Development of a Questionnaire on Everyday Navigational Ability to Assess Topographical Disorientation in Alzheimer’s Disease

Abstract

We developed a Questionnaire on Everyday Navigational Ability (QuENA) to detect topographical disorientation (TD) in patients with Alzheimer’s disease (PwAD). In the QuENA, 3 items were designed to assess landmark agnosia, 2 for egocentric disorientation, 3 for heading disorientation, and 2 for inattention. The PwAD and their caregivers rated QuENA according to which TD symptoms would occur. Regarding the construct validity, confirmatory factor analysis showed that the caregiver version of the QuENA fits the proposed TD model well but the patient version does not. Regarding the internal consistency, the Cronbach’s α for the caregiver version was 0.91 and that for the patient version was 0.87. A discrepancy existed between the appraisal of navigational abilities by PwAD and by caregivers, and it was correlated with the number of getting lost (GL) events. The caregiver version of QuENA is a feasible, reliable, and valid instrument to assess TD and it also discriminates well between the PwAD with GL and those without.

Keywords

Alzheimer’s disease topographical disorientation questionnaire reliability validity dementia

Introduction

Topographical disorientation (TD) refers to a syndrome in which the spatial navigational ability of an individual is selectively impaired in real-world environments, usually caused by a variety of brain disorders, such as dementia, traumatic brain injuries, stroke, epilepsy, and developmental disorders.^1,2 The manifestations of TD, however, are heterogeneous and multifaceted. Aguirre and D'Esposito² created a taxonomy that reflects various behavioral impairments for TD and linked each of them to neuroanatomical damage. Landmark agnosia, egocentric disorientation (ED), heading disorientation (HD), and anterograde disorientation are the 4 types and the corresponding cerebral area of damage are the lingual gyrus, posterior parietal cortex, retrosplenial cortex, and parahippocampus, respectively. People with landmark agnosia are unable to recognize familiar landscapes or buildings; patients with ED are unable to represent the environment from a first-person perspective and those with HD fail in deriving directional information from successfully recognized landmarks. Many researchers believe that TD occurs not only after an impaired spatial representation but also because of an executive dysfunction.^3
–5 Getting lost (GL), as a behavioral consequence to TD, occurs when patients with TD actually experience an inability to reach a familiar place or return home without an escort or aid from others.⁶ People with a particular type of TD usually adopt compensatory skills to navigate in their familiar environments, such as landmark scanning, sequencing landmarks, or body position,⁷ and tend to get lost when these compensatory cognitive resources are inadequate.

Spatial navigational ability is vulnerable in patients with Alzheimer’s disease (PwAD) and this deserves our attention. The prevalence of TD among community dwelling PwAD, for example, is 40% to 54%,^8,9 but the pathophysiology of TD remains unclear. Before a GL event, PwAD are prone to make incorrect turns while driving, failing to identify familiar landmarks or scenes, or failing to access their stored allocentric spatial memory.^10–14 Repetitive occurrences of GL events in a patient will result in restraint or premature institutionalization.⁸ Thus, it is important to detect and to describe the nature of TD in PwAD.

Evidence has shown that the neurodegenerative pattern of Alzheimer’s disease (AD) is heterogeneous and a classification of AD to subtypes has been suggested.^15

–18 Regarding the spatial navigational ability, developing a feasible and reliable questionnaire with ecological validity is essential.^19,20 Previous questionnaires for spatial navigational ability mostly focused on strategies or habits^21
–23 and evaluated how good the ability was rather than uncover deficits. The Wayfinding Effectiveness Scale, developed by Algase and colleagues,²¹ assesses way-finding efficiency across different types of goals and strategies. Another example is Lawton’s Wayfinding Strategy Scale that focuses on the strategies and the habits adopted by people performing way-finding behavior.^22,23 Strategies and habits indeed play a role in successful way-finding but cannot reflect the nature of way-finding deficits. Although Skelton et al²⁴ developed a scale for GL behaviors, it is used to describe the situations and the frequency of GL.

