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Measuring personality and emotional functioning in multiple sclerosis: a cautionary note
Archives of Clinical Neuropsychology 18 (2003) 419–429
Measuring personality and emotional functioning in multiple sclerosis: a cautionary note Linda D. Nelson a,∗ , Joseph T. Elder b , Pany Tehrani a , Jantje Groot a a
Neurology Department, University of California, Irvine, Medical Center, 101 The City Drive, Route 81, Building 53, Room 225, Orange, CA 92868, USA b Atlanta Veteran Affairs Medical Center/Emory University School of Medicine, Atlanta, GA 30322, USA Accepted 25 April 2002
Abstract Changes in personality and emotional status are common in individuals with multiple sclerosis (MS). The purpose of this study was to examine results based on the MMPI-2 before and following application of a statistical correction procedure (Gass, 1992). This was done to help determine changes in scale score elevations when items containing actual physical symptoms are identified and statistically removed. Twenty-eight participants with MS were administered the MMPI-2, then retested 1 year later. Stability of MMPI-2 scores over time was demonstrated. Results showed that when the correction procedure was applied to the MMPI-2, eight standard clinical scale scores dropped an average of 6.66 T-score points. Significant differences were obtained between standard MMPI-2 scored profiles and corrected profiles on Scales 1–3 and 8. Cautious interpretation of MMPI-2 results for neurological samples was indicated. This study extended prototypic research by using patients with MS, examining the stability of results over time (1 year), and introducing a more reliable method of deriving standard T-scores in the correction procedure. © 2002 National Academy of Neuropsychology. Published by Elsevier Science Ltd. All rights reserved. Keywords: MMPI-2; Multiple sclerosis; Assessment; Emotional functioning; Personality; Neurological
Changes in personality and emotional functioning are common in multiple sclerosis (MS) (Beatty, 1993; Minden & Schieffer, 1990; Rodgers & Bland, 1996; Schiffer & Caine, 1991). These emotional changes pose a major challenge to patients, many of whom are also struggling with the concomitant and debilitating physical effects of their disease (Knight, Devereux, & Godfrey, 1997). Reliable assessment of secondary emotional problems is key to diagnosis ∗
Corresponding author. Tel.: +1-714-456-8311; fax: +1-714-456-8805. E-mail address: [email protected] (L.D. Nelson).
0887-6177/02/$ – see front matter © 2002 National Academy of Neuropsychology. PII: S 0 8 8 7 - 6 1 7 7 ( 0 2 ) 0 0 1 5 8 - 0
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and treatment planning. Unfortunately, reliable assessment of emotional functioning in neurological samples is not always possible using standard test methods. Normative standards for many of the available personality tests are based on the general population. Patients with neurological complaints are compared against these normative groups and not surprisingly are found to score significantly different. Many of these personality tests are self-reported and, while well-suited to the general population, may not be appropriate when special populations are considered. Personality test items that reflect physical and cognitive symptoms of central nervous system (CNS) diseases are administered to, and typically endorsed by people with CNS conditions. These items have face-value neurological content, including references to motor weakness, paresis, imbalance, incoordination, dysarthria, numbness, paresthesia, visual difficulties, tinnitus, and difficulties with concentration and memory. While many of these test items represent typical complaints of patients with MS, individuals with a primary psychiatric disturbance may express similar complaints, but for different reasons. Consequently, individuals with neurological problems inadvertently inflate scores from scales designed to measure symptoms of neurotic and psychotic conditions (Reitan & Wolfson, 1993). Endorsement of physical symptoms may increase scores from scales that were originally designed to measure psychopathology (Nyenhuis et al., 1995). Thus, elevated levels of emotional functioning based on the MMPI appear when none are in fact present. People who suffer from MS are faced with a serious disease of often unremitting and unpredictable proportions. Symptoms of MS can severely impair daily functioning and, at their worst, leave individuals wheelchair bound, blind, or incapable of caring for themselves. This chronic disease of the CNS is characterized by demyelination of axons, which delay or block transmission of nerve impulses (Hallpike, Adams, & Tourtellote, 1983). Medical features of the disease include a variety of physical symptoms, such as dizziness, fatigue, bladder problems, and loss of coordination (Hallpike et al., 1983). The age of onset is typically in the early twenties. Numerous investigators suspect that neurological content bias in the MMPI is particularly problematic when patients with MS are evaluated. Indeed, a number of “MS-related” test items have been identified on the MMPI (Baldwin, 1952; Elder, 1999; Marsh, Hirsch, & Leung, 1982; Meyerink, Reitan, & Selfz, 1988; Mueller & Girace, 1988). Thus, a test designed to measure personality and emotional functioning instead yields type and levels of impaired mental and physical functioning. The question of whether or not the individual is suffering from emotional problems, psychosomatic complaints, or true physical symptoms of the disease remains unanswered using the MMPI-2. The danger comes in false positive interpretations of emotional difficulties, instead of true expressions of a neurological state. Over 10 years ago, a review of the literature by Minden and Schieffer (1990) recommended that clinicians “use appropriate statistical analyses to determine whether somatic symptoms are biasing the results [of self-report inventories in neurological samples] (p. 103).” In the past 10 years, a number of studies were designed to determine what constituted “appropriate statistical analyses.” A relatively stringent three-stage empirical approach emerged, in which CNS-related items from the MMPI and MMPI-2 were identified (Edwards, Weissman, & Morrison, 1993; Gass, 1992; Gass, 1996). Item content purportedly measured common effects of focal brain lesions, such as motor and sensory impairments. The effects of statistically
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removing these test items on overall performance were determined. Results supported that personality test interpretations should include both the standard scoring method (as recommended in the test manual), as well as a method involving item removal and test rescoring. Gass and others advocated that clinicians apply each method when scoring the MMPI-2 to improve reliability of results for neurological patients. This study addressed the impact of endorsing specific MMPI-2 items. It was designed with the above considerations in mind, allowing for a neurological correction procedure developed and applied to the MMPI-2. Individuals with MS were selected for study because it is a neurological disease characterized by a high incidence of physical and mental complaints. As this study will demonstrate, apparent high levels of emotional problems will be identified that are more a physical manifestation of a neurological disease, than an actual emotional condition. This study extends prototypic research by using patients with MS, by examining stability of results over time (1 year) and by introducing a more reliable method of deriving standard T-scores to the correction procedure.
