The Clinical Neuropsychologist -//-$., Vol., No., pp. - Swets & Zeitlinger Elderly Norms for the Hopkins Verbal Learning Test-Revised* Rodney D. Vanderploeg, John A. Schinka, Tatyana Jones, Brent J. Small, Amy Borenstein Graves, and James A. Mortimer,, James A. Haley VA Medical Center, Departments of Psychology and Neurology, University of South Florida, Defense and Veterans Head Injury Program, Department of Psychiatry, University of South Florida, Department of Gerontology, University of South Florida, Department of Epidemiology and Biostatistics, University of South Florida, and Institute on Aging, University of South Florida Downloaded by [University of South Florida] at : December ABSTRACT The present study evaluates the effects of age, education, and gender in a representative sample of older adults and provides normative data for community-dwelling elderly. Age and gender had significant effects on HVLT-R performance. We provide age- and gender-adjusted normative data. Surprisingly, education level did not affect HVLT-R performance, indicating that education-adjusted norms are not necessary for this measure within this age range. We evaluated a subsample of subjects census-matched on age, education, and gender. These subjects did not differ in overall performance from our entire sample. Therefore, the normative data provided in this paper can be considered to be census-comparable for age, education, and gender. The Hopkins Verbal Learning Test (HVLT; Brandt, 99) is a brief verbal learning and memory instrument developed to enhance utility over existing memory measures. It is well suited for use with difficult-to-test or more severely impaired patients. The HVLT consists of a - item word list presented in three consecutive trials. The word list is composed of three semantic categories with four words in each. A yes/no recognition task immediately follows the three successive learning trials. The recognition task consists of words, from the recall list, distracters that are semantically related to the recall items, and unrelated words. Six equivalent forms were created to reduce practice-related measurement error for patients who undergo serial testing. The HVLT has shown evidence of utility and convergent validity with similar measures such as the CVLT (Lacritz & Cullum, 99a). In a sample of healthy older adults, Lacritz and Cullum (99a) found a correlation of. between the total number of words learned across trials for both tests. In the initial research (Brandt, 99), parallel forms of the HVLT were found to be equivalent for total learning and discrimination. Rasmusson et al. (99) found that, over a period of 9 months, HVLT performance was stable for each alternate form. Limitations of the original HVLT were its lack of delayed recall or delayed recognition trials. Benedict, Schretlen, Groninger, and * The Charlotte County Healthy Aging Study was supported by the Charlotte County Foundation and the University of South Florida Institute on Aging. Research was also supported in part by the Department of Veterans Affairs. Portions of this paper were presented at the th Annual Convention of the American Psychological Association, Washington, DC, USA, August. Address correspondence to: Rodney Vanderploeg, Psychology Service (B), James A. Haley Veterans Hospital, Bruce B. Downs Boulevard, Tampa, FL, USA. Tel: + (). Fax: + 9. E-mail: Rodney.Vanderploeg@med.va.gov. Accepted for publication: May,.
ELDERLY NORMS FOR THE HVLT-R 9 Downloaded by [University of South Florida] at : December Brandt (99) revised the HVLT to address these limitations by adding a minute delay between the learning trials and the delayed free recall and recognition trials. The authors argue that the HVLT-R still maintains its brevity and utility with difficult populations, while providing a more comprehensive assessment of memory. The six parallel forms have been shown to be equivalent for the learning trials, as well as free recall, percent retained, and recognition of true positives (Benedict & Zgaljardic, 99; Benedict et al., 99). The HVLT-R has been found to have adequate convergent validity with the CVLT across learning and recognition trials in demented patients (Lacritz & Cullum, 99b). Although the HVLT-R has promising psychometric characteristics, to date there has been only one set of norms published (Benedict et al., 99). These norms were developed from a sample with an above-average estimated IQ (IQ = ) that was quite restricted in range (Standard Deviation = 9.). The older portion of this sample consisted of well-educated (over. mean years ofeducation), community-dwellingadults, aged years. Benedict et al. (99) found a significant effect of age and education on performance, but did not evaluate the effect of gender. The purpose of the present study was to evaluate the effects of age, education, and gender in a representative sample of older adults and, based on the results of these analyses, to provide normative data for community-dwelling elderly. METHOD Participants Data for the present study were obtained from the Charlotte County Healthy Aging Study (CCHAS; Small et al., ). CCHAS is a representative, population-based, cross-sectional study of individuals, aged, living in two census tracts of Charlotte County, Florida. Information was obtained by structured interviews with participants on demographic variables, personal and family medical history, smoking and alcohol consumption, depression, anxiety, social support, work history, physical and mental exercise, and risk factors for dementia. Participants also received a battery of cognitive ability measures that included the HVLT-R. More complete information on CCHAS participant selection and data collection procedures is provided in Small et al. (). Procedures Exploratory data analyses were conducted to examine distributions of scores for the HVLT-R and to identify cases with missing or inconsistent demographic data. Data from nine participants were dropped from the data set as a result of these analyses. Cases were also excluded if they reported a history of any of the following: endarterectomy, transient ischemic attacks, cerebrovascular accidents, Parkinson s disease, or traumatic head injury with loss of consciousness and retrograde amnesia. A total of cases were dropped for meeting one or more of these criteria. Finally, participants were excluded because they were unable or unwilling to complete one or more of the neuropsychological tests in the battery. Participant data were not screened for history of psychiatric disorder. The final data set available for analysis consisted of 9 individuals: men and women. These gender proportions are generally consistent with population-based data for these age ranges. The racial composition of the sample was: 9.% Caucasian,.% African American,.% Asian American,.% Native American, and.% Other. Form of the HVLT-R was administered in the standard fashion as part of a larger battery of tests. The following indices were scored: Trial, Trial, Trial, Learning, Sum of Trials to, Delayed Recall, Delayed Cued Recall, Percent Retained, Recognition True Positives, Recognition False Positives, and Discrimination Index. The Delayed Cued Recall score is a new score not previously reported. Following delayed free recall, subjects were given memory cues and asked, one subcategory at a time, to recall all words on the list that were from the subcategories: () places to live, () four-legged animals, and () precious stones. The Learning measure is calculated as the higher of Trials or Trial recall, minus Trial recall. The Percent Retained score is the Delayed Recall score divided by the better of Trial or Trial recall, multiplied by. The Discrimination Index is calculated as the Recognition True Positives minus False Positives.
