The ability of the Dementia Rating Scale to predict everyday functioning

Archives of Clinical Nmmp3yrhology, Vol. 8. pp. 44%460,1!293 a3al-6117t?x3 $6.00 + .xl

Printed in the USA. All rights rcsavcd. Copyright (B 1993 National Academy of Ncurq~ychology

The Ability of the Dementia Rating Scale

to Predict Everyday Functioning

Jodi D. Nadler, Emily D. Richardson, and Paul F. Malloy

Butler Hospital and Brown University

Mary E. Marran and Mary E. Hostetler Brinson

Butler Hospital

The Dementia Rating Scale (DRS) is a brief neuropsychological assessment battery designed to assess five areas of cognitive functioning in the elderly. The relationship between DRS performance and everyday functioning was examined for 50 psychogeriatric patients. Every&y functioning was assessed with a standardized performance measure examining self-care, safety, money management, cooking, medication administration, and community utilization. Regression analyses were conductedfor each of the six jimctional domains. In addition, correlations between the DRS subscales and the functional areas were computed. Results revealed significant predictive relationships (p < .Ol) between performance on the DRS and most functional domains. The multiple Rs ranged from .S2-.70, accounting for 27% to 49% of the variance. The Initiation/Perseveration subscale was most heav- ily weighted in each analysis. Significant correlations were obtained between sub- domains of cognition and mast fimctional areas. The findings provide evidence of relationships between DRS peflormance and functional ability

Neuropsychologists are often asked to make judgments regarding a patient’s ability to function in everyday life. Such requests are made with the underly- ing assumption that particular cognitive processes, such as memory or visu- ospatial abilities, are required for adequate performance of everyday activities. Hence, a patient with severe cognitive deficits would be expected to demon- strate difficulty performing functions of everyday living.

This paper was originally presented at the eleventh annual meeting of the National Academy of Neuropsychology, Dallas, Texas, November 1991.

Address correspondence to: Emily D. Richardson, PhD, Butler Hospital, 345 Blackstone Blvd., Providence, RI 02906.

449

450 J. D. Nadler et al.

Evaluation of everyday living skills is particularly important for elderly patients, for whom this information is used to determine appropriate living situations, environmental supports, and level of daily activity. A number of studies have attempted to examine the relationship between neuropsychological assessment and everyday functioning in the elderly (Dunn, Searight, Grisso, Margolis, & Gibbons, 1990; McCue, Rogers, & Goldstein, 1990; Reed, Jagust, & Seab, 1989; Skurla, Rogers, & Sunderland, 1988; Warren, Grek, Conn, Herrmann, Icyk, Kohl, et al., 1989; Weintraub, Baratz, & Mesulam, 1982). The overall findings suggest a moderate relationship between measures of neuropsychological functioning and everyday abilities. However, the findings have varied somewhat across studies, due in part to varying strategies of assessment for both neuropsychological functioning and everyday abilities. Measurement of everyday functioning has included self-report questionnaires (DeBettignies, Mahurin, & Pirozzolo, 1990; Kuriansky, Gurland, & Fleiss, 1976), informant ratings (DeBettignies et al., 1990; Kuriansky et al., 1976; Reed et al., 1989; Weintraub et al., 1982) and performance measures (Dunn et al., 1990; Mahurin, DeBettignies, & Pirozzolo, 1991; McCue et al., 1990; Skurla et al., 1988; Warren et al., 1989). Studies comparing the various methods of measuring everyday abilities have demonstrated only moderate relationships between them (DeBettignies et al., 1990; Kuriansky et al., 1976). However, one would expect that actual performance measures would provide the most valid assessment because the individual is actually being observed while engaging in the activity in question.