1. Method 1.1. Sample Participants were 28 individuals diagnosed with clinically definite MS by treating physicians who were selected from a larger MS study (Elder, 1999; N = 70). Mean time from date of diagnosis to date of initial testing was 11.22 (S.D. = 8.55) years. In the present study, 13 participants had a chronic-progressive course and 14 were relapsing-remitting at initial testing and retest. A chronic-progressive course is typically a continuous manifestation of symptoms. Relapsing-remitting pertains to a course in which symptoms remit for a period of time, then re-occur anywhere from months to years later. In one case, course was uncertain. When groups were compared by course of disease (relapsing-remitting vs. chronic-progressive) non-significant differences were obtained across time of testing (initial test, retest) for each of the MMPI-2 scales. Sufficient power was obtained for the following scales at initial testing: Scale 8 (standard scoring method), power = .28, η2 = .077; Scale 3 (corrected scoring method), power = .32, η2 = .09; Scale 4 (corrected scoring method), power = .21, η2 = .05. At retest, sufficient power was obtained on Scale 4 (standard scoring method), power = .60, η2 = .175; Scale 6 (standard scoring method), power = .35, η2 = .096; Scale 4 (corrected scoring method), power = .48, η2 = .135. All results of power analyses were P < .05. Only results based on scales with sufficient power were used in group comparisons (relapsing-remitting vs. chronic-progressive). Demographic information is contained in Table 1. Controls from the previous study (Elder, 1999; N = 70; n = 51 females and n = 19 males) were used as a comparison group. They were randomly selected from 135 employees of the Veterans Affairs Medical Center (VAMC) in Coatesville, PA. Control participants had a mean age of 37.11 years (S.D. = 11.48) and mean educational level of 14.80 years. Ethnic background was Caucasian (n = 53), Latino (n = 8), Asian-American (n = 3), African-American (n = 3), and mixed descent. The majority was married (58.6%). Remaining participants were
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Table 1 Demographic information Variable
Mean (S.D.)
Frequency
Percentage
Age Year of education
48.68 (9.75) 15.07 (2.09)
Sex Female Male
21 7
75.0 25.0
Ethnicity Caucasian Other
26 2
92.9 7.1
Marital status Married Divorced Single Separated Widow/widower
13 9 4 1 1
46.4 32.0 14.3 3.6 3.6
Highest education level 8th to 11th grade High school graduate Bachelor level Master level
1 11 12 4
3.6 39.3 42.9 14.3
Career employment type Professional Skilled Semi-skilled Other
18 2 5 3
64.3 7.1 17.9 10.7
Disease course Chronic-progressive Relapsing-remitting Unknown
13 14 1
46.4 50.0 3.6
N = 28.
single (32.9%) or divorced (8.6%). Twenty-four percent held college degrees, 22.9% were at a master’s level, and 5.7% earned doctorates. Remaining participants had a high school education. Eighty-nine percent were employed at time of testing. 1.2. Procedure Participants with MS were administered the present test battery in their homes by a research assistant trained in this experimental procedure. Tests administered to the MS group consisted of a locally developed Sociodemographic Questionnaire and the MMPI-2. The Sociodemographic Questionnaire contained questions regarding demographic information, MS status (i.e., disease course), current medications, and psychiatric history. Specific information obtained through this questionnaire was then used as a basis for exclusion from the present study.
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Criteria for exclusion for both clinical and control groups were (1) <8th grade education, (2) a previously-diagnosed psychiatric disorder, (3) prior psychiatric treatment, and (4) drug or alcohol history. Participants who met any of the four criteria were denied participation in this study. Participants with MS were administered the MMPI-2 according to standard test instructions. Control participants from the previous study (Elder, 1999) were administered the MMPI-2 at their place of employment. Participants were asked to complete the test in one sitting and the research assistant returned approximately 2 hours later to pick it up. Only participants with valid MMPI-2 profiles were included in this study. Validity was determined in a manner consistent with previous research (e.g., Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989; Gass, 1991; Gass, 1992) by (1) less than 10 items omitted or double marked (i.e., the ? or Cannot Say Scale <10) as conservatively proposed by Graham (1993), (2) a raw score on Scale F <23 (Greene, 1991), a T-score on VRIN and TRIN of <80. Results from all 28 participants met these criteria for profile validity. Each of the MMPI-2 validity and clinical scales was hand-scored and proofed by two different trained research assistants.
2. Results In order to derive the correction procedure used in the present study, the original samples of 70 patients with MS and 70 controls from Elder (1999) were used. This correction procedure involved the following steps: (1) identification of items endorsed by >25% of patients with MS, (2) Chi square analyses with Yates’ correction to determine which items (from #1) significantly differentiated patients with MS from normal controls, and (3) principal components analysis to determine item inter-relatedness. This procedure is consistent with that used by Gass in his MMPI-2 correction studies (1991; 1992; 1996) and is described in detail in these studies, as well as in Elder (1999). In the present study, initial and retest data were first compared for stability over time. Results of Pearson correlations (two-tailed) between corrected test and corrected retest scores showed Scale L (r = .79, P < .01), Scale F (r = .54, P < .01), Scale K (r = .56, P < .01), Scale 1 (r = .70, P < .01), Scale 2 (r = .74, P < .01), Scale 3 (r = .69, P < .01), Scale 4 (r = .55, P < .01), Scale 5 (r = .55, P < .01), Scale 6 (r = .45, P < .05), Scale 7 (r = .47, P < .05), Scale 8 (r = .50, P < .01), Scale 9 (r = .52, P < .01), and Scale 0 (r = .80, P < .01), n = 26. Results contained in Table 2 show that most validity and basic scale scores were below a T-score of 65 (i.e., within normal limits). The exceptions to this fell on Scales 1–3, which ranged from T-score 65.32 to 73.61 on initial testing. These results held over time, with the only significant change in scores occurring on Scale 9, which dropped approximately five points upon retest (t = 2.21, P < .04). Test and retest scores on Scale 9 were both within normal limits. As indicated in Table 2, basic scale score elevations above a T-score of 65 were Scales 1, 3, and 2, in descending order of elevation. A correction procedure previously designed for MS patients was utilized (Elder, 1999). Major sources of variance in the MMPI-2 profiles of these MS patients were first determined by comparing frequency of item endorsement in the keyed direction with that of controls. Items endorsed by >25% of patients with MS (364 items) were retained for further analysis. Chi-square analysis with Yates’ correction was applied to the true–false response cells for the remaining
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Table 2 MMPI-2 uniform scale T-scores at initial testing and retest using the standard scoring method MMPI-2 scales
Uniform T-scores initial test, mean (S.D.)
Uniform T-scores retest, mean (S.D.)
