THE EXECUTIVE INTERVIEW 1 is not a structured interview

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1 ORIGINAL ARTICLE Rasch Analysis of the Executive Interview (The EXIT-25) and Introduction of an Abridged Version (The Quick EXIT) Eric B. Larson, PhD, ABPP, Allen W. Heinemann, PhD, ABPP 389 ABSTRACT. Larson EB, Heinemann AW. Rasch analysis of the Executive Interview (The EXIT-25) and introduction of an abridged version (The Quick Exit). Arch Phys Med Rehabil 2010;91: Objectives: To evaluate the psychometric properties of the Executive Interview (EXIT-25) and to propose modifications that will improve those properties. Design: Rasch analysis of existing datasets contributed by 3 prior projects, all of which examined criterion-related validity of the EXIT-25. Setting: A large, urban, academic free-standing rehabilitation facility. Participants: The sample of 147 was comprised of 109 adults diagnosed with stroke evaluated during inpatient rehabilitation and 38 adults with traumatic brain injury evaluated during inpatient (n 11) or outpatient rehabilitation (n 27). Interventions: Not applicable. Main Outcome Measures: The EXIT-25, Repeatable Battery for the Assessment of Neuropsychological Status, and Trails A and B. Results: Eleven of the 25 items correlated weakly with the total measure and misfit the rating scale model. Deleting these 11 items improved the internal consistency of the remaining 14 items and enhanced the measure s criterion-related validity. Conclusions: The EXIT-25 can be reduced from 25 to 14 items without reducing internal consistency. Convergent validity of the abbreviated measure is supported by moderate-size correlations with standard measures of cognitive deficits. Key Words: Brain injuries; Cognition; Frontal lobe; Mental processes; Neuropsychological tests; Psychometrics; Rehabilitation; Stroke by the American Congress of Rehabilitation Medicine From the Rehabilitation Institute of Chicago, Feinberg School of Medicine, Northwestern University, Chicago, IL. Supported in part by the U.S. Department of Education, National Institute on Disability and Rehabilitation Research, (grant no. H133B30024) through the Rehabilitation Research and Training Center on Enhancing Quality of Life of Stroke Survivors, and the Midwest Regional Traumatic Brain Injury Model System: Innovative Approaches to Improve Cognition, Function, and Community Living (grant no. HI33N060014). No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated. Correspondence to Eric B. Larson, Rehabilitation Institute of Chicago, 345 E. Superior St., Chicago, IL elarson@ric.org. Reprints are not available from the author /10/ $36.00/0 doi: /j.apmr THE EXECUTIVE INTERVIEW 1 is not a structured interview but rather a brief bedside test of executive functions. It consists of 25 items measuring abilities such as motor sequencing (Luria hand sequences), spoken alternate sequencing, verbal fluency, design fluency, persistence, and resistance to interference (a go-no-go item, an anomalous sentence repetition item, a Stroop item). Other items measure reflexes (eg, snout reflex, grasp reflex) or are designed to elicit echopraxia or automatic behavior (utilization behavior). Items are scored by the examiner on a scale of 0 (no impairment) to 2 (severe impairment); larger scores indicate more severe deficits. Royall et al 2 suggested a cutoff of 15 to discriminate normal elderly subjects from those with dementias. A score greater than 15 indicates moderate to severe impairment of executive function. Mildly demented patients have been found to score as low as 7, and in 1 study the authors found that a lower (less impaired) cutoff of 11 was ideal to distinguish people with dementia in a sample of HIV/acquired immunodeficiency syndrome patients. 3,4 Literature Review The EXIT-25 was developed to assess cognitive function of older adults who are residents of retirement communities, 1 but subsequent research established its utility for other populations. It is sensitive to differences in cognitive function in patients with a variety of diagnoses including HIV dementia, 3 mild dementia in mixed neurologic samples, 4 bipolar disorder, 5 Alzheimer s dementia, and frontal-temporal dementia. 6 It is more sensitive than other brief cognitive measures. In a sample of patients with bipolar disorder, the EXIT-25 detected 44% more cases of a comorbid Diagnostic and Statistical Manual of Mental Disorders, 4th edition diagnosis of cognitive disorder than the MMSE. 7 The EXIT-25 reduces diagnosis misclassification and improves sensitivity when used to detect early stages of dementia. 8 Its sensitivity and specificity for decision-making ability is superior to the MMSE Trails A and B in patients with Parkinson s disease. 9 It accurately classifies the level of care in several studies, including diagnostically mixed samples in retirement communities 1,10-12 and in a schizophrenia sample. 13 The EXIT-25 can detect abnormalities identified with brain imaging. Impaired scores on the EXIT-25 were found in subjects with cortical lesions in the right frontal, right medial, left frontal, and left medial areas. 14 The EXIT-25 has strong associations with other established neuropsychologic tests. In its pilot validation study, strong correlations were found with the MMSE Trails A and B, the Test of Sustained Attention, and the Wisconsin Card Sorting Test. 1 In a sample of geriatric psychiatry patients, it correlated with the Mattis DRS and the Controlled Oral Word Association Test. 15 In a sample of outpatients with TBI, it correlated with the MMSE, Modified Mini-Mental State, Beck Depression Inventory 2nd, edition, and the Stroop. 16 In a sample of older EXIT-25 HIV MMSE RBANS TBI List of Abbreviations Executive Interview human immunodeficiency virus Mini-Mental State Examination Repeatable Battery for the Assessment of Neuropsychological Status traumatic brain injury