R.D. VANDERPLOEG ET AL. Downloaded by [University of South Florida] at : December RESULTS The sample s average number of years of education is higher (M =. years) than that projected for the census data in for this age range (M =. years). To evaluate the impact that this factor might have on normative distributions, a subset of cases was selected to match the projected census data (US Department of Commerce, 99). Projected census data were used, rather than census projections, to extend the usefulness of the current norms throughout the decade. The Personality Assessment Inventory (PAI; Morey, 99) used a similar strategy. Published in 99, the PAI used a standardization sample based on 99 census projections in order to provide the closest approximation to the US adult population throughout the decade (Morey, 99, p. ). To accomplish this census match, the census data were used to determine the total and proportionate number of cases required on the basis of gender and of cross-stratification by age and education. Matching participants were then randomly selected until the required total and proportionate number of cases was met. Participants were then coded as either census matches (n = ) or misses (n = 9). Table. HVLT-R Performance on Sum of Trials to by Age and Gender Categories. Total Sample Census Matched Subsample Age Gender N M (SD) N M (SD) 9 Genders Combined 9 Genders Combined Male Female Male Female Male Female Genders Combined 9 9... 9.... 9.. We used multiple linear regression to examine the effects of census match, gender, age, and education on HVLT-R scores. All of the HVLT- R measures were examined separately: Trial, Trial, and Trial, Sum of Trials to, Learning, Delayed Free Recall, Delayed Cued Recall, Percent Retained, True Positives, False Positives, and Discrimination Index. However, results were consistent across indices; therefore, only the findings from Sum of Trials to will be reported. Age, education, gender, and census match were entered simultaneously into the regression model. Table presents the results of this analysis. Age and gender contributed significant unique variance in the prediction of HVLT-R Sum of Trials to score; education and census did not. Based on this regression analysis, descriptive data for HVLT-R performance by age and gender category were calculated for the entire sample of 9 individuals, as well as for the subsample census-matched on education and gender (n = ; see Table ). An ANOVA with years of education (<,,, > ), age ( 9, 9, ), gender, and census status as independent variables, and HVLT-R Sum of Trials to performance as the dependent variable, similarly revealed significant effects for age and gender, but no interaction and no (.9) (.) (.) (.) (.9) (.) (.) (.) (.) 9 9....... 9.. (.) (.) (.9) (.9) (.) (.) (.) (.) (.) Total 9. (.9). (.)