L F K 1 2 3 4 5 6 7 8 9 0
55.86 (12.18) 53.54 (10.56) 53.50 (9.25) 73.61 (10.70) 65.32 (12.98) 73.04 (12.21) 53.68 (10.00) 52.14 (9.72) 54.79 (12.56) 58.64 (10.12) 63.82 (11.66) 52.68 (8.38) 46.68 (9.89)
55.48 (12.04) 54.25 (8.39) 54.29 (9.44) 71.75 (11.04) 64.57 (11.46) 73.00 (13.69) 53.68 (9.26) 54.44 (10.01) 51.21 (10.72) 57.89 (11.44) 63.50 (10.78) 49.43 (7.35) 47.68 (8.28)
N = 70.
Table 3 Factor structure of the 23 discriminating (correction) MMPI-2 items using patients with MS (rotated loading matrix (VARIMAX, gamma = 1.0000)) Item
Factor 1
Factor 2
Factor 3
10 12 43 45 53 91 141 147 148 152 164 165 175 177 179 224 247 295 296 464 475 476 561
.055 −.121 .501 −.246 .474 −.065 .246 .759 −.126 −.237 .572 .838 .362 .193 −.230 .237 .241 .040 .133 .488 .693 .151 .261
.272 .386 .127 .236 .544 .494 .376 .087 .358 .445 .041 −.039 .298 .825 .201 .013 .383 −.093 .437 −.264 .069 .493 .235
.460 .354 −.089 .539 −.061 .220 .357 .128 .301 .013 .041 .099 .305 −.142 .597 .447 .061 .579 .141 .559 −.084 .102 .379
Note. Percentage of total variance explained: 15.05% (Factor 1), 12.36% (Factor 2), and 10.59% (Factor 3).
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364 MMPI-2 items. Based on these analyses, an item subset (23 items) was identified that significantly differentiated MS patients from controls. Principal component analysis with VARIMAX rotation was next performed. Table 3 contains the results of this analysis (Elder, 1999). Three factors were extracted with eigenvalues >1. All three factors contained neurological content and these factors were retained as the correction item subset (19 items). A decision was made to restrict items in the correction item set to those from basic and validity scales only, so items 464; 475; 476; 561 (those following item 370) were removed from the set of 23 items derived through factor analysis. Table 4 contains the final set of 19 correction Table 4 Final set of MMPI-2 correction items by factor and type of scale using patients with MS (N = 70) Item no.
Item
MMPI-2 scales
Factor 1 43 130 147 164 165 175 464 475
My judgment is better than it ever was (F) I certainly feel useless at times (T) I cannot understand what I read as well as I used to (T) I seldom or never have dizzy spells (F) My memory seems to be all right (F) I feel weak all over much of the time (T) I feel tired a good deal of the time (T) Often I get confused and forget what to say (T)
2, Mt, APS 2, 7, Mt, DEP, LSE 2, 7, 8 1, 3, Re, HEA 2, 7, 8, PS 1, 2, 3, 7, HEA A, MT, WRK, PS PS, LSE
Parts of my body often have feelings like burning, tingling, crawling, or like “going to sleep” (T) I have little or no trouble with my muscles twitching or jumping (F) During the past few years I have been well most of the time (F) I have never felt better in my life than I do now (F) I do not tire quickly (F) My hands have not become clumsy or awkward (F) I have numbness in one or more places on my skin Sometimes my voice leaves me or changes even though I have no cold (T) I am very awkward and clumsy (T)
1, HEA
Factor 2 53 91 141 148 152 177 247 296 476 Factor 3 10 12 45 179 224 295 561
I am about as able to work as I ever was (F) My sex life is satisfactory (F) I am in just as good physical health as most of my friends (F) I have had no difficulty in keeping my balance in walking (F) I have few or no pains (F) I have never been paralyzed or had any unusual weakness of any of my muscles (F) I usually have enough energy to do my work (F)
1, 3, 8, HEA 1, 2, 3, PS, HEA K, 2, 3, Mt 1, 3, Mt 5, 8 1, 8, HEA 8, 0 Fb, LSE 1, 2, 3, R, Mt, WRK F, 4, 8, MDS 1, 2, 3, R, PS, HEA 1, 3, 8, HEA 1, 3, HEA 8, HEA WRK
Note. F = Infrequency, K = Correction, 1 = Scale Hs, 2 = Scale D, 3 = Scale Hy, 4 = Pd, 7 = Pt, 8 = Sc, 0 = Si, APS = Addiction Potential Content Scale, DEP = Depression Content, Fb = Back F Supplementary Scale, HEA = Health Concerns Content Scale, LSE = Low Self-Esteem Content Scale, MDS = Marital Distress Content Scale, Mt = College Maladjustment Supplementary Scale, PS = Post-Traumatic Stress Disorder Supplementary Scale, R = Repression Supplementary Scale, RE = Social Responsibility Supplementary Scale, and WRK = Work Interference Content Scale.
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items, by factor type. As noted in Table 4, Factor 1 accounted for 15.05% of the total variance (eigenvalue = 4.50), Factor 2 for 12.36% (eigenvalue = 2.75), and Factor 3 for 10.59% (eigenvalue = 1.80). Total variance explained by the three neurological factors was 38.00%. In the present study, these 19 items were then subtracted from their respective MMPI-2 validity and basic scales. Initial tests and retests were then re-scored. All scales except L, Masculinity/Femininity (Scale 5), and Paranoia (Scale 6), were represented in the correction item set. The K-corrected raw scores were then converted to uniform T-scores using a modified version of the standardization sample data contained in the test manual (Butcher et al., 1989). Modification of these data was conducted according to a procedure recommended by John McNulty (personal communication, February 6, 2001) and Auke Tellegen (personal communication, December 19, 2000) in which the 19 items were subtracted from results of the original MMPI-2 re-standardization sample and a corrected uniform T-score distribution was obtained. Because MS test and retest scale scores were demonstrated similar, only retest data were transformed into K-corrected uniform T-scores using this modified standardized T-score distribution. When the correction procedure was applied to retest data, statistically significant differences were obtained between corrected scale scores and scores derived using the traditional or standard scoring method (please see Table 5). The frequency of MS participants who scored >T-score of 65 at retest using the standard method of scoring the MMPI-2 (N = 28) was 3 (Scale F), 4 (Scale K), 22 (Scale 1), 11 (Scale 2), 22 (Scale 3), 2 (Scale 4), 7 (Scale 7), 12 (Scale 8), 2 (Scale 9), and 1 (Scale 0). The frequency of MS participants who scored >T-score of 65 at retest using the correction method (N = 28) was 3 (Scale F), 4 (Scale K), 4 (Scale 1), 2 (Scale 2), 6 (Scale 3), 2 (Scale 4), 3 (Scale 7), 1 (Scale 8), 2 (Scale 9), and 1 (Scale 0). Table 5 Comparisons between corrected and standard methods of scoring the MMPI-2 at retest using patients with MS MMPI-2 scales L F K 1 2 3 4 5 6 7 8 9 0 N = 28. ∗ P < .0001. ∗∗ P < .001. ∗∗∗ P < .05.