2 390 RASCH ANALYSIS OF THE EXECUTIVE INTERVIEW (THE EXIT-25), Larson adults, it correlated with the California Verbal Learning Test 2nd edition. 17 In a group of outpatients with mild dementia, it correlated with category fluency and lexical fluency but not with the Wisconsin Card Sort or Trails B. 4 Validation studies have examined the instrument s association with clinical ratings of disability. The degree of impairment on EXIT-25 and MMSE correlated with ratings of need for assistance based on the Older Americans Resources and Services Instrument. 18 In inpatients and outpatients with TBI, the EXIT-25 correlated with FIM ratings of cognitive disability after controlling for general mental status as measured by the MMSE. 16 However, in a sample of outpatients with mild dementia, no correlation was found between the EXIT-25 and disability in every day functioning. 4 The presence and severity of problem behaviors are associated with performance on the EXIT-25 in patients with HIV 19 and in nursing home residents. 20 The EXIT-25 has been used to detect change in clinical trials and in longitudinal research in older adults 21 and in women with breast cancer. 22,23 The evidence of discriminant validity is provided by low correlations with variables unrelated to neurocognitive pathology including depression 15 and physical disability. 16 Several limitations become apparent when the measure is used with adults who have acquired brain injury. The poor face validity of several items is disconcerting to patients who expect a battery of cognitive tests. The content validity is also questionable. The time required for administration is another drawback. The MMSE Trails A and B and the Stroop can be administered in about 5 minutes each, and the Wisconsin Card Sorting Test can be completed in about 10 minutes; in contrast, the EXIT-25 requires about 15 minutes. In clinical settings in which neuropsychologists have limited time, longer tests are disadvantageous. A brief version of the EXIT-25 that requires less time to administer would benefit patients in rehabilitation settings. Thus, the objective of this study was to identify a subset of items that measure a unidimensional construct that could be used to characterize patients mental organization and better inform assessments of independent functioning. It was our intent that the resulting short form would be less intrusive, would retain the reliability and criterion-related validity of the full version, and would show improved content validity. Hypotheses were (1) the EXIT-25 can be reduced in length without reducing internal consistency and (2) convergent validity of a reduced-length EXIT is supported by moderate-size correlations with standard measures of cognitive deficits. METHODS Sample The sample of 147 included stroke patients assessed during inpatient rehabilitation (n 109), TBI patients assessed during inpatient rehabilitation (n 11), and TBI patients receiving outpatient services (n 27). The total sample consisted of 81 men and 66 women; their mean age SD was years (range, 18 88y). Patients were recruited as part of ongoing studies, and subsamples completed additional tests as part of several different study protocols. Instruments The stroke patients completed extensive neuropsychologic testing. In addition to the EXIT-25, this battery included the following measures. The Repeatable Battery for the Assessment of Neuropsychological Status 24 is a brief instrument for detecting and characterizing cognitive decline. Administration requires 20 to 30 minutes and can be completed at bedside. It yields a total score and indices for 5 cognitive domains including an Immediate Memory Index, a Visuospatial/Constructional Index, a Language Index, an Attention Index and a Delayed Recall Index. The Trailmaking Test 25 consists of 2 parts. In part A, the subject is presented with a page containing a dispersed array of numbered circles and is asked to draw a line to numbers in sequential order as quickly as possible. Part B is similar but involves an alternating alphanumeric sequence. Statistical Methods Rasch analysis 26,27 yields a hierarchy of item difficulties and a hierarchy of person abilities from most to least impaired. Of the psychometric indices this analysis provides, we examined 4. Item misfit describes the extent to which the sample as a whole responds unexpectedly to specific items. Values between 0.7 and 1.3 are desirable. Values greater than 1.3 represent excessive noise caused by unexpected responses. This index is similar to chi-square analyses that examine the residuals between expected and observed responses. Item separation reflects the range of function assessed by a test. Desirable values exceed 2.0, which correspond