In an attempt to meet the clinical needs of assessing TD symptoms occurring in PwAD, we developed a structured interview to assess the severity of TD and to reveal the possible underlying mechanisms of GL behaviors so that health care providers may provide more comprehensive evaluation and care for these patients. Its reliability and validity were also tested. We were especially concerned with the context of their familiar environments because as their cognitive abilities deteriorate, PwAD will gradually restrict themselves to a narrower range. If PwAD cannot find their way in familiar environments, the danger is obvious.^6,9

Methods

Participants

We invited 218 community-dwelling PwAD and their caregivers to join the study. All the patients regularly visited Alzheimer Disease Center of a national university and had no ambulatory problems, aphasia, focal cerebral damage, or visual or auditory impairments. Moreover, they must have been living in their current residence before the development of AD. The caregivers had been living with their patient and had adequate observation of the patient’s daily life. The PwAD were diagnosed by a senior behavioral neurologist according to the criteria of the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA)²⁵ and of the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition)²⁶ and underwent neuropsychological assessments including the Cognitive Abilities Screening Instrument (CASI)²⁷ and the Mini-Mental State Examination (MMSE).²⁸ The study was approved by the Institutional Review Board for the Protection of Human Subjects. Participant in the study was voluntary and an informed consent was given before the interview.

Construction of the QuENA

Because of the complexity and the heterogeneity of TD, we adopted a hybrid model to describe the manifestation of TD in the PwAD and used it as the construct of the Questionnaire on Everyday Navigational Ability (QuENA). The hybrid model was derived from Aguirre’s taxonomy of the TD and the studies examined TD in the PwAD.^2,5,9 The QuENA consists of 10 items, each of which defines a TD symptom.^1,2,5,29,30 The participants were asked to rate a 4-point scale where a specific symptom would occur (0 = never; 1 = in a less familiar place; 2 = in a moderately familiar place; 3 = in a very familiar place). The familiarity was defined according to how frequently an individual would visit a place and the geographical distance from home, as shown in the questionnaire (Appendix). A higher score indicates a severe condition. The 10 items were categorized into 4 subscales, namely landmark and scene agnosia (LSA) in 3, ED in 2, HD in 3, and inattention (INA) in 2. In addition to the TD symptoms, we also collected information about GL events of the patients from the patients as well as their caregivers. Only GL events that occurred in the familiar environments of the patients and after the onset of AD were taken into consideration.

Two versions of the QuENA were designed, that is, patient version (P-version) and caregiver version (C-version), which were identical in their construct and the description. The P-version requested PwAD to evaluate themselves on TD symptoms, while the C-version was a report from the caregivers about their patient’s TD manifestation. The P- and C-versions were administrated separately by a single interviewer.

Reliability

The reliability of the QuENA was established by internal consistency (Cronbach’s α) and test–retest reliability (Pearson’s r). Cronbach’s α was administrated in the 4 subscales and the full scale. The P- and C-versions were readministrated to 20 pairs of participants 4 weeks after the initial interview.

Validity

Based on GL being one of the most serious outcomes of TD, the validity of the QuENA was evaluated by construct validity and diagnostic accuracy for GL. The construct validity was derived from confirmatory factor analysis (CFA). Because χ² is sensitive to sample size, the overall model fitting was evaluated by the goodness-of-fit index (GFI), comparative fit index (CFI), Tucker-Lewis index (TLI), and root mean square error of approximation (RMSEA). The acceptability of the model fit was judged by the recommended standards: GFI, CFI, and TLI > 0.90, as well as RMSEA values of 0.08 or less for a close-fit.³¹

As mentioned previously, the QuENA was aimed at identifying the risk of GL in PwAD, and its diagnostic accuracy was measured by the area under the receiver operator characteristic (ROC) curves (area under the curve [AUC]), which tests whether the QuENA can discriminate the patients who had experienced GL from those who had not. The cutoff point was determined by the Youden index or J, which is defined as the maximum vertical distance between the ROC curve and the diagonal or chance line, hence J = maximum (sensitivity + specificity − 1).^32,33