Uniform T-scores corrected, mean (S.D.) 53.64 (8.75) 53.57 (9.61) 60.21 (10.90) 58.14 (10.64) 61.86 (15.45) 51.86 (9.82)
54.04 (10.01) 55.54 (9.88) 48.57 (7.10) 49.46 (8.02)
Uniform T-scores standard scoring, mean (S.D.) 55.48 (12.04) 54.25 (8.38) 54.29 (9.45) 71.75 (11.05) 64.57 (11.46) 73.00 (13.69) 53.68 (9.26) 54.44 (10.89) 51.21 (10.72) 57.89 (11.44) 63.50 (10.78) 49.43 (7.35) 47.68 (8.28)
t (27) 1.59 3.73∗∗ 9.32∗ 9.23∗ 12.93∗ 4.11∗ 4.91∗ 8.32∗ 2.27∗∗∗ −4.10∗
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Scales which dropped five or more T-score points (clinically significant reduction) when the correction procedure was applied were Scales 1–3, 7, and 8. The number of patients who showed five or more T-score point drop between the standard method of scoring the MMPI-2 and the corrected method at retest was n = 27 (Scale 1), n = 23 (Scale 2), n = 28 (Scale 3), n = 11 (Scale 7), and n = 27 (Scale 8).
3. Discussion A major finding in the present study was that personality test scores based on the MMPI-2 were elevated as a function of complaints related to general health, work competency, and cognitive functioning. When a statistical correction procedure was applied to test results, scale scores dropped significantly. Clinical and statistical significance was demonstrated. Reliability of results was shown in terms of stability of scores over time (1 year). As seen here, patients with MS may inadvertently raise their clinical scale scores on the MMPI-2 by endorsing test items that inquire about physical symptoms. The disadvantage of interpreting psychopathology in this situation is that it may invite premature acceptance of test results as a true picture of the individual’s clinical standing. The correction approach offers clinicians the means to further examine emotional status in neurological samples. This approach avoids taking personality test results at face value and provides a means of further investigating the basis for physical or mental complaints (e.g., through follow-up interview). Results support that corrected scores represent the psychological status of patients with MS better than the uncorrected scores. Certainly, the primary way to determine this directly is to obtain external criterion information. Future studies may be designed to compare standard and corrected MMPI-2 scale scores with criterion information. Present results also support that a substantial number of patients with MS were affected by the correction procedure: on four of the MMPI-2 basic scales (Scales 1–3 and 8) an average of 26 subjects dropped five or more T-score points when profiles were corrected. Valid neurological symptoms and complaints assessed through the MMPI-2 have long been recognized as a source of variance that needs to be accounted for in test interpretation. This premise assumes that neurological complaints are valid and that they represent physical symptoms of a neurological, not psychological, condition. In MS, a disease known for its presentation of motor, visual, and cognitive disturbances, labeling physical problems as symptoms of an emotional condition may produce false positive interpretation. It is well documented that physical symptoms exist at high levels in a demyelinating disorder like MS. As advanced here, personality test results may not otherwise be elevated, except for the relatively high number of physical problems in this population. Based on these objective test results, the implication is that interpretations regarding emotional dysfunction in MS be made cautiously. Elevated clinical scale scores on the MMPI-2 may need to be queried by examiners, noting whether symptoms like lethargy, fatigue, low energy, low concentration, or poor memory are really signs of, for example, vegetative depression secondary to MS or primary physical symptoms of this disease. Neurotic triad configurations (caret; ascending slope; conversion “V”; descending slope) affecting MMPI-2 Scales 1–3 should receive special consideration. These scales were found to be more impacted by MS than
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other basic scales in the present study. Interpretations based on these clinical scale configurations typically involve psychosomatic features. In diseases like MS, psychosomatic tendencies or conversion defenses represented in these score configurations may not necessarily represent true personality features. Thus, interpreting an individual with MS as depressed, neurotic, or anxious without additional scoring and follow through may be premature. Application of this correction procedure was supported as a reliable scoring procedure with individuals suffering from MS. A uniform T-score transformation introduced here further strengthened the present MMPI-2 correction procedure. Correction items were subtracted from MMPI scales; raw scores were obtained, then entered into tables based on the re-standardization sample. While this method is appropriate when scoring according to the method recommended in the test manual, it seemed inappropriate when scale length was reduced. It could be argued that these two methods of scoring (i.e., corrected and standard) and their results are not equivalent and should be considered as such when deriving uniform T-scores. To address this issue, we incorporated a new method of deriving T-scores into the correction procedure in which uniform T-scores were developed in a manner identical to that used by MMPI-2 test developers. Re-standardization norms were revised to accommodate the reduced-item set and create a database similar in number of items per scale to that used in the present study. In so doing, results extended those of prototypic research and provided greater justification for applying a statistical correction to results of the MMPI-2 when patients with MS are tested. These findings hold potential clinical importance for individuals suffering from MS. Objective personality testing is commonly used with these patients, both clinically and in research studies, to assess emotional functioning. Research has shown that depression levels typically test high in this population. Anxiety is also frequently reported in the literature. Histrionic tendencies are likely, given elevated scores often seen on Scale 3. Results from numerous studies support high levels of emotional dysfunction in patients with debilitating diseases, such as MS. Current results strongly support a clinical scale configuration that matched this pattern. Clinicians and researchers alike are encouraged to probe somatic complaints further, looking for evidence of a physical, in addition to emotional etiology. Otherwise, test results may offer an incomplete picture of clinical functioning. As applied to one of the most widely used personality tests, the MMPI-2, this correction procedure offers clinicians the opportunity to engage in additional assessment to better distinguish physical from psychological complaints. In so doing, more reliable diagnoses may eventually be made regarding emotional disorders. Future studies should examine the effects of additional clinical evaluation on test interpretations. Clinicians might administer the MMPI-2, apply the correction procedure, then query the patient further based on results. Additional query may take the form of patient interview, content and supplementary scale analysis, or informant report.
Acknowledgments Gratitude is expressed to John McNulty and Auke Tellegen for their expertise. Their comments and assistance were invaluable to this study. Thanks also to the reviewers whose requests greatly improved procedures and interpretations. This research was supported, in part, through
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a grant to Linda D. Nelson and Tony Duc Do from the Undergraduate Research Opportunities Program of the University of California, Irvine. A portion of these findings was presented at the MMPI-2/MMPI-A 36th Annual Symposium (March 17, 2001).
