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1 Section of Geriatric Medicine, 2 Department of Psychiatry, and 3 Section of General Internal Medicine, Yale University, New Haven, Connecticut.
4 Division of Geriatrics, Leonard Davis Institute of ealth Economics, Center for Bioethics, Center for Clinical Epidemiology and Biostatistics, Alzheimer's Disease Center, and Institute on Aging, University of Pennsylvania, Philadelphia, Pennsylvania.
Address correspondence to Jason Karlawish, MD, University of Pennsylvania Institute on Aging, 3615 Chestnut Street Philadelphia, PA 19104. E-mail: Jason.Karlawish{at}uphs.upenn.edu
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Methods. In 154 mild-to-moderate AD patients and 62 cognitively intact patients, we measured self-reported distress, on a five-point Likert scale, after 45 minutes of cognitive testing. Using multivariate logistic regression, we then examined whether demographic factors, level of education, depressive symptoms, cognitive performance, perceived test difficulty, and perceived test performance compared to 10 years ago were predictive of self-reported distress.
Results. The prevalence of any self-reported distress in patients with AD was 70% compared to 47% in patients without AD (p <.001). Of persons with AD, bivariate analyses revealed that those who reported more difficulty with testing (relative risk [RR] 1.32; 95% confidence interval [CI], 1.25–1.37) and felt that they performed worse than 10 years ago (RR 1.21; 95% CI, 1.07–1.30) were at increased risk for reporting more distress. Paradoxically, cognitive performance was a weak predictor of distress, with only language performance demonstrating an association (RR 0.95; 95% CI, 0.89–0.99). Adjustments for demographic factors, education, dementia severity, or depressive symptoms in the multivariable analyses did not alter these relationships.
Conclusion. Cognitive tasks provoke more distress in patients with mild-to-moderate AD compared with persons who do not have dementia. Predictors of distress are more closely related to patient awareness about test difficulty and performance, rather than actual test performance.
Key Words: Alzheimer's disease • Neuropsychiatric testing • Dementia • Distress
As valuable as cognitive testing is for diagnosis, treatment, and staging, clinical experience suggests that such cognitive tasks may also negatively impact a patient's psychological state, especially among patients who are aware of their cognitive impairments. Although patients with dementia often lose awareness of their cognitive deficits (5), the severity of loss of awareness spans a spectrum and does not have a clear association with the severity of cognitive deficits (6).
Few empiric studies describe the relationship between cognitive testing and distress in the patients who undergo it (7). By quantifying this association and defining the demographic and disease factors that predict this distress, clinicians may generate valuable information that could alter the management of patients with AD in at least two ways. First, patients who experience distress when exposed to a standardized cognitive challenge also may be at greater risk for experiencing high levels of distress when performing more ecologically valid cognitive tasks, such as managing one's finances or preparing a meal. Second, clinicians who identify factors that predict distress after cognitive testing can anticipate this symptom and develop ways to mitigate its impact.
This study represents the first step in a line of investigation designed to determine the clinical value of measuring the psychological responses patients have to cognitive tasks. We examined the prevalence and severity of self-reported distress after a cognitive test battery in patients with and without AD. Furthermore, we determined patient characteristics associated with this distress, and tested whether actual test performance or patient perceptions of test performance are related to the degree of distress that patients report.
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METHODS |
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Data Collection
As part of routine annual assessments, a trained research assistant administered a cognitive test battery to participants. The battery takes 45 minutes to complete and consists of the following measures: Verbal Fluency Test (9), Boston Naming Test (10), Folstein MMSE, Word List Memory Task (11), Delayed Word List Recall (11), Word List Recognition (11), Logical Memory 1 (12), Clock Drawing Task (13), Digit Symbol Test (14), and Logical Memory 2 (12). Clinicians collected data on age, race, ethnicity, and years of education, and assessed self-reported depressive symptoms using the 15-item Geriatric Depression Scale (GDS) (15). Knowledgeable informants for the participants with AD also completed the Dementia Severity Rating Scale (DSRS) (16).
