Brad L. Roper

Verbal Fluency: Language or Executive Function Measure?

Measures of phonemic and semantic verbal fluency, such as FAS and Animal Fluency (Benton, Hamsher, & Sivan, 1989), are often thought to be measures of executive functioning (EF). However, some studies (Henry & Crawford, 2004a, 2004b, 2004c) have noted there is also a language component to these tasks. The current exploratory factor-analytic study examined the underlying cognitive structure of verbal fluency. Participants were administered language and EF measures, including the Controlled Oral Word Association Test (FAS version), Animal Fluency, Boston Naming Test (BNT), Vocabulary (Wechsler Adult Intelligence Scale-III), Wisconsin Card-Sorting Test (WCST, perseverative responses), and Trail-Making Test-Part B (TMT-B). A 2-factor solution was found with the 1st factor, language, having significant loadings for BNT and Vocabulary, while the second factor was labeled EF because of significant loading from the WCST and TMT-B. Surprisingly, FAS and Animal Fluency loaded exclusively on to the language factor and not EF. The current results do not exclude EF as a determinant of verbal fluency, but they do suggest that language processing is the critical component for this task, even without significant aphasic symptoms. Thus, the results indicated that both letter (phonemic) and category (semantic) fluency are related to language, but the relationship to EF is not supported by the results.

Expansion and Re-examination of Digit Span Effort Indices on the WAIS-IV

The Digit Span subtest was significantly revised for the WAIS-IV as an ordinal sequencing trial was added to increase working memory demands. The present investigation sought to validate an expanded version of Reliable Digit Span (RDS-R) as well as age-corrected scaled score (ACSS) from the recently revised Digit Span. Archival data were collected from 259 veterans completing the WAIS-IV Digit Span subtest and Word Memory Test (WMT). Veterans failing the WMT performed significantly worse (p < .001) on the ACSS, RDS-R, and traditional RDS. Operational characteristics of the ACSS, RDS-R, and RDS were essentially equivalent; however, sensitivity was quite modest when selecting cutoffs with strong specificity. While current results suggest that Digit Span effort indices can contribute to the detection of suboptimal effort, additional symptom validity indicators should be employed to compensate for limited sensitivity.

Use of the odds ratio to translate neuropsychological test scores into real-world outcomes: from statistical significance to clinical significance.

Standard parametric tests generate p values and effect sizes, but often these are difficult to translate into real-world outcomes. In this study, the odds ratio was applied to neuropsychological testing and was compared to parametric approaches. Participants were 26 community-dwelling adults with possible or probable Alzheimers disease and 25 matched healthy community-dwelling volunteers. Odds ratios were computed to estimate the probability of concurrent diagnosis given neuropsychological performance level. Odds ratios discriminated the groups at magnitudes that could not be discerned from t-test significance tables. These values were compared to sensitivity, specificity, and overall accuracy. Clinical and research applications and implications were addressed.

Validity testing and neuropsychology practice in the VA healthcare system: results from recent practitioner survey*

Abstract Objective: A survey of neuropsychologists in the Veterans Health Administration examined symptom/performance validity test (SPVT) practices and estimated base rates for patient response bias. Method: Invitations were emailed to 387 psychologists employed within the Veterans Affairs (VA), identified as likely practicing neuropsychologists, resulting in 172 respondents (44.4% response rate). Practice areas varied, with 72% at least partially practicing in general neuropsychology clinics and 43% conducting VA disability exams. Results: Mean estimated failure rates were 23.0% for clinical outpatient, 12.9% for inpatient, and 39.4% for disability exams. Failure rates were the highest for mTBI and PTSD referrals. Failure rates were positively correlated with the number of cases seen and frequency and number of SPVT use. Respondents disagreed regarding whether one (45%) or two (47%) failures are required to establish patient response bias, with those administering more measures employing the more stringent criterion. Frequency of the use of specific SPVTs is reported. Conclusions: Base rate estimates for SPVT failure in VA disability exams are comparable to those in other medicolegal settings. However, failure in routine clinical exams is much higher in the VA than in other settings, possibly reflecting the hybrid nature of the VA’s role in both healthcare and disability determination. Generally speaking, VA neuropsychologists use SPVTs frequently and eschew pejorative terms to describe their failure. Practitioners who require only one SPVT failure to establish response bias may overclassify patients. Those who use few or no SPVTs may fail to identify response bias. Additional clinical and theoretical implications are discussed.

Limited Accuracy of Premorbid Intelligence Estimators: A Demonstration of Regression to the Mean

Regression-based premorbid intelligence estimators have been devised by Barona, Reynolds, and Chastain (1984), Barona and Chastain (1986), Hamsher (1984), Krull, Scott, and Sherer (1995; the Oklahoma Premorbid Intelligence Estimate: OPIE), and Vanderploeg, Schinka, and Axelrod (1996; BEST-3 approach), but little is known of their relative accuracy, particularly in outer ranges of intellectual ability (e.g., below-average, superior, etc.). Towards this end, the Wechsler Adult Intelligence Scale-Revised (WAIS-R) was administered to 150 neurologically normal adults, and estimated VIQ, PIQ, and FSIQ scores were computed according to each regression method. Results showed that methods based solely on demographic factors were most susceptible to meanward regression, rendering them poor estimators of IQ scores in outer ranges. Although the OPIE and BEST-3 performed somewhat better, their accuracy remained relatively weak. The findings suggest that regression-based estimates of premorbid IQ are very susceptible to error, particularly in outer ranges of intellectual function.

