The Incidence and Recurrence of Getting Lost in Community-Dwelling People with Alzheimer's Disease: A Two and a Half-Year Follow-Up

Ethics, design, and implementation criteria of digital assistive technologies for people with dementia from a multiple stakeholder perspective: a qualitative study

BACKGROUND

Dementia impairs the ability of people with dementia to be autonomous and independent. They need support from third parties, who should ideally respect their autonomy and independence as much as possible. Supporting people with dementia can be very burdensome for caregivers and numbers of patients increase while numbers of potential caregivers decline. Digital assistive technologies (DATs) that directly support patients or their caregivers may help bridging the increasing gap between need of support and available resources. DATs have the potential to preserve the autonomy and independence of people with dementia and promote their abilities, if they are properly designed in close interaction with future users. In our study, we focused on ethical concerns, technological requirements, and implementation criteria for DAT in general and specifically to support outdoor mobility of people with dementia.

METHODS

We applied a qualitative approach and conducted a World Café (2 tables, n = 7) and an online focus group (n = 6) with people with dementia, relatives, healthcare professionals, scientists, ethics experts, and experts for digitally-assisted medical care. We descriptively analyzed the data using a content analysis approach.

RESULTS

The participants reported technological (e.g., lack of Wi-Fi), financial (e.g., expensive devices or lack of budget for DATs), political (e.g., legal hurdles such as the European Medical Device Law or data protection regulations) as well as user-related hurdles (e.g., lack of digital competence) for the implementation of DAT in dementia care. Among the issues discussed were the importance of autonomy, independence, safety, privacy, and questions of decision making capacity in DAT's use. Participants identified opportunities and benefits in self-learning, situation-aware DATs and wished for dementia-friendly communities. They emphasized the value of personal interaction that should not be replaced, but rather supported by DAT.

CONCLUSION

The results revealed multiple hurdles and ethical concerns for DAT use and provided recommendations for designing and implementing DATs. Further investigations are needed on the impact of DAT on personal interactions in caregiving and the role of DAT in dementia-friendly communities.

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

Impaired spatial navigation is early marker of Alzheimer's disease (AD). We examined ability of self- and informant-reported navigation questionnaires to discriminate between clinically and biomarker-defined participants, and associations of questionnaires with navigation performance, regional brain atrophy, AD biomarkers, and biomarker status. 262 participants (cognitively normal, with subjective cognitive decline, amnestic mild cognitive impairment [aMCI], and mild dementia) and their informants completed three navigation questionnaires. Navigation performance, magnetic resonance imaging volume/thickness of AD-related brain regions, and AD biomarkers were measured. Informant-reported questionnaires distinguished between cognitively normal and impaired participants, and amyloid-β positive and negative aMCI. Lower scores were associated with worse navigation performance, greater atrophy in AD-related brain regions, and amyloid-β status. Self-reported questionnaire scores did not distinguish between the groups and were weakly associated with navigation performance. Other associations were not significant. Informant-reported navigation questionnaires may be a screening tool for early AD reflecting atrophy of AD-related brain regions and AD pathology.

Experiences of family caregivers taking care getting lost of persons with dementia: a qualitative study

BACKGROUND

Getting lost with family members who have dementia is a significant source of stress for family caregivers. In Taiwan, family caregivers develop strategies to deal with dementia persons who may get lost. This study aimed to explore the experiences of family caregivers caring for persons with dementia who have been lost outside the home.

METHODS

A descriptive phenomenological method was used. The COREQ checklist was used to ensure the explicit reporting of data. A total of 20 family caregivers caring for persons with dementia who were lost outside their homes were selected from hospital outpatient clinics and a day care center in northern Taiwan using purposive sampling. Data were analyzed using the Giorgi analysis method.

RESULTS

Five main themes emerged: (i) surprised persons with dementia lost outside, (ii) using strategies to prevent persons with dementia from getting lost, (iii) using strategies to find lost persons with dementia, (iv) exhaustion in long-term care persons with dementia, and (v) coping with the care load. It was found that family caregivers were surprised, nervous, and worried about persons with dementia being lost outside. They used the first strategy to supervise persons with dementia to prevent external losses. In addition, long-term supervision of persons with dementia led to mental exhaustion in the family caregivers. Finally, the family caregivers learned about loss prevention strategies and obtained family support and care replacement workers to reduce the care burden.