Within the domain of neuropsychological assessment, some studies have utilized brief cognitive measures (Reed et al., 1989; Skurla et al., 1988; Warren et al., 1989), whereas others have used more lengthy, comprehensive batteries (Dunn et al., 1990, McCue et al., 1990). Skurla et al. (1988) examined the association between the Short Portable Mental Status Questionnaire (SPMSQ), the Clinical Dementia Rating Scale (CDR), and a performance measure of activities of everyday living (ADL). The SPMSQ consists of 10 orientation questions assessing mental status, whereas the CDR is a comprehensive rating tool that provides a single score of overall functioning based on

medical, psychiatric, family, and psychosocial evaluations. The ADL measure consisted of four experimental tasks specifically measuring dressing, meal preparation, telephoning, and purchasing. Nine patients with Alzheimer’s Disease (mean age 65 years, mean education 14.7 years) and nine age- matched controls (mean education 16 years) were evaluated and correlations among the measures were computed. Although significant positive correlations were obtained between the clinical rating scale and the ADL tasks (r = .59), and between the clinical rating scale and the mental status questionnaire (r = .60), the association between the mental status questionnaire and the ADL measure was not significant (r = .40).

In contrast to Skurla et al. (1988). Warren et al. (1989) did find relationships between cognitive functioning and everyday abilities utilizing an alter-

Dementia Rating Scale and Everyday Functioning 451

native mental status questionnaire. With a sample of forty-five elderly subjects (aged 67 to 97) who exhibited a range of mental abilities and degrees of independent living, they obtained a significant correlation (r = 31) between the Mini Mental State Exam (MMSE; Folstein, Folstein, & McHugh, 1975) and everyday functioning (as measured by both a direct assessment of everyday abilities and an informant rating questionnaire about activities of daily living and physical self-maintenance). Reed et al. (1989) reported similar results demonstrating a significant predictive relationship between the MMSE and everyday functioning as measured by a family report instrument.

These results suggested that a brief cognitive measure may be a useful predictor of daily functioning. The difference in findings between the Skurla et al. (1988) and the Warren et al. (1989) and Reed et al. (1989) results may be attributed, at least in part, to measurement differences between the studies. For example, the MMSE has a larger range of scores than the SPMSQ. In addition, whereas the SPMSQ measures mostly orientation, the MMSE measures a wider range of abilities. This suggests that a broader assessment of cognitive function may serve to enhance predictive capabilities of everyday functioning.

These studies, using mental status questionnaires, although providing important information, involve only a cursory evaluation of cognitive domains. In addition, they typically lack any assessment of critical domains of cognitive abilities, such as frontal system functions. Consequently, the instruments provide limited information for neuropsychologists. Furthermore, mental status questionnaires, such as the widely used MMSE, have been shown to underestimate cognitive impairment in psychiatric patients (Faustman, Moses, & Csemansky, 1990).

A study incorporating a comprehensive neuropsychological instrument was conducted by Dunn et al. (1990). They investigated the relationship between neuropsychological test performance and everyday functioning using the Halstead-Reitan Neuropsychological Battery (HRNB), and utilizing a measure that includes a structured interview and a performance evaluation of everyday functioning. Their sample consisted of 40 elderly patients with sus- pected dementia (mean age 69.6 years). Results of a canonical analysis revealed a high canonical correlation (.82) between the two sets of measures. Follow-up multiple regression analyses revealed significant predictive relationships between neuropsychological test performance and overall level of everyday functioning. Individual areas of everyday functioning, with the exception of the abilities to utilize transportation and acquire money, were also significantly predicted by the neuropsychological test performance. However, with few exceptions, significant relationships were not found between any given test of neuropsychological function and a specific domain of everyday functioning. Only two HRNB measures, Speech Sounds Perception and the Seashore Rhythm Test, were significantly related to everyday functioning.

452 J. D. Newer et al.

Although the Dunn et al. (1990) study demonstrated significant relationships between neuropsychological performance and everyday functioning, their results should be viewed with caution due to the unacceptably low ratio of subjects to variables, approxima~ly two to one, thereby bringing into question the reliability of the coefficients (Tabachnick & Fidell, 1989). An additional criticism of the study involves the practical clinical use of the HRNB in elderly populations. The length of the HRBN makes it a dif~c~lt procedure to use with elderly patients, who tend to have increased susceptibility to fatigue (Albert, 1981).

