Have I Been Here? Sense of Location in People With Alzheimer's Disease

Abstract

Background: When navigating in a particular space, a sense of being at a current location is of great help for the navigators in reaching their destination or getting back to the start. To accomplish this work, interwoven neural structures and neurons are called into play. This system is called the heading direction cell-place cell-grid cell circuit. Evidence from various neuroscience studies has revealed that the regions responsible for this circuit are damaged in the early stages of Alzheimer's disease (AD). This may explain why wayfinding difficulty is one of the most frequent symptoms in persons with AD. The aim of this study was to examine the sense of location (SoL) in persons with mild AD, persons with prodromal AD (prAD), and those who were cognitively unimpaired (CU).Methods: We invited people with mild AD, prAD, and CU to participate in this study. The venue of the core experiment to assess SoL was a 660-m path located on the university campus. The participants were instructed to take a walk on the path and press a device to indicate their arrival at each of the five carefully chosen targets. The linear deviations from the target site were compared among the groups.Results: A total of 20 AD, 28 prAD, and 29 CU persons completed the study. Their Mini-Mental State Examination scores were on average 20 (SD 3), 24 (SD 3), and 28 (SD 2). The groups were well differentiated regarding several measurements for cognitive ability and spatial navigation. As for the SoL, the hit rates of exact location with linear deviation of 16 m or less were 0.05, 0.54, and 0.86 for AD, prAD, and CU persons, respectively. The hit rates were well correlated with the presence of getting lost. Also, SoL differentiated well among CU, PrAD, and AD in terms of average linear deviation.Conclusions: Our employing linear deviation by utilizing a grid-cell function device as an assessment for SoL showed distinct features among the three groups. This model can be used to develop more delicate devices or instruments to detect, monitor, and aid spatial navigation in persons with prAD and AD.

Short Digital Spatial Memory Test Detects Impairment in Alzheimer’s Disease and Mild Cognitive Impairment

“…Indeed, previous studies have shown severe impairments in scene recognition, remembering turns at decision points and recalling the temporal order of routes in both patients with AD dementia and MCI. Furthermore, some of these studies have found that route continuation and route ordering are impaired in both patients with AD dementia and MCI, to the same extent [11,14,24,27,29,33,42,61,77].…”

“…However, these small-scale spatial tests are highly inflexible, measure only a single aspect in the spatial memory spectrum or have proven to be poor predictors of navigational abilities [21] and cognitive decline [22]. Other studies have aimed to simulate the complexity of real-life situations by assessing large-scale spatial navigation in real-world scenarios such as hospital settings (for example, [11,14,[23][24][25][26][27][28]) or with innovative tests incorporating advanced virtual reality (VR) paradigms such as the Memory Island Test and the Sea Hero Quest [14,25,26,[29][30][31][32][33][34][35][36][37][38]. Multiple studies have proven that real-world scenarios and VR applications appear to be more sensitive in identifying spatial navigation deficits in patients with AD in both the prodromal and symptomatic stage [11,14,25,26,[39][40][41][42].…”

Time Perception in Prodromal Alzheimer's Dementia and in Prodromal Dementia With Lewy Bodies

“…The inclusion criteria for a diagnosis of prAD were as follows: (1) SPECT showed decreased perfusion in parietal association area, posterior cingulate, precuneus; (2) magnetic resonance imaging (MRI) showed atrophy, especially in the medial temporal lobe and/or posterior cortical regions; (3) objective evidence of impairment in one or more cognitive domains, including memory, attention, language, visuospatial skills, or executive function; (4) independent activities of daily living; (5) other conditions that may cause cognitive impairment must be ruled out (17)(18)(19). The inclusion criteria for the diagnosis of prDLB were as follows: (1) more than one core symptoms of DLB, such as fluctuating cognition, visual hallucinations, rapid eye movement sleep behavior disorder (RBD), and more than one symptom of Parkinson's disease; (2) using TRODAT to confirm the reduced uptake of dopamine transporter in striatum; (3) independent activities of daily living; (4) other conditions that may cause cognitive impairment must be ruled out (20,21).…”

Spatial navigation questionnaires as a supportive diagnostic tool in early Alzheimer’s disease

“… 33 , 36 A recent study also showed that self-reported spatial navigation abilities may not predict objectively measured sense of location in the real world in individuals with aMCI and mild AD dementia. 37 In addition, the extent of life-space mobility (i.e., the measure of movement extending from within one’s own home to movement beyond one’s own town or geographic region 38 may interfere with reported spatial navigation abilities, as more frequent travel to more remote locations is more challenging. 38 , 39 Although previous studies have suggested potential benefits and limitations of reported spatial navigation abilities in screening for AD, comparisons between self- and informant-reported spatial navigation questionnaires, and their associations with brain atrophy and biomarkers across the AD continuum have not been researched.…”