ABSTRACT
BACKGROUND: Spatial navigation deficits are reported as early symptoms of Alzheimer's disease (AD) alongside episodic memory ones. The aim of the present study was to ascertain whether neuropsychological deficits of visuospatial long-term memory can predict behavioral alterations during the navigation of older adults in novel urban environments along the normal aging-dementia continuum of the Alzheimer's type. METHODS: A total of 24 community-dwelling patients with Mild Cognitive Impairment (MCI) due to AD, 27 individuals with subjective cognitive decline (SCD), and 21 healthy controls were assessed in terms of their sequential egocentric and allocentric navigation abilities by using a modified version of the Detour Navigation Test, and neuropsychologically tested by the Corsi learning suvra-span (CLSS) test. Generalized linear models were adopted to verify whether the scores obtained by the three groups in the CLSS test predicted wrong turns and moments of hesitation during the navigation task, with the results presented as topographical disorientation scores. RESULTS: Higher scores in the CLSS test predicted fewer wrong turns (b = -0.05; z = -2.91; p = 0.004; net of between-groups differences) and moments of hesitation for patients with MCI due to AD (b = -0.14; z = -2.43; p = 0.015), and individuals with SCD (b = -0.17; z = -3.85; p < 0.001). CONCLUSIONS: Since the CLSS test has been reported to be a reliable measure of ecological navigational abilities in the progression towards AD dementia, we recommend its use in clinical practice and highlight implications for future research.
ABSTRACT
(1) Background: Spatial cognition (SC) is one of the earliest cognitive domains to be impaired in the course of Alzheimer's disease (AD), resulting in spatial disorientation and becoming lost even in familiar surroundings as later dementia symptoms. To date, few studies have identified initial alterations of spatial navigation (SN) in the premorbid AD phase by real-world paradigms, and none have adopted an innovative technological apparatus to better detect gait alterations as well as physiological aspects correlated to spatial disorientation (SD). The present study aimed at exploring initial SN defects in patients with prodromal AD via a naturalistic task by using a sensory garment. (2) Methods: 20 community-dwelling patients with Mild Cognitive Impairment (MCI) due to AD and 20 age/education controls were assessed on their sequential egocentric and allocentric navigation abilities by using a modified version of the Detour Navigation Test (DNT-mv). (3) Results: When compared to controls, patients with MCI due to AD exhibited higher wrong turns (WT) and moments of hesitation (MsH) in the DNT-mv, reflecting difficulties both in sequential egocentric and allocentric navigation, depending on hippocampal deterioration. Moreover, they reported more complaints about their SN competencies and lower long-term visuospatial memory abilities than controls. Remarkably, WTs and MsH manifested in the allocentric naturalistic task of the DNT-mv were associated with autonomic nervous system alteration pertaining to cardiac functioning in the whole sample. (4) Conclusions: Naturalistic navigation tests of hippocampal function using a continuous non-invasive monitoring device can provide early markers of spatial disorientation in patients with MCI due to AD. Future studies should develop cognitive remediation techniques able to enhance SC residual abilities in patients at high risk of conversion into dementia and ecological paradigms to be replicated on a large scale.
ABSTRACT
Parkinson's Disease's (PD) neuropsychological profile is often characterized by altered performance in executive functions (EF) tasks, with a remarkable impact on patients' quality of life. To date, the available neuroimaging literature lacks conclusive evidence about neural patterns underlying EF deficits in PD. Here, we aimed to synthesize the results of PET/fMRI studies examining the differences in brain activation between PD patients and controls during EF tasks, focusing on the three main EF sub-components: cognitive flexibility, working memory, and response inhibition. We conducted a coordinate-based meta-analysis to assess the converging alterations in brain activity in PD patients compared to controls. We assessed the association between aberrant patterns of activity and the EF sub-domains. We found a significant association between hypoactivation patterns in PD converging at the level of the right inferior frontal gyrus in response inhibition tasks, whereas hypoactivation in the left inferior frontal gyrus was found in association with the cognitive flexibility domain. Our results confirm the existence of neural alterations in PD patients in relation to specific EF sub-domains.