Other studies have used neuropsychological assessment procedures that are comprehensive, yet designed for use with the elderly. McCue et al. (1990) examined the relationships between a shortened version of the Luria-Nebraska Neuropsychological Battery (LNNE-S) and a performance measure of everyday functioning modified for assessment of dementia in the elderly. The performance measure of everyday functioning evaluated abilities within four clas- sifications: personal self-care, mobility, physically oriented instrumental self- care, and cognitively oriented instrumental self-care. Their subjects were 58 geropsychiatric inpatients aged 60 to 91 (mean age 74 years, mean education 10 years). Relationships between the LNNB-S scales and performance of everyday functions were examined using multiple regression procedures and univariate correlational methods. The LNNB-S significantly predicted physically and cognitively oriented ins~ment~ self-care activities, but not personal self-care tasks and mobility. Obtained Pearson correlations between the LNNB-S scales and personal self-care tasks (e.g., feed self) were low, despite statistical significance. Fewer significant correlations were seen for mobility (e.g., lie down on a bed). Moderate correlations were seen for physically oriented ins~ment~ activities (e.g., wash dishes). Cognitively oriented aspects of instrumental self-care (e.g., use of a telephone) produced the largest correlations with neuropsychological measures, particularly those assessing memory.

The McCue et al. (1990) study demons~a~d signi~c~t predictive relationships between neuropsychological performance and performance of everyday functions that presumably require more complex cognitive functioning. It also

revealed associations between specific neuropsychological abilities and areas of everyday functioning. However the neuropsychological measure used, the LNNB-S, is a modi~cation of a larger, general adult battery, rather than a battery developed specifically for use with the elderly. Consequently, this rela- tively new battery may not be widely recognized and used as an assessment tool with the elderly. Therefore, a study employing a commonly used battery specifically developed for use with the elderly is warranted.

Weintraub et al. (1982) conducted a study with the Dementia Rating Scale (DRS; Mattis, 1988), a widely used neuropsychological test battery specifically designed for assessing elderly patients. They compared performance on the DRS, the Block Design subtest of the WAIS (Wechsler, 1955), and a clock- drawing task with responses to a questionnaire of everyday functioning com-

Dementia Rating Scale and Everyahy Functioning 453

pleted in interview with a family member. Seven patients, aged 54 to 72, in the early stages of Alzheimer’s disease were studied. Their results revealed some similarities between performance on cognitive measures and ratings of everyday functioning. However, the extremely small number of cases (n = 7), as well as the absence of an actual performance measure of everyday functioning, made the findings difficult to interpret. A more systematic study of this relationship, therefore, is needed.

The current study was conducted to more thoroughly examine the relationship between the DRS and everyday functions. Specifically, the ability of the DRS to predict performance of everyday functions was assessed. Additionally, the relationships between individual neuropsychological measures and performance measures of everyday functioning were explored. An appropriate sample size was used.

METHOD

Subjects

Subjects were 50 patients referred for neuropsychological assessment fol- lowing their admission to the geriatric unit of a psychiatric teaching hospital. Patients were seen as part of their neurodiagnostic workup, the reason for referral frequently being to assess for the presence of a dementia. Patients with sensory or motor impairments that precluded valid assessments were not included as subjects. Also excluded were patients with severe disturbances of attention and/or orientation indicative of an acute confusional state.

Subjects ranged in age from 63-89 years (mean age = 75 years, SD = 6.4 years) and had 5 to 20 years of formal education (mean education = 10.8 years, SD = 3.2 years). The sample was predominantly female (74 percent) and right-handed (95 percent). Subjects were hospitalized for a variety of con- ditions, including depression, anxiety and probable dementia.

