APOE and spatial navigation in amnestic MCI: Results from a computer-based test.

Abstract

OBJECTIVE: We investigated the association between APOE ε4 status and spatial navigation in patients with amnestic mild cognitive impairment (aMCI) and assessed the role of hippocampal volume in this association. METHOD: Participants were 74 patients with clinically confirmed aMCI (33 APOE ε4 noncarriers, 26 heterozygous, and 15 homozygous ε4 carriers). Body-centered (egocentric) and world-centered (allocentric) spatial navigation in a computerized human analogue of the Morris Water Maze was assessed. Brain MRI with subsequent automated hippocampal volumetry was included. RESULTS: Groups were similar in neuropsychological profile. Controlling for age, sex, education, and free memory recall, the APOE ε4 carriers performed more poorly on all spatial navigation subtasks (ps < .05). APOE ε4 homozygotes performed worse than heterozygotes (p = .021). Right hippocampal volume accounted for the differences in allocentric and delayed subtasks (ps > .05), but not in the egocentric subtask (p < .001). CONCLUSIONS: Using an easy-to-use, computer-based tool to assess spatial navigation, we found spatial navigation deficits to worsen in a dose-dependent manner as a function of APOE ε4 status. This was at least partially due to differences in right hippocampal volume.

Presence of lacunar infarctions is associated with the spatial navigation impairment in patients with mild cognitive impairment: a DTI study

“…Further prospective longitudinal studies with age-matched healthy controls and standardized neuropsychological scales that are specific for mild cognitive impairment in patient with lacunar infarction would be necessary for us to better evaluate the timing of neuroanatomical changes relative to cognitive impairments and to validate whether the acknowledged biomarkers which could be used for early detection [11]. Second, the computerized test based on the MWM paradigm may be a useful tool for evaluation of spatial navigation deficits [8]. However, it should be noted that the real-space and computerized 2-dimensional versions are not fully interchangeable, as the computerized spatial navigation tasks lack vestibular and proprioceptive feedback that is normally available in the real-world navigation tasks and that contributes to successful navigation [9].…”

“…Spatial navigation was tested by PC tests Amunet (NeuroScios GmbH, Austria) which are human analogue of the Morris Water Maze (MWM) task. Studies with the same paradigm, but using different software were published previously [6, 8, 37]. The Amunet tests are designed to separate two different strategies of spatial navigation, egocentric that relies on individual's position and allocentric strategy centered on the object rather than on the observer [22].…”

“…The last “delayed” subtest involved the same design, as the “allocentric” subtest but is administered 30min after the end of the allocentric subtest. Each subtest consisted of eight trials, except of delayed subtest which consisted of only two trials [8]. The index was averaged across all eight trials from each of the subtest.…”

“…The index was averaged across all eight trials from each of the subtest. The distance between the subjects' choice and the correct goal location measured in pixels was used in the analysis as a main index (average total error) for measuring of spatial navigational ability [8]. Other indexes, such as the time, which the subjects cost in each trial, the total time which the subjects cost in each subtest (average duration), path difference (average distance deviation), and angular difference (average angular deviation), were also measured.…”

“…We can distinguish egocentric (route or body centered) and allocentric (world centered) spatial navigation strategy [6, 7]. Egocentric navigation is body centered and localized mostly in parietal cortex and striatum, while the allocentric navigation is world centered and it is dependent mostly on the hippocampus [6, 7] Impaired spatial navigation is a frequently reported symptom of MCI and Alzheimer's disease (AD) patients in both real-space and virtual environments, with similar results [8]. For example, Czech study [9] used a human analog of the Morris Water Maze (hMWM) to demonstrate a spatial navigation impairment in patients with multiple-domain amnestic mild cognitive impairment (aMCI) of a similar magnitude to that found in AD patients.…”