Analysis

We used t test to compare demographic data and the factors of interest between the PwAD with GL and those without and those between different versions of the QuENA. The reliability was estimated by internal consistency (Cronbach’s α) and the test–retest reliability (Pearson’s r). The construct validity was established by CFA. The diagnostic validity of the QuENA was determined by the ROC curves. All the analyses were carried out using SPSS 15.0 and AMOS 7.0 software.^34,35

Results

The Participants

A total of 218 PwAD (144 females) and 218 caregivers completed the study. The mean age of the patients was 75.3 years (standard deviation [SD] = 9.4 years), formal education was 5.6 years (SD = 4.9 years), onset age was 72.1 years (SD = 10.2 years), and the duration of dementia was 3.2 years (SD = 3.6 years). The number of years at current residence of the patients was 29.4 years (SD = 21.8 years).

The QuENA

No difference was detected in the demographic data, the related variables, or neuropychological tests between the patients with GL (GL group) and those without (non-GL group; Table 1). However, differences existed in the QuENA between the GL and non-GL groups in both P- and C-versions (Table 2). Regarding the appraisal of each symptom of the QuENA, the discrepancy between the caregivers and the patients was obvious (Table 3). Moreover, 106 (48.6%) patients had been lost before. Previous studies adopted the discrepancy between the assessment from caregiver and that from patient as the index of the patient’s self-awareness toward a specific cognitive deficit.^36
–38 We adopted the discrepancy approach to assess the awareness of TD in AD patients and compared the discrepancy score across 3 GL frequencies (never = 112 patients, single = 71 patients, and multiple = 35 patients), the results are shown below. As seen in Figure 1, a difference existed among the 3 groups (F = 23.1, degrees of freedom = 2, P < .001) and the post hoc comparison (Scheffe’s correction) showed that the discrepancy score in the multiple GL group was significantly higher than the other 2 groups. The awareness of TD in those who experienced multiple GL events was the worst.

Figure 1.

Discrepant scores, as patient’s total score subtracted from caregiver’s scores, across 3 groups with different experience in getting lost. *P < .001.

Table 1.

Characteristics and Navigational Abilities of the Patients Based on the Incidence of GL or Not

Group (number)	GL (106)	No GL (112)	P values
Demographic data
Male, n (%)	36 (34)	38 (34)	NS
Age, years, mean (SD)	74.7 (9.4)	75.7 (9.5)	NS
Education, years, mean (SD)	6.1 (4.8)	5.2 (5.1)	NS
Residential, years, mean (SD)	25.6 (21.4)	30.1 (22.2)	NS
Days out per week, before AD	5.9 (2.1)	5.6 (2.4)	NS
Days out per week, after AD	2.5 (3.0)	4.1 (3.2)	.000
Alzheimer’s disease
Onset age, years, mean (SD)	71.8 (9.7)	72.3 (10.6)	NS
Duration, years, mean (SD)	2.9 (2.5)	3.4 (4.4)	NS
MMSE, mean (SD)	17.5 (6.2)	17.2 (5.1)	NS
CASI, mean (SD)	59.8 (19.2)	59.7 (18.4)	NS
QuENA-C
LSA, mean (SD)	3.5 (2.7)	1.6 (1.8)	.000
ED, mean (SD)	2.7 (1.9)	1.0 (1.3)	.000
HD, mean (SD)	3.3 (2.9)	1.2 (1.8)	.000
INA, mean (SD)	2.4 (2.1)	0.7 (1.1)	.000
Full scale, mean (SD)	12.0 (7.8)	4.4 (4.9)	.000
QuENA-P
LSA, mean (SD)	2.0 (2.4)	0.7 (1.3)	.000
ED, mean (SD)	1.3 (1.7)	0.4 (0.9)	.000
HD, mean (SD)	1.4 (2.0)	0.7 (1.5)	.005
INA, mean (SD)	1.3 (1.8)	0.4 (0.8)	.000
Full scale, mean (SD)	6.0 (6.1)	2.1 (3.5)	.000

Abbreviations: GL, getting lost; QuENA, Questionnaire on Everyday Navigational Ability; P, patient; C, caregiver; MMSE, Mini-Mental State Examination; CASI, Cognitive Abilities Screening Instrument; LSA, landmark and scene agnosia; ED, egocentric disorientation; HD, heading disorientation; INA, inattention; SD: standard deviation; AD: Alzheimer’s disease.

