Neurocognitive Disorder Diagnoses Matter: A Brief Report on Caregiver Appraisal of Driving Ability

Abstract

Background: Age-associated neurocognitive disorders (NCDs) are associated with progressive loss of abilities for instrumental activities of daily living, including driving. This study assesses the impact of NCD diagnosis, while controlling for reported level of cognitive impairment, on family caregiver judgment of driving safety. Method: An intervention sample of 152 intergenerational caregivers who assist an older adult with medical tasks was used. Caregiver’s pre-intervention response to a single item of confidence in the older adult driving was used to determine judgment of driving ability. Cognitive impairment was assessed using caregivers’ report for Clinical Dementia Rating (CDR) Sum of Boxes score. Results: Older adults with a diagnosis were rated as less capable of driving safely than those without a diagnosis, while controlling for reported level of cognitive impairment. Conclusion: Results of this study highlight the importance of NCD diagnosis on caregiver judgments. Results of this study have implications for health care and driving safety.

Keywords

measurement cognitive function function/functional status activities of daily living (ADL)dementia alzheimer disease

Introduction

Driving safety and cognitive impairment in older adults are inversely correlated across on-road tests, nonroad tests, and care partner reports (Reger et al., 2004). Roughly, one third of older adults diagnosed with some form of dementia continue driving, however, with half of these individuals driving for 3 or more years post diagnosis (Silverstein, 2008).

Some evidence shows that older adults with early cognitive impairment can be safe drivers (Eby & Molnar, 2010); this ability declines rapidly, especially, for those diagnosed with Alzheimer disease (Duchek et al., 2003). Cognitive functioning is an important piece of driving safety, and evaluation of cognitive impairment can give some indication of fitness to drive (Dickerson, Reistetter, & Trujillo, 2010).

Identifying the appropriate time for an older adult with cognitive and other functional impairments to stop driving is a difficult and necessary task. Self-report of driving safety among these individuals is often inaccurate (Iverson et al., 2010). The neuropsychological profiles of older adults with dementia who are driving and no longer driving are similar (Carr, Shead, & Storandt, 2005), indicating that on-road assessment or informant reports are needed to evaluate driving safety. Older adults who are cognitively impaired and restrict driving rarely ascribe these changes to their impairment or take the final step of independently discontinuing driving (Meng & Siren, 2015). It is oftentimes left to involved family members to express concern and request an evaluation (Iverson et al., 2010). When families reported medically impaired older drivers to a state licensing agency, physician evaluations agreed with their concerns 81% of the time (Meuser, Carr, Unger, & Ulfarsson, 2015). Despite some variability in agreement across sources, consensus panels of experts recognize family reports of driving concerns as important in identifying medically unfit drivers (Rapoport et al., 2014).

Identifying what factors influence a care partner’s rating of driving safety is a key step toward improving public education regarding older driver safety. Diagnostic labels can have negative outcomes such as discrimination and overprotection, especially, with stigmatized diagnoses such as dementia (Garand, Lingler, Conner, & Dew, 2009). Formal diagnosis of a neurocognitive disorder (NCD), however, can also function as a signal for increased monitoring and collaborative care planning within families. This study investigates the impact of NCD diagnoses on family care partner ratings of driving safety. We hypothesize that, when controlling for care partner ratings of cognitive and functional impairment severity, older adults diagnosed with a NCD will be described by a family member as less capable drivers than undiagnosed older adults.

Method

Participants

Data from an intervention study of family care partners were used for this project. This data set included 152 females between 18 and 69 years of age who assisted an older adult from an earlier generation with health care (Steffen, Epstein, George, & MacDougall, 2016). Care recipients were community-dwelling older adults (60+ years) and biological or “chosen” relatives of the participants. Participants were required to have attended or transported the care partner to a medical appointment within the previous year and assisted with another task related to medication. Participants received a US$25 gift card as compensation after completing pre-intervention surveys.

Procedures

Family care partners interested in the study provided informed consent and completed a brief screening survey to determine eligibility. Participants then completed four brief online surveys that included all measures listed below, among others relevant to the larger intervention study. These surveys were completed via online computer-assisted survey software. Only pre-intervention data were used in this project. The (University of Missouri - St. Louis) Institutional Review Board provided approval for this study (506921).