Measures

The DRS (Mattis, 1988) is a brief neuropsychological assessment battery designed to assess five areas of cognitive functioning in the elderly. The areas assessed include attention, initiation/perseveration (i.e., frontal systems), con- structional ability, conceptualization, and memory. The measure also yields a total score. The tasks incorporate commonly employed clinical procedures and traditional assessment methods, and include stimulus materials that are famil- iar to most individuals. The battery can be easily administered to patients in a variety of settings and it taps a range of cognitive competence, from normal levels of ability to severe impairment. The reliability and validity of the DRS have been demonstrated in healthy and neurologically impaired populations

454 J. D. Nadier et al.

(Coblentz, Mattis, Zingesser, Kasoff, Wisniewski, & Katzman, 1973; Gardner, Oliver-Munoz, Fisher, & Empting, 1981; Chase, Foster, Fedio, Brooks, Mansi, & DiChiro, 1984; Vitaliano, Breen, Albert, Russo, & Prinz, 1984).

The Occupational Therapy Evaluation of Performance and Support (OTEPS) is a standardized behavioral measure that assesses a patient’s ability to perform usual daily living tasks. The OTEPS examines everyday functioning in six areas including hygiene/self-care, safety, medication administration, cooking and nutrition, money management, and community access and utilization. Scoring within each functional domain is based on a scale of 0 to 2, where 0 indicates inability to complete the task, 1 indicates ability to do the task with assistance, and 2 indicates independent and correct completion of the task. Table 1 provides sample items for each functional domain. The instrument was developed for clinical use in the evaluation of geriatric patients. Development involved identification of areas of performance considered necessary for inde~ndent living by a group of occupational therapists at a psychiatric teaching hospital.

Interrater reliability for the OTEPS was found to be high for four of the six domains of everyday functioning, with reliability coefficients ranging from .94-.96. The remaining two domains, hygiene/self-cue and co~unity utilization, produced moderate correlations, with coefficients of .79 and .62, respectively. Test-retest reliability was not examined as this would be irrele- vant for this population of elderly patients referred in many cases to assess for the presence of dementia. In such dementing populations, one would expect changes across performances to occur as a result of the patient’s declining functional status.

The instrument’s construct validity was demonstrated through significant correlations with the Katz, a widely used index of ADL (Katz, Downs, Cash, & Gratz, 1970). Ratings on the Katz range from one, indicating the highest degree of independent living, to seven, indicating the greatest level of depen- dence. Significant correlation coefficients of -.32 to -80 were obtained between the Katz index and each of the domains of the OTEPS. Thus, patients who were more inde~ndent in their ADLs obtained higher scores in each of

TABLE 1 Content of the occUpationa Therapy Evabath of Performance and Support

(OTEPS)

ADL Domain Number of Tasks Sample Items

Hygiene Safety Medication cooking Money ~agement Community

utilizatiorl

5 AbIe to dress self 12 Identifies emergency telephone numbers 11 Identifies dosage on bottle 7 Makes a cheese sandwich

10 Writes and records a check 2 Makes informational telephone call


the OTEPS domains and received lower (more independent) ratings on the Katz index.

Adequate criterion-related validity was also shown. The OTEPS was able to accurately classify 75% of patients who were judged to be cognitively intact vs. impaired on the basis of the MMSE (Folstein et al., 1975). In addition, the OTEPS was able to accurately predict posthospital living situation with 76% accuracy.

Procedure

Subjects were administered the DRS as part of a comprehensive neuropsychological assessment conducted by a doctoral level neuropsycholo- gist. The OTEPS was administered by licensed and certified occupational therapists. Both assessment instruments were given during the patient’s inpatient hospitalization.

To determine the ability of the DRS to predict functioning in everyday skills, six linear regression analyses were conducted with the DRS total score as the predictor for each of the six functional domains measured by the OTEPS as cri- teria. Six additional standard multiple regression analyses were conducted with each of the OTEPS functional domains as criterion measures and the five DRS subscales as predictors. Finally, Pearson correlations among each of the five DRS subscales and the six OTEPS domains of everyday functioning were computed so that individual relationships could be examined. For each analysis, Bonferroni corrections were used to guard against Type 1 errors from occurring.

RESULTS

The means and standard deviations for the DRS and the OTEPS perfor-

mances are presented in Table 2. The results of the initial linear regression analyses revealed significant pre-

dictive relationships between the DRS total score and live of the six OTEPS functional domains (p < .Ol). DRS total score significantly predicted all of the everyday functional abilities, except cooking. The correlation coefficients ranged from 52 for money management to 64 for medication administration, accounting for 27% to 41% of the variance. Results of these linear regression analyses are presented in Table 3.