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Measuring personality and emotional functioning in multiple sclerosis: a cautionary note Linda D. Nelson a,∗ , Joseph T. Elder b , Pany Tehrani a , Jantje Groot a a
Neurology Department, University of California, Irvine, Medical Center, 101 The City Drive, Route 81, Building 53, Room 225, Orange, CA 92868, USA b Atlanta Veteran Affairs Medical Center/Emory University School of Medicine, Atlanta, GA 30322, USA Accepted 25 April 2002
Abstract Changes in personality and emotional status are common in individuals with multiple sclerosis (MS). The purpose of this study was to examine results based on the MMPI-2 before and following application of a statistical correction procedure (Gass, 1992). This was done to help determine changes in scale score elevations when items containing actual physical symptoms are identified and statistically removed. Twenty-eight participants with MS were administered the MMPI-2, then retested 1 year later. Stability of MMPI-2 scores over time was demonstrated. Results showed that when the correction procedure was applied to the MMPI-2, eight standard clinical scale scores dropped an average of 6.66 T-score points. Significant differences were obtained between standard MMPI-2 scored profiles and corrected profiles on Scales 1–3 and 8. Cautious interpretation of MMPI-2 results for neurological samples was indicated. This study extended prototypic research by using patients with MS, examining the stability of results over time (1 year), and introducing a more reliable method of deriving standard T-scores in the correction procedure. © 2002 National Academy of Neuropsychology. Published by Elsevier Science Ltd. All rights reserved. Keywords: MMPI-2; Multiple sclerosis; Assessment; Emotional functioning; Personality; Neurological
Changes in personality and emotional functioning are common in multiple sclerosis (MS) (Beatty, 1993; Minden & Schieffer, 1990; Rodgers & Bland, 1996; Schiffer & Caine, 1991). These emotional changes pose a major challenge to patients, many of whom are also struggling with the concomitant and debilitating physical effects of their disease (Knight, Devereux, & Godfrey, 1997). Reliable assessment of secondary emotional problems is key to diagnosis ∗
Corresponding author. Tel.: +1-714-456-8311; fax: +1-714-456-8805. E-mail address: [email protected] (L.D. Nelson).
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and treatment planning. Unfortunately, reliable assessment of emotional functioning in neurological samples is not always possible using standard test methods. Normative standards for many of the available personality tests are based on the general population. Patients with neurological complaints are compared against these normative groups and not surprisingly are found to score significantly different. Many of these personality tests are self-reported and, while well-suited to the general population, may not be appropriate when special populations are considered. Personality test items that reflect physical and cognitive symptoms of central nervous system (CNS) diseases are administered to, and typically endorsed by people with CNS conditions. These items have face-value neurological content, including references to motor weakness, paresis, imbalance, incoordination, dysarthria, numbness, paresthesia, visual difficulties, tinnitus, and difficulties with concentration and memory. While many of these test items represent typical complaints of patients with MS, individuals with a primary psychiatric disturbance may express similar complaints, but for different reasons. Consequently, individuals with neurological problems inadvertently inflate scores from scales designed to measure symptoms of neurotic and psychotic conditions (Reitan & Wolfson, 1993). Endorsement of physical symptoms may increase scores from scales that were originally designed to measure psychopathology (Nyenhuis et al., 1995). Thus, elevated levels of emotional functioning based on the MMPI appear when none are in fact present. People who suffer from MS are faced with a serious disease of often unremitting and unpredictable proportions. Symptoms of MS can severely impair daily functioning and, at their worst, leave individuals wheelchair bound, blind, or incapable of caring for themselves. This chronic disease of the CNS is characterized by demyelination of axons, which delay or block transmission of nerve impulses (Hallpike, Adams, & Tourtellote, 1983). Medical features of the disease include a variety of physical symptoms, such as dizziness, fatigue, bladder problems, and loss of coordination (Hallpike et al., 1983). The age of onset is typically in the early twenties. Numerous investigators suspect that neurological content bias in the MMPI is particularly problematic when patients with MS are evaluated. Indeed, a number of “MS-related” test items have been identified on the MMPI (Baldwin, 1952; Elder, 1999; Marsh, Hirsch, & Leung, 1982; Meyerink, Reitan, & Selfz, 1988; Mueller & Girace, 1988). Thus, a test designed to measure personality and emotional functioning instead yields type and levels of impaired mental and physical functioning. The question of whether or not the individual is suffering from emotional problems, psychosomatic complaints, or true physical symptoms of the disease remains unanswered using the MMPI-2. The danger comes in false positive interpretations of emotional difficulties, instead of true expressions of a neurological state. Over 10 years ago, a review of the literature by Minden and Schieffer (1990) recommended that clinicians “use appropriate statistical analyses to determine whether somatic symptoms are biasing the results [of self-report inventories in neurological samples] (p. 103).” In the past 10 years, a number of studies were designed to determine what constituted “appropriate statistical analyses.” A relatively stringent three-stage empirical approach emerged, in which CNS-related items from the MMPI and MMPI-2 were identified (Edwards, Weissman, & Morrison, 1993; Gass, 1992; Gass, 1996). Item content purportedly measured common effects of focal brain lesions, such as motor and sensory impairments. The effects of statistically
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removing these test items on overall performance were determined. Results supported that personality test interpretations should include both the standard scoring method (as recommended in the test manual), as well as a method involving item removal and test rescoring. Gass and others advocated that clinicians apply each method when scoring the MMPI-2 to improve reliability of results for neurological patients. This study addressed the impact of endorsing specific MMPI-2 items. It was designed with the above considerations in mind, allowing for a neurological correction procedure developed and applied to the MMPI-2. Individuals with MS were selected for study because it is a neurological disease characterized by a high incidence of physical and mental complaints. As this study will demonstrate, apparent high levels of emotional problems will be identified that are more a physical manifestation of a neurological disease, than an actual emotional condition. This study extends prototypic research by using patients with MS, by examining stability of results over time (1 year) and by introducing a more reliable method of deriving standard T-scores to the correction procedure.