CONCLUSIONS

It is essential to teach family caregivers early to prevent persons with dementia from losing external strategies. Nurses also provide long-term care services to reduce the care burden on family caregivers.

Assessment tools for measurement of dementia-friendliness of a community: A scoping review

BACKGROUND

A quantitative assessment of the dementia-friendliness of a community can support planning and evaluation of dementia-friendly community (DFC) initiatives, internal review, and national/international comparisons, encouraging a more systematic and strategic approach to the advancement of DFCs. However, assessment of the dementia-friendliness of a community is not always conducted and continuous improvement and evaluation of the impact of dementia-friendly initiatives are not always undertaken. A dearth of applicable evaluation tools is one reason why there is a lack of quantitative assessments of the dementia-friendliness of communities working on DFC initiatives.

PURPOSE

A scoping review was conducted to identify and examine assessment tools that can be used to conduct quantitative assessments of the dementia-friendliness of a community.

DESIGN AND METHODS

Peer-reviewed studies related to DFCs were identified through a search of seven electronic databases (MEDLINE, CINAHL, PsycINFO, Embase, EMCare, HealthSTAR, and AgeLine). Grey literature on DFCs was identified through a search of the World Wide Web and personal communication with community leads in Australia, Canada, New Zealand, the United Kingdom, and the United States. Characteristics of identified assessment tools were tabulated, and a narrative summary of findings was developed along with a discussion of strengths and weaknesses of identified tools.

RESULTS

Forty tools that assess DFC features (built environment, dementia awareness and attitudes, and community needs) were identified. None of the identified tools were deemed comprehensive enough for the assessment of community needs of people with dementia.

Using GPS Tracking to Investigate Outdoor Navigation Patterns in Patients With Alzheimer Disease: Cross-sectional Study

BACKGROUND

Spatial disorientation is one of the earliest and most distressing symptoms seen in patients with Alzheimer disease (AD) and can lead to them getting lost in the community. Although it is a prevalent problem worldwide and is associated with various negative consequences, very little is known about the extent to which outdoor navigation patterns of patients with AD explain why spatial disorientation occurs for them even in familiar surroundings.

OBJECTIVE

This study aims to understand the outdoor navigation patterns of patients with AD in different conditions (alone vs accompanied; disoriented vs not disoriented during the study) and investigate whether patients with AD experienced spatial disorientation when navigating through environments with a high outdoor landmark density and complex road network structure (road intersection density, intersection complexity, and orientation entropy).

METHODS

We investigated the outdoor navigation patterns of community-dwelling patients with AD (n=15) and age-matched healthy controls (n=18) over a 2-week period using GPS tracking and trajectory mining analytical techniques. Here, for the patients, the occurrence of any spatial disorientation behavior during this tracking period was recorded. We also used a spatial buffer methodology to capture the outdoor landmark density and features of the road network in the environments that the participants visited during the tracking period.

RESULTS

The patients with AD had outdoor navigation patterns similar to those of the controls when they were accompanied; however, when they were alone, they had significantly fewer outings per day (total outings: P<.001; day outings: P=.003; night outings: P<.001), lower time spent moving per outing (P=.001), lower total distance covered per outing (P=.009), lower walking distance per outing (P=.02), and lower mean distance from home per outing (P=.004). Our results did not identify any mobility risk factors for spatial disorientation. We also found that the environments visited by patients who experienced disorientation versus those who maintained their orientation during the tracking period did not significantly differ in outdoor landmark density (P=.60) or road network structure (road intersection density: P=.43; intersection complexity: P=.45; orientation entropy: P=.89).

CONCLUSIONS

Our findings suggest that when alone, patients with AD restrict the spatial and temporal extent of their outdoor navigation in the community to successfully reduce their perceived risk of spatial disorientation. Implications of this work highlight the importance for future research to identify which of these individuals may be at an actual high risk for spatial disorientation as well as to explore the implementation of health care measures to help maintain a balance between patients' right to safety and autonomy when making outings alone in the community.

Associations between community participation and types of places visited among persons living with and without dementia: risks perception and socio-demographic aspects

Introduction

Increasingly, literature has focused on community participation in places visited by persons living with and without dementia. Earlier research indicates that multiple factors, including socio-demographic aspects and risk perception may influence community participation.