to a Cronbach alpha of.80. Person separation refers to the number of functional strata represented in a sample; values greater than 2.0 are desirable. Person misfit is the extent to which subjects respond idiosyncratically to the item set; misfit is defined by outfit values exceeding a z score of 2.0. We report the percentage of persons with values over this cutoff. Rating scale structure describes the use of rating scale categories across items. Higher ratings on individual items should be associated with higher total scores. Step disorder reflects inconsistencies between individual item ratings and total test scores. We used Winsteps software a to complete Rasch analysis of the EXIT-25 based on a modern test theory. For the purposes of comparison using a different model, we used SPSS (version 14, 2005) b to obtain estimates of internal consistency by using classic test theory methods. We also used SPSS to compute correlations between a battery of neuropsychologic tests and 2 versions of the EXIT, the original 25-item test and a 14-item version. RESULTS Preliminary analysis of the EXIT-25 using the original coding structure revealed 13 items with fewer than 10 observations per category. The rating scale responses increased monotonically, but response option 1 (moderately impaired) was never the most probable response. In addition, item misfit was a problem with mean square outfit values as large as Person misfit was acceptable for the EXIT-25 in that only 2.7% of the sample had values greater than 2.0. Item separation was 4.8, and person separation was 1.90, which is below the desired minimum value of 2.0. The corresponding item reliability was.98, and person reliability was.78. Item-measure correlations ranged from.07 to.70. Simple correlations between items and the total score revealed similar values. Although reliability was acceptable (Cronbach.86), item-total correlations ranged from.07 to.81; 4 values were less than.30 (table 1). We attempted to address the step structure problem by combining scores of 0 and 1. This 2-category analysis resulted in worse person separation and in less than 2 functional strata, which is the minimum recommended by Linacre. 28 Thus, we decided to retain the original 3-category rating structure (0 low impairment, 1 moderate impairment, 2 severe impairment). As an alternate approach, we dropped 11 items with

3 RASCH ANALYSIS OF THE EXECUTIVE INTERVIEW (THE EXIT-25), Larson 391 Table 1: Pearson Product-Moment Correlations: Comparison of the EXIT-25 and the Quick EXIT EXIT-25 Total Score Quick EXIT Total Score EXIT items Number-letter task Word fluency Design fluency Anomalous sentence Repetition Thematic perception Memory/distraction task Interference task Automatic behavior I Automatic behavior II.28* 147 Grasp reflex Social habit I Motor impersistence Snout reflex Finger-nose-finger task.28* 147 Go/no-go task Echopraxia I Luria hand sequence I Luria hand sequence II Echopraxia II Grip task Complex command task Serial order reversal task Counting task Utilization behavior Imitation behavior Neuropsychologic measures RBANS attention.37* RBANS language RBANS Vis/Con.34*.33* 72 RBANS Imm Mem RBANS Del Mem Trails A Trails B.45*.45* 51 Abbreviations: Vis/Con, visuospatial/constructional; Imm Mem, immediate memory; Del Mem, delayed memory. *P.01. P large infit or outfit mean square values or with low itemmeasure correlations (Automatic Behavior I, Automatic Behavior II, Grasp Reflex, Social Habit I, Snout Reflex, Finger- Nose-Finger, Echopraxia II, Complex Command, Counting I, Utilization Behavior, and Imitation Behavior). Consequently, using the original rating structure with the 14 retained items yielded a possible range in total score from 0 to 28. The resulting 14-item short form met 3 of Linacre s criteria including (1) the average measure advances monotonically across rating scale categories, (2) step calibrations advance monotonically, and (3) category infit mean square values are less than 1.5. Two criteria were not fulfilled: 4 items had fewer than 10 observations per category, and there was a minor inversion in step structure (data not shown). Only 3 of the 14 items had misfit values greater than 1.3, the largest of which was 1.46 (data not shown). Person misfit improved; only 2.0% of the sample had values exceeding 2.0. Item separation improved to 6.13, revealing that the sample s performance distinguishes a wide range of item difficulties. Person separation improved to The corresponding item reliability increased to.97, and person reliability improved to.80. Item-measure correlations N were stronger, with no value less than.43. Simple correlations between items and the total score also improved. Internal consistency improved (Cronbach.88) as did item-total correlations, ranging from.46 to.82 (see table 1). As mentioned previously, 3 cases had misfit values exceeding 2.0 in the 14-item version. The most misfitting case was a 56-year-old woman with 11 years of education who was diagnosed with ischemic stroke affecting the left internal capsule. Speech therapists noted mild to moderate Broca aphasia. Physical and occupational therapists gave her a motor FIM score of 60 at discharge, indicating moderate disability. Rasch analysis showed unusual responses on Design Fluency, Number Letter Sequencing and