Language-based embedded performance validity measures in traumatic brain injury

No studies to date have investigated the Boston Naming Test (BNT) as an embedded performance validity test (PVT). This study investigated the classification accuracy of the Boston Naming Test (BNT) and the Verbal Fluency Test (FAS and Animal Fluency), as embedded PVTs in a compensation-seeking mild traumatic brain injury (MTBI) sample (N = 57) compared to a non-compensation-seeking moderate-to-severe TBI (STBI) sample (N = 61). Participants in the MTBI sample who failed two or more PVTs were included, as were STBI participants who passed all PVTs. The classification accuracy of the individual tests and a logistically derived combined (LANGPVT) measure were studied. Results showed significant group differences (p < .05) on BNT, Animal Fluency, and LANGPVT between the MTBI and STBI groups. However, receiver operating characteristic (ROC) analyses indicated that only LANGPVT had acceptable classification accuracy (area under the curve > .70). Setting specificity at approximately .90, the recommended LANGPVT cutoff scores had sensitivity of .26. Results indicated that, similar to other embedded PVTs, these measures had low sensitivity when adequate specificity levels were maintained. However, extremely low scores on these measures are unlikely to occur in non-compensation-seeking, non-language-impaired, STBI cases.

Validation of the Repeatable Battery for the Assessment of Neuropsychological Status - Effort Index in a Veteran Sample

The RBANS Effort Index (RBANS-EI; Silverberg, Wertheimer, & Fichtenberg, 2007) is an embedded measure of effort within a frequently employed neuropsychological screening battery. While it has been criticized for inadequate specificity in older non-litigating samples (Hook, Marquine, & Hoelzle, 2009; Warren et al., 2010), the RBANS-EI has yet to be investigated in a non-geriatric veteran sample. Archival data were collected from 85 veterans who completed the RBANS and WMT within either a routine neuropsychological evaluation (n = 66) or compensation evaluation (n = 19). At a cutoff of >3 RBANS-EI exhibited strong specificity (.94) yet limited sensitivity (.31) in the prediction of WMT performance. Examination of RBANS-EI component subtests found that List Recognition <17 had strong specificity (.90) and moderate sensitivity (.52) in discriminating WMT performance groups. In contrast, Digit Span performance was comparable between those passing and failing the WMT. Present findings indicate that both the RBANS-EI and List Recognition subtest may be useful in detecting suboptimal effort yet raise questions regarding the Digit Span component of the RBANS-EI.

PPVT-R as an estimate of premorbid intelligence in older adults.

The Peabody Picture Vocabulary Test-Revised (PPVT-R) was examined as an estimate of premorbid intelligence in a clinical sample of elderly patients (N = 150) undergoing clinical neuropsychological evaluation. PPVT-R standard scores were compared across grossly cognitively intact, mildly/moderately and severely impaired groups of patients, and compared to a short form of the Wechsler Adult Intelligence Scale-Revised (WAIS-R) and the Barona regression equation. Results indicate that, while the PPVT-R is vulnerable to increasing levels of cognitive impairment among patients with fewer years of education, the PPVT-R is stable across mild to moderate levels of impairment for patients with greater than 12 years of education. In a sub-sample of grossly cognitively intact patients (n = 91), the PPVT-R standard score correlated significantly with estimated WAIS-R FSIQ (r = .61). Compared to the Barona equation, the PPVT-R was less likely to over-estimate WAIS-R FSIQ in the grossly cognitively intact patients. These data suggest the PPVT-R to be a useful estimate of premorbid ability for patients with a greater than high-school education.

Staying on the job: The relationship between work performance and cognition in individuals diagnosed with multiple sclerosis

People with multiple sclerosis (MS) are apt to become unemployed as the disease progresses, and most research implies that this is due to diminishing mobility. Some studies have shown that presence of cognitive impairment also predicts employment status. Yet, no studies have examined how neuropsychological factors predict vocational performance among individuals with MS who remain employed. We assessed employer- and self-rated work performance, mobility status, and neuropsychological function in a sample of 44 individuals diagnosed with MS. Results suggest that cognitive impairment is common in these employed individuals, despite largely intact mobility status. Moreover, a significant interaction emerged, such that cognitively impaired individuals’ work performance was rated more poorly by supervisors. In contrast, self-ratings of work performance were higher in cognitively impaired than in unimpaired participants. These novel findings suggest that cognitive impairment may influence work performance, even in patients whose physical disability status is relatively intact.

Older Adult Norms for the Southern California Figure-Ground Visual Perception Test

Older adult norms for men are provided for the Southern California Figure-Ground Visual Perception Test (FG; Ayres, 1966), based on the performance of 117 patients from a geriatric medicine and rehabilitation facility ranging in age from 40 to 77 years. Reasons are presented for administering the entire test rather than using the traditional cutoff. When comparing FG performance to norms of younger adults (Bieliauskas, Newberry, Gerstenberger, 1988), results indicate that figure-ground discrimination is poorer in older individuals. The norms provided here serve to complement the previous study employing FG, and it is hoped that they will encourage its wider use.