Aim and methods

This cross-sectional, explorative study aims to inquire into how places visited, socio-demographic aspects and risks perception are associated with self-rated community participation for persons living with and without dementia (n = 70) in Switzerland. Data was collected through face-to-face interviews with questionnaires (ACT-OUT, MoCA, sociodemographic). First, we investigated whether the number of places visited was correlated with self-rated participation; then we added socio-demographic and risks perception factors with a bivariate analysis; and searched for a model using multinomial logistic regressions.

Results

For the group of participants living with dementia, risks of falling (p = .014) and of getting lost (p = .037) were significantly associated with self-rated participation. For the group of participants living without dementia, visiting places outside the home was significantly associated with self-rated participation, especially visiting places in domain D/places for recreational and physical activities (p = .005).

Discussion and conclusions

The results of exploring multiple factors and searching for a model highlights the complexity of community participation as a construct. Risks and visiting places for recreational and physical activities seem to play a role in self-rated participation. Mobile interviews might be better suited to gain in-depth understanding on community participation for persons living with dementia.

Reduced Vision-Related Quality of Life in Dementia: A Preliminary Report

BACKGROUND

Despite experimental evidence for concurrent dementia and visual impairment, there are no currently validated vision-related quality of life measures for use in this population.

OBJECTIVE

To establish the extent to which individuals with mild to moderate dementia self-report visual impairment and determine the efficacy of established vision-related quality of life measures for use in a dementia population.

METHODS

We compared vision-related quality of life in participants with mild-moderate dementia to healthy (dementia-free) older adults using two existing questionnaire measures already validated for use in older adults. These were the Visual Activities Questionnaire (VAQ) and the 25-item National Eye Institute Visual Function Questionnaire (VFQ-25).

RESULTS

Responses on both the VAQ and VFQ-25 revealed a significant effect of dementia on self-reported vision-related quality of life. Visual impairment in dementia was identified in the domains of color discrimination, disability glare, light/dark adaption, acuity/spatial vision, depth perception, peripheral vision, visual search, and visual processing speed. Factor analysis of the data suggested that existing vision-related quality of life measures, designed for use in older adult populations, are likely to provide a robust means of assessing vision-related quality of life in older adults with dementia. This is particularly true of the VAQ, for which one latent factor emerged for both dementia and dementia-free samples.

CONCLUSION

Using existing measures designed for use in older adult populations, we have shown that people with dementia experience reduced vision-related quality of life.

Machine learning detects altered spatial navigation features in outdoor behaviour of Alzheimer's disease patients

Impairment of navigation is one of the earliest symptoms of Alzheimer's disease (AD), but to date studies have involved proxy tests of navigation rather than studies of real life behaviour. Here we use GPS tracking to measure ecological outdoor behaviour in AD. The aim was to use data-driven machine learning approaches to explore spatial metrics within real life navigational traces that discriminate AD patients from controls. 15 AD patients and 18 controls underwent tracking of their outdoor navigation over two weeks. Three kinds of spatiotemporal features of segments were extracted, characterising the mobility domain (entropy, segment similarity, distance from home), spatial shape (total turning angle, segment complexity), and temporal characteristics (stop duration). Patients significantly differed from controls on entropy (p-value 0.008), segment similarity (p-value [Formula: see text]), and distance from home (p-value [Formula: see text]). Graph-based analyses yielded preliminary data indicating that topological features assessing the connectivity of visited locations may also differentiate patients from controls. In conclusion, our results show that specific outdoor navigation features discriminate AD patients from controls, which has significant implication for future AD diagnostics, outcome measures and interventions. Furthermore, this work illustrates how wearables-based sensing of everyday behaviour may be used to deliver ecologically-valid digital biomarkers of AD pathophysiology.

Effectiveness of Interventions for Preventing People With Dementia Exiting or Getting Lost

BACKGROUND AND OBJECTIVES

People with dementia are at risk of exiting premises unsupervised, eloping, or getting lost, potentially leading to harmful or distressing consequences. This review aimed to estimate the effectiveness of interventions for preventing people with dementia from exiting or getting lost.