Thematic Perception. She performed surprisingly well on the latter 2 items, showing a remarkable recovery of mental flexibility and the ability to articulate a complex description. In contrast, her score on Design Fluency was unexpectedly poor, probably reflecting a reduced ability to use a pencil, because of her loss of motor control. Another misfitting case was a 31-year-old woman with 11 years of education who was diagnosed with left frontal intracerebral hemorrhage. Speech therapists diagnosed a moderate to severe undifferentiated aphasia. Rasch analysis showed unusual responses on Echopraxia, Grip, and Design Fluency. Her difficulty on the Echopraxia item reflects a tendency to imitate gestures rather than follow commands, possibly because of reduced auditory comprehension. Her response to the Grip item (in which she pulled the examiner s fingers together) may also reflect a reduced comprehension of instructions. Although she obtained impaired scores on many other items, she did unusually well on Design Fluency, possibly because this task exerts fewer demands on expressive language and because the examiner demonstration requires less auditory comprehension. Figure 1 shows the map of persons and items of the 14 retained items. As indicated in the positions of the mean person measures and item calibrations (designated by the M on each side of the continuum in figure 1), the item set was slightly mistargeted on this sample, given the 1 logit difference between the mean item difficulty (set at 0) and the mean person ability. As a group, the sample was not severely impaired in executive function, and the item set was targeted toward greater impairment. The most difficult items assessing executive functions were Design Fluency, Word Fluency and Memory/Distraction; the easiest items were Echopraxia and Motor Impersistence. The map illustrates that floor and ceiling effects were minimal in this sample. This map allows us to identify raw score ranges for 3 distinct levels of impairment, reflecting the 3 strata that can be distinguished with a person separation of It would be expected that persons in the most impaired stratum would receive scores of 1 or 2 on the 8 easiest items (Echopraxia, Motor Impersistence, Go/No Go, Luria Hand Sequence I, Grip, Thematic Perception, Number Letter and Serial Order Reversal) and scores of 2 on the 6 harder items. Thus, subjects with total raw scores between 21 and 28 would fall in this range and should be rated as severely impaired. Subjects with total raw scores between 0 and 2 would fall in the lowest (least impaired) stratum and should be rated as minimally impaired (ie, it would be expected that those subjects would give an unimpaired performance [score of 0] on all items except the hardest one, Design Fluency, on which they might receive a 0, 1, or 2). Subjects who score in the middle stratum (between 3 and 20) would be rated as moderately impaired. We completed a principal components analysis of the residual information after we extracted the primary measure using Winsteps software. The variance explained by the principal

4 392 RASCH ANALYSIS OF THE EXECUTIVE INTERVIEW (THE EXIT-25), Larson Fig 1. An item map of persons and items. The numbers on the left are Rasch measures in logits. The letter M refers to the mean for persons (left side) or items (right side), S is 1 SD from the mean, and T is 2 SDs from the mean. Each item is shown twice, indicating the transition between the lower and middle rating score category (left column) and the transition point between the middle and upper rating scale category (right column). The horizontal lines drawn at about 2 and 1 logits divide the measure s range into 3, approximately equal levels, corresponding to the 3 strata that can be distinguished with person separation of construct was 84% of the total information. The unexplained variance accounted for by the first residual factor was 2.1%, suggesting that the measure is sufficiently unidimensional. Table 2 shows that an item that places demands on expressive language (Interference) loaded positively on the first factor, whereas items that primarily involve motor response (Luria Hand Sequence II, Go / No Go, Luria Hand Sequence I, Design Fluency) loaded negatively on this factor (values.40 or.40). Correlational analysis revealed strong associations between the EXIT-25 and several neuropsychologic tests; several of the correlations were greater for the 14-item EXIT (see table 1). DISCUSSION A comprehensive literature review showed the reliability and criterion-related validity of the EXIT-25 using classic test theory approaches and supports its use in clinical practice. However, problems with face validity, content validity, and administration time limit its use for patients with acquired brain injury. Rating scale analysis yielded a subset of items, termed The Quick EXIT, that reduces these limitations. Internal consistency and criterion-related validity improved in a sample of stroke and TBI patients. Results provide support for the following 2 hypotheses: (1) the EXIT-25 can be reduced from 25 to 14 items without reducing internal consistency and (2) convergent validity of the Quick EXIT is supported by moderate-size correlations with standard measures of cognitive deficits. A strong correlation with the RBANS Language Index reflects the EXIT s requirement of strong oral expression for many items and the RBANS emphasis on semantic fluency, an ability that is sensitive to the loss of mental organization seen in executive dysfunction. Similarly, the association with RBANS memory indexes is probably a function of effects of executive dysfunction (as measured by the EXIT) on encoding or retrieval of learned