1. Method 1.1. Sample Participants were 28 individuals diagnosed with clinically definite MS by treating physicians who were selected from a larger MS study (Elder, 1999; N = 70). Mean time from date of diagnosis to date of initial testing was 11.22 (S.D. = 8.55) years. In the present study, 13 participants had a chronic-progressive course and 14 were relapsing-remitting at initial testing and retest. A chronic-progressive course is typically a continuous manifestation of symptoms. Relapsing-remitting pertains to a course in which symptoms remit for a period of time, then re-occur anywhere from months to years later. In one case, course was uncertain. When groups were compared by course of disease (relapsing-remitting vs. chronic-progressive) non-significant differences were obtained across time of testing (initial test, retest) for each of the MMPI-2 scales. Sufficient power was obtained for the following scales at initial testing: Scale 8 (standard scoring method), power = .28, η2 = .077; Scale 3 (corrected scoring method), power = .32, η2 = .09; Scale 4 (corrected scoring method), power = .21, η2 = .05. At retest, sufficient power was obtained on Scale 4 (standard scoring method), power = .60, η2 = .175; Scale 6 (standard scoring method), power = .35, η2 = .096; Scale 4 (corrected scoring method), power = .48, η2 = .135. All results of power analyses were P < .05. Only results based on scales with sufficient power were used in group comparisons (relapsing-remitting vs. chronic-progressive). Demographic information is contained in Table 1. Controls from the previous study (Elder, 1999; N = 70; n = 51 females and n = 19 males) were used as a comparison group. They were randomly selected from 135 employees of the Veterans Affairs Medical Center (VAMC) in Coatesville, PA. Control participants had a mean age of 37.11 years (S.D. = 11.48) and mean educational level of 14.80 years. Ethnic background was Caucasian (n = 53), Latino (n = 8), Asian-American (n = 3), African-American (n = 3), and mixed descent. The majority was married (58.6%). Remaining participants were
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Table 1 Demographic information Variable
Mean (S.D.)
Frequency
Percentage
Age Year of education
48.68 (9.75) 15.07 (2.09)
Sex Female Male
21 7
75.0 25.0
Ethnicity Caucasian Other
26 2
92.9 7.1
Marital status Married Divorced Single Separated Widow/widower
13 9 4 1 1
46.4 32.0 14.3 3.6 3.6
Highest education level 8th to 11th grade High school graduate Bachelor level Master level
1 11 12 4
3.6 39.3 42.9 14.3
Career employment type Professional Skilled Semi-skilled Other
18 2 5 3
64.3 7.1 17.9 10.7
Disease course Chronic-progressive Relapsing-remitting Unknown
13 14 1
46.4 50.0 3.6
N = 28.
single (32.9%) or divorced (8.6%). Twenty-four percent held college degrees, 22.9% were at a master’s level, and 5.7% earned doctorates. Remaining participants had a high school education. Eighty-nine percent were employed at time of testing. 1.2. Procedure Participants with MS were administered the present test battery in their homes by a research assistant trained in this experimental procedure. Tests administered to the MS group consisted of a locally developed Sociodemographic Questionnaire and the MMPI-2. The Sociodemographic Questionnaire contained questions regarding demographic information, MS status (i.e., disease course), current medications, and psychiatric history. Specific information obtained through this questionnaire was then used as a basis for exclusion from the present study.
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Criteria for exclusion for both clinical and control groups were (1) <8th grade education, (2) a previously-diagnosed psychiatric disorder, (3) prior psychiatric treatment, and (4) drug or alcohol history. Participants who met any of the four criteria were denied participation in this study. Participants with MS were administered the MMPI-2 according to standard test instructions. Control participants from the previous study (Elder, 1999) were administered the MMPI-2 at their place of employment. Participants were asked to complete the test in one sitting and the research assistant returned approximately 2 hours later to pick it up. Only participants with valid MMPI-2 profiles were included in this study. Validity was determined in a manner consistent with previous research (e.g., Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989; Gass, 1991; Gass, 1992) by (1) less than 10 items omitted or double marked (i.e., the ? or Cannot Say Scale <10) as conservatively proposed by Graham (1993), (2) a raw score on Scale F <23 (Greene, 1991), a T-score on VRIN and TRIN of <80. Results from all 28 participants met these criteria for profile validity. Each of the MMPI-2 validity and clinical scales was hand-scored and proofed by two different trained research assistants.
2. Results In order to derive the correction procedure used in the present study, the original samples of 70 patients with MS and 70 controls from Elder (1999) were used. This correction procedure involved the following steps: (1) identification of items endorsed by >25% of patients with MS, (2) Chi square analyses with Yates’ correction to determine which items (from #1) significantly differentiated patients with MS from normal controls, and (3) principal components analysis to determine item inter-relatedness. This procedure is consistent with that used by Gass in his MMPI-2 correction studies (1991; 1992; 1996) and is described in detail in these studies, as well as in Elder (1999). In the present study, initial and retest data were first compared for stability over time. Results of Pearson correlations (two-tailed) between corrected test and corrected retest scores showed Scale L (r = .79, P < .01), Scale F (r = .54, P < .01), Scale K (r = .56, P < .01), Scale 1 (r = .70, P < .01), Scale 2 (r = .74, P < .01), Scale 3 (r = .69, P < .01), Scale 4 (r = .55, P < .01), Scale 5 (r = .55, P < .01), Scale 6 (r = .45, P < .05), Scale 7 (r = .47, P < .05), Scale 8 (r = .50, P < .01), Scale 9 (r = .52, P < .01), and Scale 0 (r = .80, P < .01), n = 26. Results contained in Table 2 show that most validity and basic scale scores were below a T-score of 65 (i.e., within normal limits). The exceptions to this fell on Scales 1–3, which ranged from T-score 65.32 to 73.61 on initial testing. These results held over time, with the only significant change in scores occurring on Scale 9, which dropped approximately five points upon retest (t = 2.21, P < .04). Test and retest scores on Scale 9 were both within normal limits. As indicated in Table 2, basic scale score elevations above a T-score of 65 were Scales 1, 3, and 2, in descending order of elevation. A correction procedure previously designed for MS patients was utilized (Elder, 1999). Major sources of variance in the MMPI-2 profiles of these MS patients were first determined by comparing frequency of item endorsement in the keyed direction with that of controls. Items endorsed by >25% of patients with MS (364 items) were retained for further analysis. Chi-square analysis with Yates’ correction was applied to the true–false response cells for the remaining
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Table 2 MMPI-2 uniform scale T-scores at initial testing and retest using the standard scoring method MMPI-2 scales
Uniform T-scores initial test, mean (S.D.)
Uniform T-scores retest, mean (S.D.)