RESEARCH DESIGN AND METHODS

A systematic review of English sources was undertaken. Health care (EMBASE, BNI, Medline, PubMed, CINAHL, PsycINFO, AMED, HTA, CENTRAL) and gray literature (OpenGrey) databases were searched using prespecified search terms. Additional studies were identified by hand-searching bibliographies of relevant reviews and included studies. Wide inclusion criteria were set to capture a range of intervention types. Data extraction and risk of bias assessment were completed independently by two reviewers. Methods were preregistered on PROSPERO.

RESULTS

Individual and overall risk of bias was too high for statistical meta-analyses. A narrative synthesis was therefore performed. Twenty-five studies with 814 participants were included, investigating a range of nonpharmacological interventions aiming to prevent exiting, facilitate retrieval, educate participants, or a combination of these. Seventeen (68%) of the included studies had critical risks of internal bias to outcomes, providing no useful evidence for the effectiveness of their respective interventions. The remaining 8 (32%) studies had serious risks of bias. Narrative synthesis of results yielded no overall robust evidence for the effectiveness of any interventions.

DISCUSSION AND IMPLICATIONS

No evidence was found to justify the recommendation of any interventions included in this review. Future studies should focus on high-quality, controlled study designs.

Stereoscopic Depth Perception and Visuospatial Dysfunction in Alzheimer's Disease

With visuospatial dysfunction emerging as a potential marker that can detect Alzheimer's disease (AD) even in its earliest stages and with disturbance in stereopsis suspected to be the prime contributor to visuospatial deficits in AD, we assessed stereoscopic abilities of patients with AD and mild cognitive impairment (MCI). Whereas previous research assessing patients' stereoacuity has yielded mixed results, we assessed patients' capacity to process coarse disparities that can convey adequate depth information about objects in the environment. We produced two virtual cubes at two different distances from the observer by manipulating disparity type (absolute vs. relative), disparity direction (crossed vs. uncrossed) and disparity magnitude, then had participants judge the object that appeared closer to them. Two patient groups performed as well as, or even better than elderly controls, suggesting that AD patients' coarse disparity processing capacity is capable of supporting common tasks involving reaching, grasping, driving, and navigation. Results may help researchers narrow down the exact cause(s) of visuospatial deficits in AD and develop and validate measures to assess visuospatial dysfunction in clinical trials and disease diagnosis.

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

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.

Geospatial Analysis of Environmental Risk Factors for Missing Dementia Patients

BACKGROUND

Dementia-related missing incidents are highly prevalent but still poorly understood. This is particularly true for environmental/geospatial risk factors, which might contribute to these missing incidents.

OBJECTIVE

The study aimed to conduct a retrospective, observational analysis on a large sample of missing dementia patient case records provided by the police (n = 210), covering dates from January 2014 to December 2017. In particular, we wanted to explore 1) whether there were any hotspot regions of missing incidents and 2) the relationship between outdoor landmark density and missing incidents.

METHODS

Global spatial autocorrelation (Moran's I) was used to identify the potential hotspot regions for missing incidents. Meanwhile, spatial buffer and regression modelling were used to determine the relationship between outdoor landmark density and missing incidents.

RESULTS

Our demographics measures replicated and extended previous studies of dementia-related missing incidents. Meanwhile, no hotspot regions for missing incidents were identified, while higher outdoor landmark density led to increased missing incidents.

CONCLUSION

Our results highlight that missing incidents do not occur in isolated hotspots of regions but instead are endemic in patients regardless of location. Higher outdoor landmark density emerges as a significant geospatial factor for missing incidents in dementia, which crucially informs future safeguarding/intervention studies.

A Communication Infrastructure for the Health and Social Care Internet of Things: Proof-of-Concept Study

Background

Increasing life expectancy and reducing birth rates indicate that the world population is becoming older, with many challenges related to quality of life for old and fragile people, as well as their informal caregivers. In the last few years, novel information and communication technology techniques generally known as the Internet of Things (IoT) have been developed, and they are centered around the provision of computation and communication capabilities to objects. The IoT may provide older people with devices that enable their functional independence in daily life by either extending their own capacity or facilitating the efforts of their caregivers. LoRa is a proprietary wireless transmission protocol optimized for long-range, low-power, low–data-rate applications. LoRaWAN is an open stack built upon LoRa.

