MMPI-2 indices of psychological disturbance and attention and memory test performance in head injury

Archives of Clinical Neuropsychology 18 (2003) 905–916 MMPI-2 indices of psychological disturbance and attention and memory test performance in head injury Scott R. Ross a,∗ , Steven H. Putnam b , Carlton S. Gass c , Dan E. Bailey a , Kenneth M. Adams d a Department of Psychology, DePauw University, 7 Larabee Street, Greencastle, IN 46135, USA b Wayne State University Medical Center, Detroit, MI, USA c Miami Veterans Administration Medical Center, Miami, FL, USA d University of Michigan Medical Center, Ann Arbor, MI, USA Accepted 26 July 2002 Abstract A number of studies have investigated the relationship between psychological disturbance and neuropsychological (NP) test performance. The current study is a replication and extension of Gass (1996) who found that MMPI-2 indices of psychological disturbance are related to performance on NP tests of attention and memory in psychiatric and head-injured patients. In a large sample (N = 381) referred for evaluation after sustaining presumed head injury, we examined the relationship between MMPI-2 indices of psychological disturbance and measures of attention and memory from the Wechsler Memory Scale-Revised (WMS-R; Wechsler, 1987), Wechsler Adult Intelligence Scale-Revised (WAIS-R; Wechsler, 1981), California Verbal Learning Test (CVLT; Delis, Kramer, Kaplan, & Ober, 1987), and the Memory Assessment Scales (MAS; Williams, 1991). Although related to other domains, MMPI-2 variables were most consistently related to measures of attention and List Learning. Even when demographic variables, injury severity, and litigation status were controlled, MMPI-2 indices significantly predicted performance on six out of eight tests. However, the correspondence between similar indices on the WMS-R and MAS were relatively low, especially for Verbal Memory and Visual Reproduction. Further, litigation was significant in predicting only 2 of 8 attention and memory indices. © 2002 National Academy of Neuropsychology. Published by Elsevier Ltd. All rights reserved. Keywords: MMPI-2; Litigation; Head injury; Attention; Memory ∗ Corresponding author. Tel.: +1-765-658-4576; fax: +1-765-658-4572. E-mail address: (S.R. Ross). 0887-6177/$ – see front matter © 2002 National Academy of Neuropsychology. PII: S 0 8 8 7 - 6 1 7 7 ( 0 2 ) 0 0 1 6 9 - 5 906 S.R. Ross et al. / Archives of Clinical Neuropsychology 18 (2003) 905–916 1. Introduction Investigators are increasingly interested in the relationship between psychopathology, personality and neuropsychological (NP) test performance (Burt, Zembar, & Niderehe, 1995; Gass, Ansley, & Boyette, 1994; Putnam, Millis, & Adams, 1996; Putzke et al., 1997; Wrobel & Wrobel, 1997). Recently, Gass and colleagues (1994, 1996) reported that NP measures of attention, memory, and flexibility are negatively related to psychological disturbance as measured by the MMPI-2. Content scales of Fears and Bizarre Mentation, which reflect anxiety, fear, and cognitive disturbance, were especially predictive of performance on NP tests measuring attention and memory. Gass (1996) found that measures of attention were most strongly related to psychological distress and dysfunction. In his study, the head-injured sample included a high proportion of persons with mild head injury (MHI). These findings are in keeping with the hypothesis that decreased performance on certain NP tests may be partially a function of personality disturbance in head-injured patients. 1.1. Attentional disturbance in MHI NP assessment continues to be the primary means of determining the extent of functional impairment resulting from brain damage following MHI (Putnam et al., 1996). However, a recent meta-analysis by Binder, Rohling, and Larabee (1997) suggests that this may be a difficult task. Based on studies incorporating representative samples of MHI, Binder et al.’s (1997) results indicate that the overall effect size of cognitive impairment among MHI patients is small (d = 0.12) to nonsignificant (g = 0.07). When specific NP domains were considered separately, the effect size of impairment was likewise small (d = 0.20) and significant only for measures of attention. A small effect size suggests that the base-rate of impairment in the population is low which may compromise the overall classificatory accuracy of NP tests in the identification of impairment after MHI. 1.2. Litigation status When these results are compared with those of an earlier investigation by Binder and Rohling (1996), the relationship of financial incentive to symptoms and impairment after head injury appears comparatively larger (effect size = 0.47). Nonetheless, litigation appears to produce mixed findings in studies of head injury. Youngjohn, Davis, and Wolf (1997) have reported significantly higher MMPI-2 elevations for persons in litigation as compared with nonlitigating head injury. However, performance on NP tests has been variably reported to be related to litigation status. For example, Suhr, Tranel, Wefel, and Barrash (1997) found no significant effect of litigation status on memory test scores as measured by the Rey Auditory Verbal Learning Test. Leininger, Gramling, Farrell, Kreutzer, and Peck (1990) also reported no significant effects for litigation on NP test performance. Nonetheless, many studies confound litigation status, malingering, and head injury severity when examining their relationships to NP test performance (Suhr et al., 1997). S.R. Ross et al. / Archives of Clinical Neuropsychology 18 (2003) 905–916 907 1.3. Psychological disturbance in head injury Binder (1986) also reported that persons who typically sustain the mildest head injuries are those that complain most of head injury-related symptoms. Studies using the MMPI-2 to measure psychological disturbance have also found that persons with persisting MHI, compared to those with moderate to severe head injury, have significantly higher elevations on many scales which measure self-reported psychological disturbance (Berry et al., 1995; Leininger, Kreutzer, & Hill, 1991; Youngjohn et al., 1997). Binder et al.’s (1997) results lead Binder (1997) to conclude that “there is little empirical evidence that prolonged NP deficits typically are caused by mild head trauma (MHT)” (p. 448, emphasis added). If decreased performance on NP tests is sometimes driven by nonneurologic factors as Binder (1997) suggests, then it is important to determine to what extent such factors, including psychological disturbance, may be related to NP tests often employed as putative measures of brain-behavior status (see Reitan & Wolfson, 1997, for a review). 1.4. Current study hypotheses The current study is a replication and extension of Gass’ (1996) investigation of the relationship between MMPI-2 indices of psychological disturbance and test performance on measures of attention and memory in head injury. As a first step in replicating Gass’ original findings, we examined patient’s scores on measures of attention and memor (...truncated)