Standard multiple regression analyses using the DRS subtests as the predictors produced similar results. As with the DRS total score, all of the OTEPS functional domains were significantly predicted, except for cooking. The significant multiple correlations ranged from 57 for hygiene/self-care to .70 for safety, accounting for 32% to 49% of the variances. Examination of individual weight- ings among DRS subscales revealed a significant contribution at the p < .05 level for Initiation/Perseveration subtest in the prediction of all functional

456 J. D. hailer et al.

TABLE 2 Mean Scores of Patients on DRS and OTEPS

MeaSUre M SD

Dementia Rating Scale Total score Attention I~~tio~r~v~tion Construction Abstracuon M@J=Y

OEPS Activities of Daily Living Hygiene Safety M&cation Cooking M=Y ~~unity unction

121.5 17.4 34.9 2.8 29.7 6.3

5.2 1.3 31.9 5.7 19.9 5.4

9.2 1.4 18.0 6.4 13.1 8.5 6.4 6.0

10.7 7.8 2.8 1.5

domains, with the exception of hygiene, for which no individual subtest was significant. Results of these multiple regression analyses are presented in Table 4.

Computation of individual correlations revealed significant linear relationships between the DRS rnitiation/Perseveration subtest and each of the OTEPS functional domains except cooking. The DRS Memory subtest was significantly correlated with each functional domain except cooking and money management. Other DRS subtests (Construction, Abstraction, and Attentions were not signi~cantly correlated with any functional domains. Pearson correlations are presented in Table 5.

DISCUSSION

The findings reveal signi~cant predictive relationships for everyday ftmc- tioning using the DRS. Such relationships were seen for most OTEPS func-

TARLE 3 Results of Linear Regression Analyses Predicting ADL

Domsins Using DRS Total Score

Measure r rz F

Hygiene .53 .28 19.19* safety .63 .39 31.43* Mediation 64 .41 33.02* Cooking .32 .I0 5.56 Money .52 .27 17.73* Chain utilbation .61 .37 28.16*


TABLE 4 Results of Standard Multiple Regression Analysis

Predicting ADL Domains Using DRS Subtests

MeZ.ul.e R R2 F

Hygiene Sl .32 4.16* Safety .70 .49 8.54* Mediatioll .68 .47 7.x* Cooking A2 .17 1.85 Money .58 .33 4.34* Community utilization 64 .41 5.89*

*p < .Ol.

tional domains (all but cooking) when either the DRS total score was used as the predictor or when individual DRS subtests were combined as predictors. The lack of significance for the cooking variable may be related to the rela- tively automatic nature of the cooking tasks, as well as the extensive prompt- ing and assistance that is inherent in the inpatient cooking evaluation (e.g., placement in a kitchen, provision of supplies). Although the self- care/hygiene activities would also be considered automatic in nature, the method of assessment was different from the cooking tasks in that hygiene was based on naturalistic observations of whether patients initiate and engage in personal grooming behaviors (e.g., showering). Thus, those patients with significant “frontal” systems dysfunction would be expected to fail both the automatic tasks of cooking and grooming if structure and exter- nal organization were not provided.

The significant predictive relationships obtained for everyday functions were all within the moderate range of correlations. These results are fairly consistent with other studies examining predictive relationships between neuropsychological procedures and measures of everyday functioning in the elderly (Dunn et al., 1990; McCue et al., 1990). The coefficients obtained in the

TABLE 5 Pearson Correlations Between DRS and ADL Variables Witb Bonferroni

Probabilities

Measure Atm IiP

Hygiene .39 .50* Safety .33 .68** Medication .39 .61** Cooking -23 .39 Money .31 .55** Community utiliition .31 .61**

*p < .002 (= .05/30; per Bonfenoni). **p < .0005 (= .01/80; per Bonferroni).