Objective

This paper describes an infrastructure designed and experimentally developed to support IoT deployment in a health care setup, and the management of patients with Alzheimer’s disease and dementia has been chosen for a proof-of-concept study. The peculiarity of the proposed approach is that it is based on the LoRaWAN protocol stack, which exploits unlicensed frequencies and allows for the use of very low-power radio devices, making it a rational choice for IoT communication.

Methods

A complete LoRaWAN-based infrastructure was designed, with features partly decided in agreement with caregivers, including outdoor patient tracking to control wandering; fall recognition; and capability of collecting data for further clinical studies. Further features suggested by caregivers were night motion surveillance and indoor tracking for large residential structures. Implementation involved a prototype node with tracking and fall recognition capabilities, a middle layer based on an existing network server, and a Web application for overall management of patients and caregivers. Tests were performed to investigate indoor and outdoor capabilities in a real-world setting and study the applicability of LoRaWAN in health and social care scenarios.

Results

Three experiments were carried out. One aimed to test the technical functionality of the infrastructure, another assessed indoor features, and the last assessed outdoor features. The only critical issue was fall recognition, because a slip was not always easy to recognize.

Conclusions

The project allowed the identification of some advantages and restrictions of the LoRaWAN technology when applied to the health and social care sectors. Free installation allows the development of services that reach ranges comparable to those available with cellular telephony, but without running costs like telephony fees. However, there are technological limitations, which restrict the scenarios in which LoRaWAN is applicable, although there is room for many applications. We believe that setting up low-weight infrastructure and carefully determining whether applications can be concretely implemented within LoRaWAN limits might help in optimizing community care activities while not adding much burden and cost in information technology management.

Risky wandering behaviors of persons with dementia predict family caregivers' health outcomes

OBJECTIVES

To examine the relationships between dementia persons' risky wandering behaviors and family caregivers' physical and mental health.

METHODS

A secondary analysis was conducted using the original cross-sectional data from180 dyads. The Risky Wandering and Adverse Outcome model assessed behaviors of eloping and getting lost outside the house for dementia persons. Data were analyzed using descriptive statistics, Pearson's correlation coefficient and hierarchical regressions.

RESULTS

The mean age of caregivers was 56.01 years (SD = 13.8); 65% were female. Younger caregivers experienced greater physical fatigue and sleep disturbance. Presence of foreign helpers predicted a reduction in mental and physical fatigue of caregiver (β = -0.186, p < .05; β = 0.198, p < .05, respectively). Getting lost outside of the house influenced caregivers' mental fatigue (β = 0-0.215, p < .05); eloping behavior influenced caregivers' sleep disturbance (β = 0.231, p < .05). Care-receivers' activities of daily living affected caregivers' depressive symptoms (β = -0.179, p < .05).

CONCLUSIONS

Dementia family caregiver physical and mental health problems have distinct predictors. Employing the Risky Wandering and Adverse Outcome model could inform policy makers regarding long-term care resources to improve dementia care.

Spatial reorientation decline in aging: the combination of geometry and landmarks

OBJECTIVES

The study is focused on the assessment of reorientation skills in a sample of community-dwelling elderly people, manipulating landmarks and geometric (layout) information.

METHOD

A neuropsychological assessment was administered to 286 elderly participants, divided into six groups (healthy controls, HC; four subgroups of participants with mild cognitive impairment, MCI; participants with probable dementia, Prob_D) and tested with the Virtual Reorientation Test (VReoT). VReoT manipulated different spatial cues: geometry and landmarks (proximal and distal).

RESULT

Compared with HC, participants with MCI and Prob_D showed to be impaired in tasks involving geometry, landmarks and a combination of them. Both single and multiple domain impairment in MCI had an impact on reorientation performance. Moreover, VReoT was marginally able to discriminate between amnesic and non-amnesic MCI. The occurrence of getting lost events seemed to be associated to learning of geometric information.

CONCLUSION

The associative strength between landmark and target plays an important role in affecting spatial orientation performance of cognitively impaired participants. Geometry significantly supports landmark information and becomes helpful with the increase of cognitive impairment which is linked to a decrement in landmark encoding. VReoT seems to represent a reliable evaluation supplement for spatial orientation deficits in prodromal stages of dementia.

Prevalence and Risk Factors for Depression among Caregivers of Alzheimer's Disease Patients in Saudi Arabia

Objectives

To identify prevalence and risk factors of depression among caregivers of Alzheimer' disease (AD) patients.

