Introduction

.

Discussion

Methods

Results

Nisha Patel, Deirdre McGovern, Claudia Drossel, Ph. D, Nicolette Gabel, Ph. D

University of Michigan

Traumatic brain injury (TBI) and other neurological conditions are

associated with a range of cognitive impairments depending on the

severity and location of injury. Verbal fluency (VF) tasks, standard

components of most neuropsychological batteries, may be

associated with multiple cognitive domains such as language,

processing speed, memory, and executive functioning1. Pattern of

performances associated with VF may differ by neurological

conditions. We therefore explored the relationships between VF

and other associated cognitive domains in different groups of

patients routinely referred for neuropsychological assessment,

specifically, TBI vs. other neurological conditions (e.g., stroke,

epilepsy, multiple sclerosis).

Participants: 280 outpatients of a Neurorehabilitation Clinic. All

participants were administered a standard battery of tests for the

purpose of clinical care. Of this pool, seven were then excluded for

poor performance on a test of engagement. The number of participants

included in the final analyses was therefore 273 (TBI n= 181;

Other n= 92).

Measures: All scores reported as Standard Scores (mean = 100, SD = 15)

• Controlled Oral Word Association Test (FAS): A timed test of verbal

fluency requiring rapid word generation to a phonemic cue (i.e., “give

me words that begin with this letter”)

• Booklet Category Test (BCT): A test of executive functioning requiring

deductive reasoning

• WAIS-IV Processing Speed Index (PSI): tests of grapho-motor speed,

such as digit-symbol substitution and visual matching/searching

• WAIS-IV Verbal Comprehension Index (VCI): tests of vocabulary,

semantic reasoning, and verbal knowledge

• California Verbal Learning Test-Long Delay Free Recall (CVLT):

Delayed recall of a word list learned over 5 trials

• Peabody Picture Vocabulary Test-IV (PPVT): A test of receptive

vocabulary requiring participants to match a pictures to words.

Our results demonstrate that VF is related to several domains of

cognitive functioning. The contribution of each of these

additional cognitive domains to VF performance subtly differs

in individuals with TBI compared to other neurological

conditions, such that in the TBI group, both processing speed

and overall verbal abilities were found to contribute

significantly to phonemic VF above and beyond the other

cognitive domains assessed. In non-TBI neurological

conditions, only general verbal abilities contributed uniquely to

variance in VF. Findings indicate that assessing phonemic VF

performance in TBI can inform clinicians about processing

speed in addition to verbal abilities, and that clinical syndromes

should be carefully considered when interpreting performances

on tests of VF. Finally, rehabilitation treatment

recommendations based on poor VF performance should

include both language-focused treatment and processing speed

interventions for patients with TBI.

Verbal Fluency Performance: Clinical Syndrome Matters

Results (continued)

ANOVA revealed a significant difference in FAS score between the

TBI group and Non-TBI group (F(1, 264) = 4.8, p<0.05; see

Figure 1).

Figure 1.

Average scores on Neuropsychological Assessments by Group

(Standard score mean = 100, SD = 15)

Correlational analyses demonstrated that all variables were

significantly related (see Table 1).

Table 1.

Correlations Among Neuropsychological Scores

9587 89

9585

10088

81 85

97

82

98

0

20

40

60

80

100

120

FAS BCT PSI VCI CVLT PPVT

Sta

nd

ard

Sco

re

TBI

Other

*

*Mean difference significant at p < 0.05

1.Pekkala, S. (2012). Verbal Fluency Tasks and the Neuropsychology of Language. In M. Faust (Ed.) The Handbook of the Neuropsychology of Language (pp. 619-634). West Sussex, UK: John Wiley and Sons, Ltd. Retrieved from http://onlinelibrary.wiley.com/doi/10.1002/9781118432501.ch30/pdf

BCT PSI VCI CVLT PPVT

FAS .240** .427** .436** .284** .304**

BCT .367** .239** .215** .276**

PSI .473** .498** .431**

VCI .437** .803**

CVLT .357**

**p < 0.01

TBI Other Neurological Conditions

Variable β95% Confidence

Intervalβ

95% Confidence

Interval

Constant [-7.62, 3.04] [-10.43,3.62]

BCT 0.10 [-.02,0.07] 0.06 [-0.05,0.08]

PSI 0.34** [0.02,0.12] 0.26 [-0.01,0.11]

VCI 0.35* [0.1,0.14] 0.55* [0.02,0.20]

CVLT -0.07 [-0.64,0.30] -0.03 [-0.80,0.65]

PPVT -0.17 [-0.11,0.03] -0.24 [-0.14,0.04]

R2 0.23 0.29

F 6.04 4.24

*p < 0.05, **p < 0.01

Hierarchical regression analyses demonstrated differences in the

contribution of these variables to VF performance for patients

with TBI vs. Other neurological conditions. See Table 2.

Table 2.

Hierarchical Regression Models for TBI vs. Other Neurological

Conditions