Self-Reported Measures
Immediately following the cognitive test battery, a research assistant asked the participants, "What was it like answering these questions? Would you say... not at all distressing, mildly distressing, moderately distressing, very distressing, or extremely distressing?" To assess for perceptions of test difficulty, participants were also asked, "What was it like answering these questions? Would you say... very easy, easy, somewhat easy, somewhat difficult, difficult, or very difficult?" To assess the participants' level of awareness in their test performance, they were asked, "How is your ability to do these tests compared to ten years ago? Better than ten years ago, the same as ten years ago, or worse than ten years ago?" Although this measure does not fully capture a patient's insight, it is a measure that is clinically plausible as dementia is, by definition, a change in cognitive performance from a person's baseline abilities.
Statistical Analysis
Because patients rarely reported having extreme distress, we collapsed the "very" and "extremely" distressing categories into a single "severe" category. All subsequent analyses evaluated the degree of self-reported distress using this ordinal four-category scale. For similar reasons, we collapsed patients' perceptions of test difficulty into two categories: "very to somewhat easy" and "very to somewhat difficult." To enhance the clinical interpretation of patient perceptions of historical test performance, we combined the categories of patients who reported having the "same" or "better" test performance compared to 10 years ago. For patients with AD, we operationalized that reporting test performance that was "worse than ten years ago" signified adequate insight with respect to their cognitive abilities. Meanwhile, responses of "same" or "better" test performance signified impaired insight, as persons with AD, by definition, have a clinically significant decline in their cognitive performance.
The neuropsychological tests were separated into four cognitive domains: language (Boston Naming, Verbal Fluency), memory (Word List Memory, Word List Recall, Word List Recognition, Logical Memory 1 and 2), processing speed (Digit Symbol Substitution), and visual-spatial ability (Clock Drawing). Raw scores for the tests in each domain were converted into z scores and summed to form four composite variables. A composite variable, representing the sum of all test z scores, was also created to provide a measure of overall test performance in patients with AD (17).
For comparisons between AD and intact patients, we used the chi-square statistic for categorical data, an unpooled Student t test for normally distributed data, and the Wilcoxon rank sum test for variables with non-normal distributions as determined by the Shapiro–Wilk test. Bivariate and multivariable analyses were assessed using ordinal logistic regression (18). All odds ratios were converted to relative risk (RR) estimates, as the presence of self-reported distress was common (>10%) (19).
Using a manual stepwise procedure, we performed two sets of multivariable analyses. First, we examined the relationship between perceptions of test difficulty and test performance on self-reported distress given the potential confounding factors of age, gender, race, education, dementia severity, actual test performance, and GDS score. Second, we evaluated the relationship between test performance in each of the specific cognitive domains and self-reported distress. In these models, domain performance was controlled for age, gender, race, education, dementia severity, and GDS score. Variables included in the final models were either statistically significant at the p <.05 level or were associated with a >10% change in the parameter estimate of the independent variable or variables of interest. All analyses were performed using SAS (version 9.1; SAS Institute, Inc., Cary, NC).
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RESULTS |
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Predictors of Distress in Patients with AD
In the bivariate analyses (Table 2), patients with AD who perceived the testing to be more difficult had a significantly greater risk of reporting more distress (RR 1.32; 95% confidence interval [CI], 1.25–1.37) than did those who did not find testing difficult. AD patients who felt that they performed worse than 10 years ago (RR 1.21; 95% CI, 1.07–1.30) also had an increased risk of reporting more distress than those who felt that they did the same or better than 10 years ago. Patients who admitted having "more problems with memory than most" on the GDS, however, did not have a greater risk of reporting more distress (RR 1.12; 95% CI,.95–1.24). Of the four cognitive domains shown in Table 3, we observed a small but statistically significant bivariate association between decreased language ability and self-reported distress (RR 0.95; 95% CI, 0.89–0.99). There was no association between distress and performance on the MMSE. Within the cognitively intact group, however, there were no significant bivariate associations between demographic factors, cognitive test performance, perceptions of test difficulty or test performance, and increasing levels of reported distress.