Const Cone Mem

.36 .31 .48*

.35 .41 .53*

.38 .40 .52*

.16 .14 .26

.26 .31 .44

.39 .39 .51*


current study are similar to those demonstrated in the Dunn et al. (1990) study. This finding suggests that the relative brevity of the DRS, in comparison to the more lengthy HRNB does not result in decreased predictive ability. In fact, low subject to variable ratio seen in the Dunn et al. study may have artificially inflated correlation coefficients. This would suggest that the DRS may be a more valid and reliable predictor of everyday functioning than the HRNB.

Comparison of the current findings to McCue et al. (1990) is more difficult. Whereas the current study demonstrated larger correlations between the DRS and measures of everyday living than did the McCue et al. (1990) study using the LNNB-S, measures of everyday functioning were examined in different ways. The McCue et al. (1990) study used a functional measure that classified everyday functions according to the nature of the tasks (e.g., physically oriented instrumental self-care vs. cognitively oriented instrumental self-care). Their study did not separate individual functional domains (e.g., money management) and consequently, the analyses demonstrated relationships between the neuropsychological measures and the categories of everyday functions, rather than to the individual domains themselves. Although the method of classification is conceptually appealing and makes it possible to examine the differen- tial relationships between activities that incorporate different functional components (e.g., movement of an object vs. verbalization of information), the process of combining diverse activities into a single category may result in a loss of information about the individual activities. For example, sewing on a button and verbalizing an appropriate response to a hazardous situation are both within the classification of “cognitively oriented instrumental self-care,” yet these activities would not necessarily require the same functional or cognitive capabilities. In addition, the categories created were apparently based on presumed similarities among activities rather than empirical relationships. Such methods are vulnerable to “illusory correlation” or beliefs in relationships that appear to be, but are not valid (Wedding & Faust, 1989). They can result in interpretive errors regarding the meaning of obtained relationships. A final difference between McCue et al. (1990) and the current investigation is that the former study utilized a stepwise regression procedure for data analysis. Although this was an appropriate procedure given the large number of neuropsychological variables used (i.e., all of the LNNB-S subtests), it result- ed in many of the predictions being based on one or two subtests of the battery (e.g., memory). This consequence makes their findings difficult to interpret .

Regarding the individual subtests of the DRS, the significant contribution of Initiation/Perseveration (executive functioning) in predicting everyday functions is consistent with theoretical expectations, which suggest that these “executive” (or frontal lobe) functions are necessary for the planning, organiz- ing, and initiation of functional activities. The frontal lobes (specifically the dorsolateral areas) are involved in the initiation and execution of complex behaviors, as well as self-regulation and monitoring of performance (Stuss & Benson, 1986). Thus, it would be expected that performance of everyday func-


tions would be highly dependent on intact functioning in these areas. As previ- ously suggested, the lack of a relationship between the Initiation/Perseveration subtest and cooking may be related to the automatic nature of the task, as well as the environmental structure provided in the assessment of the task. Each of these aspects would lessen the need for “executive” (frontal lobe) input or mediation in performance.

The association of the DRS memory subtest to everyday functioning was also an expected finding, although the pattern of relationships is somewhat surprising. It was presumed that the highly routinized (procedural) functions, such as self-care, would be less related to memory (as measured by the neuropsychological instrument), whereas less frequent or less automatic activities, such as balancing a checkbook or responding to safety hazards, would place more of a demand on memory functions. This was not the case, and indicates the necessity of teasing apart the functional components of the everyday activities. For the cooking task, it may be that the “environmental cues” within the administration lessened the demand on memory for performance. Regarding the money management variable, it may be that intact computational skills, independent of memory ability, are sufficient for money management. Such speculations, however, are clearly in need of empirical confirmation.

The results support the ability of the DRS to predict an elderly patient’s performance of everyday functions in the hospital setting. Functions predicted included basic self-care, responses to safety situations, money management, medication administration, and ability to utilize community resources. The particular functional components within each activity (e.g., visual-motor inte- gration in making a telephone call), and their relationship to the cognitive domains assessed, require further study.

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The ability of the Dementia Rating Scale to predict everyday functioning