Methods

In a cross-sectional study, 110 caregivers of AD patients participated in this study (51 males and 59 females). Patients data were obtained from patients' records at Aseer Central Hospital. Depression among caregivers was assessed by using the Hamilton Rating Scale for Depression.

Results

The age of caregivers ranged from 17 to 85 years (Mean±SD: 41.1±14.0 years). Prevalence of depression among caregivers was 70%. Caregivers were mainly sons/daughters (69.1%) or spouses (11.8%). A total of 33 caregivers (30%) had mild depression while 44 (40%) had moderate depression. Prevalence of depression was significantly higher among caregivers of AD patients who were exposed to repeated falling down (p=0.003), but did not differ significantly among caregivers who were exposed to repeated pneumonia or getting lost. Caregivers' scores of depression positively correlated with duration of caregivers' daily stay with AD patients (r=0.272, p=0.004), but did not correlate significantly with either caregivers' age or patients' age. Moreover, caregivers' depression did not differ significantly according to their marital status, educational status, employment status, or monthly income.

Conclusions

Prevalence of depression among AD caregiver is high. Risk factors for depression include patients' exposure to repeated falls and prolonged stay with patients. Therefore, psychiatric care should be provided to caregivers, home safety should be maintained to avoid falls, and several persons should interchangeably provide care to AD patients.

Assessing wandering risk among individuals with Alzheimer's disease and dementia: a pilot study

BACKGROUND

We examined a screening instrument to assess risk for wandering among individuals with Alzheimer's disease and dementia according to caregiver informants.

METHODS

Pilot data were collected on the Risk of Wandering (RoW) screening instrument by 48 responses from an online survey using the Alzheimer's Association Trial Match system.

RESULTS

Results indicated acceptable evidence of the internal consistency of scores for the data obtained, α = 0.81. Receiver operating characteristic curve results indicated acceptable evidence of the screening instrument scores' ability to discriminate between individuals who eloped and those who did not wander off, AUC = 0.72, P = 0.003.

CONCLUSIONS

A cut-off score for future use is suggested along with directions for future research. The development of a screening instrument would appear to be preferable to restricting the movement of these individuals or unnecessarily invading their privacy through monitoring devices while simultaneously balancing the desire to prevent distress, serious injury, or death.

Getting Lost Behavior in Patients with Mild Alzheimer's Disease: A Cognitive and Anatomical Model

Background

Getting lost behavior (GLB) in the elderly is believed to involve poor top-down modulation of visuospatial processing, by impaired executive functions. However, since healthy elderly and elderly with Alzheimer's disease (AD) experience a different pattern of cognitive decline, it remains unclear whether this hypothesis can explain GLB in dementia.

Objective

We sought to identify whether poor executive functions and working memory modulate the relationship between visuospatial processing and prevalence of GLB in healthy elderly and patients with AD. Complementary to this, we explored whether brain regions critical for executive functions modulate the relationship between GLB and brain regions critical for visuospatial processing.

Method

Ninety-two participants with mild AD and 46 healthy age-matched controls underwent neuropsychological assessment and a structural MRI. GLB was assessed using a semistructured clinical interview. Path analysis was used to explore interactions between visuospatial deficits, executive dysfunction/working memory, and prevalence of GLB, in AD and controls independently.

Results

For both healthy controls and patients with mild AD, visuospatial processing deficits were associated with GLB only in the presence of poor working memory. Anatomically, GLB was associated with medial temporal atrophy in patients with mild AD, which was not strengthened by low frontal gray matter (GM) volume as predicted. Instead, medial temporal atrophy was more strongly related to GLB in patients with high frontal GM volumes. For controls, GLB was not associated with occipital, parietal, medial temporal, or frontal GM volume.

Conclusion

Cognitively, a top-down modulation deficit may drive GLB in both healthy elderly and patients with mild AD. This modulation effect may be localized in the medial temporal lobe for patients with mild AD. Thus, anatomical substrates of GLB in mild AD may not follow the typical top-down modulation mechanisms often reported in the healthy aging population. Implications advance therapeutic practices by highlighting the need to target both working memory and visuospatial deficits simultaneously, and that anatomical substrates of GLB may be disease specific.