ELDERLY NORMS FOR THE HVLT-R Table. Results of Demographic and Census Regression Analysis for Sum of Trials to. Standardized Beta t-value Significance Unique Variance Age Education Gender Census Status.9............%.%.%.% Downloaded by [University of South Florida] at : December effect for education or census. The effect sizes for age (eta squared =.) and gender (eta squared =.) were small. The HVLT-R Sum of Trials to is comparable between the 9 and 9 year age groups (Tukey s HSD: p =.). However, these two groups performed better than the year olds (Tukey s HSD: ps <.) by about. points. The standard deviations for all three age ranges are comparable. Given the comparability of the censusmatched subsample with the remainder of the sample, for norming purposes the full sample was used. This allows for a better plotting of the frequency distributions, particularly at the upper and lower ends of the distribution. For similar reasons, all age groups were combined and age adjustments, as described in Table, were provided. These adjustments can be used to determine relative performance compared to agematched peers. Women, across all age groups, consistently performed better than men (p <.) by about points. Again, for norming purposes, data from both genders were combined to plot frequency distributions, and gender adjustments were made to raw scores (as described in Table ). This frequency distribution information for each HVLT-R index can be found in Table. Table presents raw score adjustments which must be made prior to looking up level of performance information in Table, in order to obtain age- and gender-based normative levels of performance. DISCUSSION The present study provides normative data for elderly individuals aged to. Our analyses found that age and gender have a significant effect on HVLT-R performance. The performance differences associated with age were small, but those for gender differences were moderate in size. Therefore, in contrast to Benedict et al. (99), who only provided age-based norms, we provide age- and gender-adjusted normative data. Somewhat surprisingly, level of previously attained education did not affect HVLT-R performance, indicating that education-adjusted norms are not necessary for this measure. Finally, we evaluated a subsample of subjects census-matched on age, education, and gender. These subjects did not differ in overall performance from our entire sample. Therefore, the normative data provided in this paper can be considered to be census-comparable on age, education, and gender. There are several limitations to the present study. First, only Form of the HVLT-R was used. Although previous studies have demonstrated the equivalence of forms (Benedict & Zgaljardic, 99; Benedict et al., 99), it is not known whether age and gender effects would be comparable across forms. Second, because our sample was 9.% Caucasian, we were not able to determine whether racial composition played any role in HVLT-R. However, some research has shown that, once other demographic factors have been controlled, racial composition plays a minimal role in cognitive performance (Vanderploeg & Schinka, 99). Therefore, the norms provided in this paper are likely to be useful across racial groups as well. Third, the version of the HVLT-R used in this study has a cued recall trial between the delayed free recall and delayed recognition trials. The addition of this cued recall trial, although unlikely, may influence performance on the recognition measure. Therefore, recognition trial data with this ver-
R.D. VANDERPLOEG ET AL. Downloaded by [University of South Florida] at : December Table. Normative Data for HVLT-R Performance for Individuals of to Years of Age. Cumulative Percentile Levels M (SD) Range 9 9 99 Trial Trial Trial Learning Sum of Delayed Recall Cued Recall Percent Retained True Positives False Positives* Discrimination Index....... 9... 9. (.) (.) (.) (.) (.) (.) (.) (.) (.) (.) (.9) 9 9 9 9 9 9 9 9 9 9 9 9 9 * = Reverse scored (i.e., more false positives is an indication of poor performance).
ELDERLY NORMS FOR THE HVLT-R Table. Age and Gender Adjustments to HVLT-R Raw Scores to Estimate Age- and Education-Based Level of Performance. Gender HVLT-R Index Age Male Female Downloaded by [University of South Florida] at : December Trial Trial Trial Learning Sum of Delayed Recall Cued Recall Percent Retained True Positives False Positives Discrimination Index 9 9 9 9 9 9 9 9 9 9 9 Note. The values in this table can be added to or subtracted from a raw score prior to looking up level of performance information in Table. This would result in an age- and gender-adjusted score. sion of the HVLT-R may not be comparable with previously published recognition trial data. The norms provided in this study have a somewhat lower level of performance and a slightly wider distribution than those provided by Benedict et al. (99). In fact, our sample had about one standard deviation lower performance (about raw score points on sum of trials to ). This difference is most likely attributable to the finding that the norms provided by Benedict et al. (99) were on a rather homogeneous sample with an above-average estimated IQ of (SD = 9.). Given the epidemiological nature of the current sample, the comparability of performance with a census-matched subsample, and the large sample size, the normative data available here are likely to be superior to the previously published norms for the elderly.... REFERENCES... Benedict, R.H.B., Schretlen, D., Groninger, L., & Brandt, J. (99). Hopkins Verbal Leaning Test- Revised: Normative data and analysis of inter-form and test-retest reliability. The Clinical Neuropsychologist,,. Benedict, R.H.B., & Zgaljardic, D.J. (99). Practice effects during repeated administrations of memory tests with and without alternate forms. Journal of Clinical and Experimental Neuropsychology,, 9. Brandt, J. (99). The Hopkins Verbal Learning Test: Development of a new memory test with six equivalent forms. The Clinical Neuropsychologist,,. Lacritz, L.H., & Cullum, C.M. (99a). The Hopkins Verbal Learning Test and CVLT: A preliminary comparison. Archives of Clinical Neuropsychology,,. Lacritz, L.H., & Cullum, C.M. (99b). Utility of the Hopkins Verbal Learning Test-Revised in Alzheimer s disease. Paper presented at the American
R.D. VANDERPLOEG ET AL. Downloaded by [University of South Florida] at : December Psychological Association conference, San Francisco, CA. Morey, L.C. (99). Personality Assessment Inventory. Odessa, FL: Psychological Assessment Resources. Rasmusson, D., Xeno, B., Frederick, W., & Brandt, J. (99). Stability of performance on the Hopkins Verbal Learning Test. Archives of Clinical Neuropsychology,,. Small, B.J., Graves, A.B., McEvoy, C.L., Crawford, F.C., Mullan, M., & Mortimer, J.A. (). Is Apolipoprotein E a risk factor for cognitive impairment in normal aging? Evidence from a population-based sample of older adults. Neurology. US Department of Commerce, Bureau of the Census (99). Current population reports, population projections of the United States by age, sex, race, and Hispanic origin: 99 (Series P- ). Washington, DC: Government Printing Office. Vanderploeg, R.D., & Schinka, J.A. (99). Predicting WAIS-R IQ premorbid ability: Combining subtest performance and demographic variable predictors. Archives of Clinical Neuropsychology,, 9.