L F K 1 2 3 4 5 6 7 8 9 0
55.86 (12.18) 53.54 (10.56) 53.50 (9.25) 73.61 (10.70) 65.32 (12.98) 73.04 (12.21) 53.68 (10.00) 52.14 (9.72) 54.79 (12.56) 58.64 (10.12) 63.82 (11.66) 52.68 (8.38) 46.68 (9.89)
55.48 (12.04) 54.25 (8.39) 54.29 (9.44) 71.75 (11.04) 64.57 (11.46) 73.00 (13.69) 53.68 (9.26) 54.44 (10.01) 51.21 (10.72) 57.89 (11.44) 63.50 (10.78) 49.43 (7.35) 47.68 (8.28)
N = 70.
Table 3 Factor structure of the 23 discriminating (correction) MMPI-2 items using patients with MS (rotated loading matrix (VARIMAX, gamma = 1.0000)) Item
Factor 1
Factor 2
Factor 3
10 12 43 45 53 91 141 147 148 152 164 165 175 177 179 224 247 295 296 464 475 476 561
.055 −.121 .501 −.246 .474 −.065 .246 .759 −.126 −.237 .572 .838 .362 .193 −.230 .237 .241 .040 .133 .488 .693 .151 .261
.272 .386 .127 .236 .544 .494 .376 .087 .358 .445 .041 −.039 .298 .825 .201 .013 .383 −.093 .437 −.264 .069 .493 .235
.460 .354 −.089 .539 −.061 .220 .357 .128 .301 .013 .041 .099 .305 −.142 .597 .447 .061 .579 .141 .559 −.084 .102 .379
Note. Percentage of total variance explained: 15.05% (Factor 1), 12.36% (Factor 2), and 10.59% (Factor 3).
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364 MMPI-2 items. Based on these analyses, an item subset (23 items) was identified that significantly differentiated MS patients from controls. Principal component analysis with VARIMAX rotation was next performed. Table 3 contains the results of this analysis (Elder, 1999). Three factors were extracted with eigenvalues >1. All three factors contained neurological content and these factors were retained as the correction item subset (19 items). A decision was made to restrict items in the correction item set to those from basic and validity scales only, so items 464; 475; 476; 561 (those following item 370) were removed from the set of 23 items derived through factor analysis. Table 4 contains the final set of 19 correction Table 4 Final set of MMPI-2 correction items by factor and type of scale using patients with MS (N = 70) Item no.
Item
MMPI-2 scales
Factor 1 43 130 147 164 165 175 464 475
My judgment is better than it ever was (F) I certainly feel useless at times (T) I cannot understand what I read as well as I used to (T) I seldom or never have dizzy spells (F) My memory seems to be all right (F) I feel weak all over much of the time (T) I feel tired a good deal of the time (T) Often I get confused and forget what to say (T)
2, Mt, APS 2, 7, Mt, DEP, LSE 2, 7, 8 1, 3, Re, HEA 2, 7, 8, PS 1, 2, 3, 7, HEA A, MT, WRK, PS PS, LSE
Parts of my body often have feelings like burning, tingling, crawling, or like “going to sleep” (T) I have little or no trouble with my muscles twitching or jumping (F) During the past few years I have been well most of the time (F) I have never felt better in my life than I do now (F) I do not tire quickly (F) My hands have not become clumsy or awkward (F) I have numbness in one or more places on my skin Sometimes my voice leaves me or changes even though I have no cold (T) I am very awkward and clumsy (T)
1, HEA
Factor 2 53 91 141 148 152 177 247 296 476 Factor 3 10 12 45 179 224 295 561
I am about as able to work as I ever was (F) My sex life is satisfactory (F) I am in just as good physical health as most of my friends (F) I have had no difficulty in keeping my balance in walking (F) I have few or no pains (F) I have never been paralyzed or had any unusual weakness of any of my muscles (F) I usually have enough energy to do my work (F)
1, 3, 8, HEA 1, 2, 3, PS, HEA K, 2, 3, Mt 1, 3, Mt 5, 8 1, 8, HEA 8, 0 Fb, LSE 1, 2, 3, R, Mt, WRK F, 4, 8, MDS 1, 2, 3, R, PS, HEA 1, 3, 8, HEA 1, 3, HEA 8, HEA WRK
Note. F = Infrequency, K = Correction, 1 = Scale Hs, 2 = Scale D, 3 = Scale Hy, 4 = Pd, 7 = Pt, 8 = Sc, 0 = Si, APS = Addiction Potential Content Scale, DEP = Depression Content, Fb = Back F Supplementary Scale, HEA = Health Concerns Content Scale, LSE = Low Self-Esteem Content Scale, MDS = Marital Distress Content Scale, Mt = College Maladjustment Supplementary Scale, PS = Post-Traumatic Stress Disorder Supplementary Scale, R = Repression Supplementary Scale, RE = Social Responsibility Supplementary Scale, and WRK = Work Interference Content Scale.
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items, by factor type. As noted in Table 4, Factor 1 accounted for 15.05% of the total variance (eigenvalue = 4.50), Factor 2 for 12.36% (eigenvalue = 2.75), and Factor 3 for 10.59% (eigenvalue = 1.80). Total variance explained by the three neurological factors was 38.00%. In the present study, these 19 items were then subtracted from their respective MMPI-2 validity and basic scales. Initial tests and retests were then re-scored. All scales except L, Masculinity/Femininity (Scale 5), and Paranoia (Scale 6), were represented in the correction item set. The K-corrected raw scores were then converted to uniform T-scores using a modified version of the standardization sample data contained in the test manual (Butcher et al., 1989). Modification of these data was conducted according to a procedure recommended by John McNulty (personal communication, February 6, 2001) and Auke Tellegen (personal communication, December 19, 2000) in which the 19 items were subtracted from results of the original MMPI-2 re-standardization sample and a corrected uniform T-score distribution was obtained. Because MS test and retest scale scores were demonstrated similar, only retest data were transformed into K-corrected uniform T-scores using this modified standardized T-score distribution. When the correction procedure was applied to retest data, statistically significant differences were obtained between corrected scale scores and scores derived using the traditional or standard scoring method (please see Table 5). The frequency of MS participants who scored >T-score of 65 at retest using the standard method of scoring the MMPI-2 (N = 28) was 3 (Scale F), 4 (Scale K), 22 (Scale 1), 11 (Scale 2), 22 (Scale 3), 2 (Scale 4), 7 (Scale 7), 12 (Scale 8), 2 (Scale 9), and 1 (Scale 0). The frequency of MS participants who scored >T-score of 65 at retest using the correction method (N = 28) was 3 (Scale F), 4 (Scale K), 4 (Scale 1), 2 (Scale 2), 6 (Scale 3), 2 (Scale 4), 3 (Scale 7), 1 (Scale 8), 2 (Scale 9), and 1 (Scale 0). Table 5 Comparisons between corrected and standard methods of scoring the MMPI-2 at retest using patients with MS MMPI-2 scales L F K 1 2 3 4 5 6 7 8 9 0 N = 28. ∗ P < .0001. ∗∗ P < .001. ∗∗∗ P < .05.
