename: Jan
authors.initials: J
authors.lastname: Laczó
authors.forename: Kamil
authors.initials: K
authors.lastname: Vlcek
authors.forename: Martin
authors.initials: M
authors.lastname: Vyhnálek
authors.forename: Olga
authors.initials: O
authors.lastname: Vajnerová
authors.forename: Michael
authors.initials: M
authors.lastname: Ort
authors.forename: Iva
authors.initials: I
authors.lastname: Holmerová
authors.forename: Martin
authors.initials: M
authors.lastname: Tolar
authors.forename: Ross
authors.initials: R
authors.lastname: Andel
authors.forename: Martin
authors.initials: M
authors.lastname: Bojar
authors.forename: Jakub
authors.initials: J
authors.lastname: Hort
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000647:Amnesia / Q000150:complications* / Q000175:diagnosis*; D000704:Analysis of Variance; D003071:Cognition / Q000502:physiology; D003072:Cognition Disorders / Q000150:complications* / Q000175:diagnosis*; D005260:Female; D006624:Hippocampus / Q000503:physiopathology*; D006801:Humans; D007858:Learning / Q000502:physiology; D008297:Male; D008568:Memory / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D009949:Orientation / Q000502:physiology; D013028:Space Perception / Q000502:physiology*