Table 2.

The Results of CASI Subitems Between GL and Non-GL Groups

Subitems (full score)	GL, n = 106	Non-GL, n = 112	P values
Remote memory (10)	8.3 (2.1)	8.3 (2.3)	.888
Recent memory (12)	4.3 (3.5)	4.0 (3.2)	.528
Attention (8)	6.6 (1.6)	6.7 (1.1)	.567
Mental manipulation (10)	5.5 (3.0)	5.5 (3.3)	.915
Orientation (18)	9.7 (5.5)	9.9 (5.3)	.764
Abstract thinking (12)	5.7 (1.9)	5.8 (1.9)	.840
Language (10)	7.8 (1.9)	7.9 (1.8)	.956
Drawing (10)	7.3 (3.0)	6.8 (3.2)	.256
Verbal fluency (10)	4.7 (2.5)	4.7 (2.3)	.835

Abbreviations: CASI, Cognitive Abilities Screening Instrument; GL, getting lost.

Table 3.

The Discrepancy Between Patients and Caregivers

	QuENA-C	QuENA-P	P values
Full scale	8.1 (7.5)	4.0 (5.2)	.0000
Landmark and scene agnosia	2.6 (2.5)	1.3 (2.0)	.0000
Egocentric disorientation	1.8 (1.8)	0.8 (1.4)	.0000
Heading disorientation	2.3 (2.6)	1.1 (1.8)	.0000
Inattention	1.5 (1.9)	0.9 (1.4)	.0000

Abbreviation: QuENA, Questionnaire on Everyday Navigational Ability; P, patient; C, caregiver.

Reliability

Cronbach’s α coefficient for P-version full scale was 0.876, LSA-P was 0.823, ED-P was 0.777, HD-P was 0.799, and INA-P was 0.674. Similarly, the coefficient for the C-version full scale was 0.913, LSA-C was 0.836, ED-C was 0.745, HD-C was 0.843, and INA-C was 0.775. The test–retest reliability (Pearson's r) of the P-version was 0.780 (P < .001) and C-version was 0.902 (P < .001).

Validity

The GFI, CFI, TLI, and RMSEA of QuENA C-version were 0.945, 0.979, 0.968, and 0.053, respectively, indicating a good model. The indices in the P-version were 0.911, 0.939, 0.905, and 0.108. Its RMSEA, however, was beyond the close fit criteria, 0.08. As a result, the model in the data derived from the patient’s self-evaluation did not fit perfectly. The standardized factor loadings and correlation between factors of the QuENA provided by the caregivers are shown in Figure 2. Higher factor loadings indicated that TD symptoms explained a large portion of the variance. The AUC of the C-version was 0.775 (95% confidence interval [CI] = 0.706-0.844) and that of the P-version was 0.705 (95% CI = 0.628-0.783). As shown in Table 4, the optimal cutoff point was 7/8 for the C-version and 1/2 for the P-version and as such the prediction of GL was 78% and 71%, respectively.

Figure 2.

Confirmatory factor analysis for the hybrid model of topographical disorientation (caregiver version of the QuENA). Factor loadings and correlations between factors were based on caregiver’s report. One-way arrows indicate factor loadings and 2-way arrows indicate correlations between factors. Standardized residual variances (e) are listed below each error box (e1 to e10). Q01 to Q10 are the items of the QuENA (Appendix).

Table 4.

Optimal Cutoff Points of the QuENA

	Cutoff	Sensitivity	Specificity	Youden index (J)^a
QuENA-C	6/7	0.726	0.714	0.440
	7/8	0.717	0.750	0.467
	8/9	0.632	0.830	0.462
QuENA-P	0/1	0.756	0.500	0.243
	1/2	0.695	0.607	0.302
	2/3	0.571	0.696	0.267

Abbreviation: QuENA, Questionnaire on Everyday Navigational Ability; P, patient; C, caregiver.