Uniform T-scores corrected, mean (S.D.) 53.64 (8.75) 53.57 (9.61) 60.21 (10.90) 58.14 (10.64) 61.86 (15.45) 51.86 (9.82)
54.04 (10.01) 55.54 (9.88) 48.57 (7.10) 49.46 (8.02)
Uniform T-scores standard scoring, mean (S.D.) 55.48 (12.04) 54.25 (8.38) 54.29 (9.45) 71.75 (11.05) 64.57 (11.46) 73.00 (13.69) 53.68 (9.26) 54.44 (10.89) 51.21 (10.72) 57.89 (11.44) 63.50 (10.78) 49.43 (7.35) 47.68 (8.28)
t (27) 1.59 3.73∗∗ 9.32∗ 9.23∗ 12.93∗ 4.11∗ 4.91∗ 8.32∗ 2.27∗∗∗ −4.10∗
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Scales which dropped five or more T-score points (clinically significant reduction) when the correction procedure was applied were Scales 1–3, 7, and 8. The number of patients who showed five or more T-score point drop between the standard method of scoring the MMPI-2 and the corrected method at retest was n = 27 (Scale 1), n = 23 (Scale 2), n = 28 (Scale 3), n = 11 (Scale 7), and n = 27 (Scale 8).
3. Discussion A major finding in the present study was that personality test scores based on the MMPI-2 were elevated as a function of complaints related to general health, work competency, and cognitive functioning. When a statistical correction procedure was applied to test results, scale scores dropped significantly. Clinical and statistical significance was demonstrated. Reliability of results was shown in terms of stability of scores over time (1 year). As seen here, patients with MS may inadvertently raise their clinical scale scores on the MMPI-2 by endorsing test items that inquire about physical symptoms. The disadvantage of interpreting psychopathology in this situation is that it may invite premature acceptance of test results as a true picture of the individual’s clinical standing. The correction approach offers clinicians the means to further examine emotional status in neurological samples. This approach avoids taking personality test results at face value and provides a means of further investigating the basis for physical or mental complaints (e.g., through follow-up interview). Results support that corrected scores represent the psychological status of patients with MS better than the uncorrected scores. Certainly, the primary way to determine this directly is to obtain external criterion information. Future studies may be designed to compare standard and corrected MMPI-2 scale scores with criterion information. Present results also support that a substantial number of patients with MS were affected by the correction procedure: on four of the MMPI-2 basic scales (Scales 1–3 and 8) an average of 26 subjects dropped five or more T-score points when profiles were corrected. Valid neurological symptoms and complaints assessed through the MMPI-2 have long been recognized as a source of variance that needs to be accounted for in test interpretation. This premise assumes that neurological complaints are valid and that they represent physical symptoms of a neurological, not psychological, condition. In MS, a disease known for its presentation of motor, visual, and cognitive disturbances, labeling physical problems as symptoms of an emotional condition may produce false positive interpretation. It is well documented that physical symptoms exist at high levels in a demyelinating disorder like MS. As advanced here, personality test results may not otherwise be elevated, except for the relatively high number of physical problems in this population. Based on these objective test results, the implication is that interpretations regarding emotional dysfunction in MS be made cautiously. Elevated clinical scale scores on the MMPI-2 may need to be queried by examiners, noting whether symptoms like lethargy, fatigue, low energy, low concentration, or poor memory are really signs of, for example, vegetative depression secondary to MS or primary physical symptoms of this disease. Neurotic triad configurations (caret; ascending slope; conversion “V”; descending slope) affecting MMPI-2 Scales 1–3 should receive special consideration. These scales were found to be more impacted by MS than
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other basic scales in the present study. Interpretations based on these clinical scale configurations typically involve psychosomatic features. In diseases like MS, psychosomatic tendencies or conversion defenses represented in these score configurations may not necessarily represent true personality features. Thus, interpreting an individual with MS as depressed, neurotic, or anxious without additional scoring and follow through may be premature. Application of this correction procedure was supported as a reliable scoring procedure with individuals suffering from MS. A uniform T-score transformation introduced here further strengthened the present MMPI-2 correction procedure. Correction items were subtracted from MMPI scales; raw scores were obtained, then entered into tables based on the re-standardization sample. While this method is appropriate when scoring according to the method recommended in the test manual, it seemed inappropriate when scale length was reduced. It could be argued that these two methods of scoring (i.e., corrected and standard) and their results are not equivalent and should be considered as such when deriving uniform T-scores. To address this issue, we incorporated a new method of deriving T-scores into the correction procedure in which uniform T-scores were developed in a manner identical to that used by MMPI-2 test developers. Re-standardization norms were revised to accommodate the reduced-item set and create a database similar in number of items per scale to that used in the present study. In so doing, results extended those of prototypic research and provided greater justification for applying a statistical correction to results of the MMPI-2 when patients with MS are tested. These findings hold potential clinical importance for individuals suffering from MS. Objective personality testing is commonly used with these patients, both clinically and in research studies, to assess emotional functioning. Research has shown that depression levels typically test high in this population. Anxiety is also frequently reported in the literature. Histrionic tendencies are likely, given elevated scores often seen on Scale 3. Results from numerous studies support high levels of emotional dysfunction in patients with debilitating diseases, such as MS. Current results strongly support a clinical scale configuration that matched this pattern. Clinicians and researchers alike are encouraged to probe somatic complaints further, looking for evidence of a physical, in addition to emotional etiology. Otherwise, test results may offer an incomplete picture of clinical functioning. As applied to one of the most widely used personality tests, the MMPI-2, this correction procedure offers clinicians the opportunity to engage in additional assessment to better distinguish physical from psychological complaints. In so doing, more reliable diagnoses may eventually be made regarding emotional disorders. Future studies should examine the effects of additional clinical evaluation on test interpretations. Clinicians might administer the MMPI-2, apply the correction procedure, then query the patient further based on results. Additional query may take the form of patient interview, content and supplementary scale analysis, or informant report.
Acknowledgments Gratitude is expressed to John McNulty and Auke Tellegen for their expertise. Their comments and assistance were invaluable to this study. Thanks also to the reviewers whose requests greatly improved procedures and interpretations. This research was supported, in part, through
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a grant to Linda D. Nelson and Tony Duc Do from the Undergraduate Research Opportunities Program of the University of California, Irvine. A portion of these findings was presented at the MMPI-2/MMPI-A 36th Annual Symposium (March 17, 2001).
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