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DISCUSSION |
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These findings have two clinical implications. First, neuropsychological testing is not necessarily a benign exercise, but may have short-term psychological effects. These effects may generate anxiety and potentially influence patients' compliance with follow-up, as is observed with patients who experience distress following testing for other diseases (20). Knowledge of this distress, however, provides clinicians with the opportunity to prepare patients and family members for the risks associated with testing and to institute interventions after testing to minimize its negative effects. Furthermore, if clinicians assess the risk factors for distress, they may be able to categorize their patients into those who are at risk for distress. Specifically, persons who endorse cognitive decline and find cognitive testing difficult versus those who do not endorse these features are likely to experience excessive levels of distress from cognitive testing.
Second, patients with AD who experience distress during testing may also experience similar distress while performing other functionally relevant tasks, such as balancing a checkbook or following a recipe. These tasks simulate the same kind of cognitive challenges experienced in neuropsychological testing. Therefore, self-reported distress during testing may serve as a marker for those patients with AD who may have a more chronic exposure to distress. Further research is necessary to show whether this is in fact the case. The absence of data on the outcomes associated with symptoms of distress in patients with AD represents a clinically relevant area of future research.
Regarding risk factors for distress, insight into cognitive problems emerged as a predictor. At least 60% of the patients with AD reported that they performed "worse" on the testing compared to 10 years ago. Given that insight has also been associated with a greater likelihood of being capable of giving consent for an AD treatment (21), our results suggest that one may derive both scientific and clinical value from assessing patient insight.
Paradoxically, cognitive test performance was minimally associated with experiencing distress. Only performance in language ability was associated with distress. Furthermore, our informant-based measure of dementia severity, the DSRS, also failed to show an association with self-reported distress. This finding suggests that the presence of distress may not necessarily be linked to the severity of either functional or cognitive impairments. One potential explanation for this is that the patients with AD who perceived greater test difficulty and had greater insight into their deficits had small declines in cognitive ability for the tests used in this study. Tests of other cognitive domains or with a higher sensitivity for detecting change may have revealed a stronger association between insight and distress and actual performance and distress.
Although there was a surprisingly modest relationship between actual cognitive performance and self-reported distress, our findings remain consistent with existing hypotheses linking exposure to stress with hippocampal (22,23) and prefrontal cortex (24) dysfunction. Namely, we observed an association between language ability, a cognitive function associated with the prefrontal cortex (25), and distress. We did not, however, demonstrate a relationship between performance on memory domain tests and self-reported distress. Differences in the types of tests used to measure episodic and declarative memory in previous studies may, in part, explain the absence of this observation. Additionally, given the high distribution of scores in the lower ranges for the tests of Logical Memory 1 and 2 and Word List Recall (Table 1), floor effects may have limited our ability to measure a range of memory function.
The absence of baseline measurements of self-reported distress taken prior to the cognitive testing is also a study limitation. It remains unknown how closely perceptions of distress after testing differ from those present before testing. Lastly, we recognize that our findings represent data collected from a single site. Patient populations with different characteristics and alternate clinical settings may respond differently to cognitive testing.
Overall, these results show that cognitive tasks provoke more distress in patients with mild-to-moderate AD compared with persons who do not have dementia, and that this distress is more closely related to patient awareness about test difficulty and performance than actual test performance or dementia severity. Consequently, clinicians should consider the value of monitoring patients' insight into their cognitive ability, as well as test performance, to help gauge the psychological effects of the disease. Future studies are needed to clarify the prognostic significance of distress related to testing and to determine appropriate interventions, if any, which may benefit these patients.
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Received May 29, 2007
Accepted December 29, 2007
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| Journals of Gerontology Series B: Psychological Sciences and Social Sciences | |