Measures

Cognitive and functional impairment

The Clinical Dementia Rating (CDR) Scale is a semistructured interview involving a patient and an informant that evaluates impairment across six domains of cognitive and functional performance applicable to Alzheimer disease and related dementias (Morris, 1993). Scores range from 0 to 3 with higher scores indicating more impairment. The Sum of Boxes scoring method involves summing the individual CDR domain scores for a possible range from 0 to 18 (O’Bryant, Waring, & Cullum, 2008). This study used an informant-based, multiple choice version of the CDR that has been validated for staging cognitive and functional impairment associated with dementia (Duara et al., 2010). This method assesses each domain with a single-item rating of impairment. In this study, the CDR analog demonstrated good interitem reliability (α = .94); CDR Sum of Boxes scores for older adults with and without NCD diagnoses are shown in Table 1.

Table 1.

Measures (N = 152).

Variable	N (%)	Range	M (SD)
NCD diagnosis
“If this individual has been diagnosed with dementia, what was the primary diagnosis?”
Alzheimer disease	49 (32.4)
Vascular/stroke-related	8 (5.26)
Parkinson disease	2 (1.32)
Lewy body	2 (1.32)
Frontotemporal	1 (0.66)
I do not know which type	24 (15.79)
No diagnosis	66 (43.42)
CDR Sum of Boxes Score		0-18	6.01 (4.75)
With dementia diagnosis (n = 86)		1.5-18	8.63 (4.30)
No dementia diagnosis (n = 66)		0-13.5	2.58 (2.71)
Variable	DiagnosedN (%)	UndiagnosedN (%)
Driving ability
“I trust this older adult to drive, alone, and pick up an 8-year-old child (e.g., grandchild, other relative) at the end of the school day and drive the child home safely.”
Strongly disagree	65 (75.6)	29 (43.9)
Disagree	9 (10.5)	6 (9.1)
Neither agree nor disagree	8 (9.3)	7 (10.6)
Agree	3 (3.5)	14 (21.2)
Strongly agree	1 (1.2)	10 (15.2)

Note. NCD = neurocognitive disorder; CDR = Clinical Dementia Rating.

NCD diagnosis

Care partners reported whether their older family member had been diagnosed with a NCD. Participants completed a checklist of current medical conditions among a number of other demographic items. Response options and results are shown in Table 1. For this study, each type of diagnosis was treated equally to divide the sample into two groups—diagnosed and undiagnosed—which were respectively coded as “1” and “2.” Responses of “I do not know which type” were placed in the diagnosed group.

Driving ability

Care recipient driving ability was rated with level of agreement to a single item shown in Table 1. Given the desire for a brief measure, this single item was used in place of longer standardized measures.

Results

Demographic information of the participants and care recipients are available in Table 2. The care recipients averaged 81.18 years old and were mostly parents or stepparents (80.92%) and no longer driving (65.13%). Health conditions of care recipients included hypertension (63.16%), arthritis (50.66%), and cardiovascular disease (36.18%). Care partners ranged in age from 23 to 72 years (M = 50.23, SD = 11.05). On the CDR Sum of Boxes, nondrivers were rated as more severely impaired (M = 7.88) than current drivers, M = 2.50; t(149.90) = −9.416, p < .001. The relationship between driving status and NCD diagnostic status was also significant, χ²(1, N = 152) = 16.94, p < .001. Older adults with a NCD diagnosis were more likely to be nondrivers, so driving status was included as a covariate in analyses.

Table 2.

Caregiving Context (N = 152).

Variable	N (%)	Range	M (SD)
Care partner demographics
Age		23-72	50.23 (11.05)
Years of formal education		12-25	15.64 (2.27)
Caregiving duration (in months)		0-360	50.66 (56.50)
Number of IADLs care partner helps with		0-8	5.52 (2.22)
Care recipient demographics
Age		61-99	80.18 (8.23)
ADL impairment (# of activities)		0-6	2.24 (2.35)
Female gender	109 (71.71)
Relationship to care partner
Mother/in-law/stepmother	88 (57.89)
Father/in-law/stepfather	35 (23.03)
Close friend/neighbor	14 (9.21)
Other relative	15 (9.87)
Care recipient driving behaviors
Current driver	53 (34.87)
Driven alone in past 14 days	48 (29.61)

Note. ADL = activities of daily living; IADL = instrumental activities of daily living.