^aYouden index (J) = sensitivity + specificity − 1.

Discussion

The results of this study are important for several reasons, not least because this is the first syndrome-oriented and theory-driven questionnaire to assess TD in PwAD. Moreover, the QuENA is a reliable and valid questionnaire to evaluate the possibility of GL in PwAD. Although the hybrid model of TD was derived from case reports with focal brain damage, we demonstrated that the model is suitable for PwAD through caregivers’ observation. Most importantly, the CFA provided support for the 4 factors in the TD symptoms of PwAD. This cross-sectional study also revealed the value of the QuENA to discriminate between PwAD who have experienced GL and those who have not. Even though the cutoff of the C-version was higher than that of the P-version, the score was low considering the maximum score of 30 of the QuENA. The total score of the QuENA was the sum of the 4 types of TD.^2,5 According to previous studies, GL occurs after any type of TD,¹¹ and therefore the low cutoff score of the C-version is reasonable. Moreover, with better discriminating power of GL, the C-version is recommended as a primary tool to evaluate the possibility of GL and is suitable for the description of TD symptoms. Conversely, the P-version is suitable for testing the awareness of patients regarding their TD symptoms. When QuENA is used as a tool to detect TD symptoms in PwAD and showed that a patient actually underestimates their TD, caregivers should pay more attention for the risk of GL.

In addition, the finding of a discrepancy in the appraisal of spatial navigational ability between patients and their caregivers is clinically important. The discrepancy is more obvious in the multiple-GL group, which accounted for one third of all GL, indicating that poor insight may lead to repeated GL. It is also consistent with previous studies that low awareness toward cognitive impairments (anosognosia) may increase the risk of dangerous behaviors.³⁹ From our previous study, not every PwAD who experienced first time GL would be watched more closely by his or her caregivers. Some of the caregivers did nothing at all even after several occurrences of GL events.⁴⁰

Finally, the QuENA is recommended to assess PwAD. In fact, the TD symptoms may occur in some PwAD before other cognitive functions decline.⁴¹ In this study, the clinical severity of the PwAD was mild to moderate and no differences were detected in any of the demographical or clinical variables between the PwAD with GL and those without. Similarly, no difference was detected in the CASI or MMSE between the GL and non-GL groups. The TD symptoms of PwAD usually manifest through landmark agnosia, impairment in route knowledge, or attention deficit^5,12,14 and may occur after damage to different cerebral areas. Based on the dissociation of TD and GL from general cognitive decline,⁹ the QuENA is a good tool to fill the gap between the traditional tests and the actual spatial navigational ability in familiar environments. Furthermore, we also recommend that PwAD, in particular those pinpointed as being at risk by the QuENA, should improve their familiarity of their neighborhood through a cognitive rehabilitative program or become more aware of their TD through real-world testing. They may also learn to use compensatory or coping strategies once GL has occurred, according to the deficits (higher scores) from the QuENA.

Limitations of this study are addressed as follows. First, although in this cross-sectional study, QuENA easily differentiates PwAD with GL from those without, further longitudinal research is needed to show the progression of TD in PwAD and to find the factors that can predict GL. Second, future studies are also necessary to compare the results of QuENA with way-finding experiments to establish the external validity. Finally, the study lacked neuroanatomical correlates, such as atrophies in structural neuroimages or perfusion deficit or hypometabolism in functional neuroimages.

In conclusion, the QuENA, as a theoretical driven questionnaire, is feasible, reliable, and valid to assess TD symptoms in PwAD. It may be useful for warning caregivers of the risk of GL in such patients.

Footnotes

Appendix A

Appendix B

Acknowledgments

The authors thank Jo Yung-Wei Wu and Colin McDonald for editing this manuscript.

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

The authors received no financial support for the research, authorship, and/or publication of this article.

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