#: number of activities which are impaired

The driving safety rating was significantly correlated with CDR Sum of Boxes scores (r = –.47, p < .001). Chi-square analyses showed statistically significant relationships between the driving safety rating and both NCD diagnostic status, χ²(4, N = 152) = 26.77, p < .001, and driving status, χ²(4, N = 152) = 98.70, p < .001. To clarify these relationships, a hierarchical linear regression was used to evaluate our hypothesis that older adults diagnosed with a NCD would be rated as less capable drivers by care partners than those without a NCD diagnosis. As shown in Table 3, the regression model included three blocks, with CDR Sum of Boxes scores in Block 1, driving status added in Block 2, and NCD diagnostic status added in Block 3. All three models were significant, with added value at each step. The final block of the regression model was a significant predictor of driving safety rating, F(3, 148) = 67.51, p < .001, R² = .58. This model was significantly improved over the second step of the model, R²Δ = .02, p = .01). NCD diagnostic status was a significant predictor in the final model (B = –.20, p = .01); driving status remained a significant predictor but CDR Sum of Boxes scores did not (p = .69). These results suggest that individuals diagnosed with a NCD were rated as poorer drivers by care partners and that this rating mattered above and beyond care partner ratings of cognitive and functional impairments associated with dementia. Furthermore, this difference is not fully accounted for by differences in driving status between groups.

Table 3.

Hierarchical Regression Analyses for Rating of Driving Safety (N = 152; Hypothesis 4).

Predictor variables	B	R	R²/Adj. R²	ΔR²	F	ΔF
Step 1		.47	.22/.21		41.94***
CDR SOB	−.47***
Step 2		.75	.56/.55	.34	92.92***	112.68***
CDR SOB	−.09
Driving status	−.69***
Step 3		.76	.58/.57	.02	67.51***	7.99**
CDR SOB	.03
Driving status	−.69***
NCD diagnosis	−.20**

Note. CDR = Clinical Dementia Rating; SOB = Sum of Boxes; NCD = neurocognitive disorder.

p < .05. **p < .01. ***p < .001.

Discussion

Results from this study showed that diagnosis of a NCD is an important factor for care partner ratings of an older adult’s driving ability; these are influenced by NCD diagnosis above and beyond their impression of the severity of the care recipient’s cognitive and functional impairment or driving status.

This importance placed on diagnosis above subjective rating of impairment suggests that care partners are influenced by external factors when making driving safety decisions. Care partners may feel more inclined to select a lower rating because of converging evidence for cognitive and functional impairment. Alternatively, the diagnosis may carry significance for care partners such that they consider it to be a red flag for driving safety.

All care recipients in this study had at least one chronic health condition that necessitated help with daily medical tasks. Presence of a NCD stood out as informative despite this need for medication management, suggesting it has an impact on care recipient ratings beyond these other limitations.

This finding is relevant for how health care professionals and care partners approach decision making related to driving safety. A brief discussion of driving safety with care partners should follow NCD diagnoses. Linking these individuals to resources and education about driving safety is an important part of diagnosis, along with clarifying that diagnosis of a NCD, alone, is insufficient for evaluating driving skills and safety. Domain-specific assessment in cases of mild NCD is indicated to determine ability levels, rather than assuming global deficits (Okonkwo et al., 2009). Assessment with a driving rehabilitation specialist is recommended for these important safety decisions (Betz et al., 2014; Carr, Duchek, Meuser, & Morris, 2006).

The single item used to determine driving capability in this study assesses family perceptions differently than previous studies. Informants have previously been shown to be lenient in driving behavior ratings of cognitively impaired older adults (Brown et al., 2005). The question used in this study involves an emotional component that might yield more stringent ratings than asking solely about driving behaviors. Using this question in conjunction with more standard driving questions might help gather a more comprehensive view of driving ability.

This study includes several limitations. No other driving ratings were collected for comparison, including self-reports or physician reports or performance on a driving test. Most care recipients were no longer driving. Among those no longer driving, reasons for this stoppage were not collected, and relevant variation could exist among the cause for retirement from driving. We also relied on family ratings of functional domains assessed by the CDR as our only measure of cognitive and functional limitations associated with dementia; additional measure of cognitive impairment would have improved our ability to interpret study findings.

Results from this study suggest that physicians should be aware of the impact of NCD diagnosis on family perceptions of functional independence. Care partners should be instructed to not assume global impairment and to pursue domain-specific assessment for major decisions, such as driving ability.

Footnotes

Declaration of Conflicting Interests

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

Ethical Approval

IRB Human Subjects Approval number: 506921

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This project was supported by the University of Missouri–St. Louis Express Scripts Research Award

ORCID iD

Nicholas E. Schmidt

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