5 RASCH ANALYSIS OF THE EXECUTIVE INTERVIEW (THE EXIT-25), Larson 393 Table 2: Principal Component Analysis of Standardized Residual Correlations for Quick EXIT Items Loading Measure Infit MnSq Item Interference Grip Echopraxia (touch ear) Word fluency Anomalous sentence repetition Motor impersistence Luria hand sequence II Go/no go Luria hand sequence I Design fluency Memory/distraction Number letter Thematic perception Serial order reversal NOTE. Loading refers to each item s loading on the first factor derived from a principal components analysis of the residual information after the latent measure defined by the items is removed. Values.40 or.40 are interpreted as being relatively strong. Measure indicates the logit measure estimate for each item. Infit MnSq refers to the mean-square infit statistic. information (as measured by the memory indexes). The associations with Trails A and B may reflect the EXIT s sensitivity to psychomotor retardation in general and to slowed alphanumeric sequencing in particular. Performance on Trails assesses mental flexibility and self-monitoring, both of which are central to executive functioning as measured by the EXIT. In our stroke sample, almost twice as many people could complete the EXIT as Trails B, which reflects the difficulty that patients with hemiparesis have completing Trails B. The association with the RBANS Attention Index reflects the fact that this index assesses both span of apprehension (assessed by a digit span subtest) and mental efficiency (assessed by a coding task), both of which have substantial impact on executive function. The correlation between the EXIT and the RBANS Visuospatial/ Constructional Index reflects the fact that deficits in visuospatial abilities (especially problems in copying a complex figure, as required by the RBANS) are sometimes secondary to the loss of mental organization measured by the EXIT. The strength of the correlation between the shorter version of the EXIT and other neuropsychologic measures supports the construct validity of the shorter measure. Poor face validity is a problem when patients know the construct being assessed and items appear to be unrelated to the construct. Testing for snout reflex, a grasp reflex and automatic motor behavior, is intrusive and unexpected in patients who are prepared to answer questions, assemble puzzles, and complete paper and pencil measures. In populations who have marked dysregulation of behavior and increased irritability, intrusive or unexpected procedures may result in decreased compliance. Although the Quick EXIT includes a few items with a novel approach to eliciting executive dysfunction, it contains fewer surprises and does not require as much physical manipulation as does the EXIT-25. The content of the Quick EXIT is also more appropriate for patients with neurologic disorders who are typically referred for testing. It addresses questions of mental flexibility and self-monitoring that have more bearing on the need for supervision and other typical reasons for referral than do primitive reflexes (eg, snout reflex) or signs of frontal release (eg, echopraxia and utilization behavior) as assessed by the EXIT-25. Study Limitations Limitations associated with convenience samples should be considered when generalizing these results to the population of adults with acquired neurologic impairment. Our sample was substantially older than most people with TBI, which may impact how the findings would be applied to that population. Although the sample was drawn from inpatient and outpatient settings and reflects a range of cognitive dysfunction, all were drawn from a single system of care. The sample size does not allow us to sensitively evaluate differential item functioning that might distinguish patients with stroke and TBI. Future research with larger samples should evaluate differences in responses between TBI and stroke patients. Future research should also attempt to replicate our findings with a larger and more diverse sample. CONCLUSIONS Time available for testing is increasingly limited in clinical settings. A recent survey of neuropsychologists found that for cases in which a patient is referred for evaluation to assist with treatment planning, the mean time to complete that evaluation is less than 4 hours. 29 When psychologists have brief periods of time in which to assess a variety of cognitive domains, the use of lengthy tests is unrealistic. However, a psychologist must balance the need for efficiency against the ethical requirement to use only measures with adequate reliability and validity, both of which can be compromised when tests are abbreviated. Psychologists attempting to strike this balance should be encouraged by the Quick EXIT s brevity, which is is 44% shorter than the EXIT-25, and its enhanced reliability and construct validity. Further study of the Quick EXIT is needed to support its utility in a broad examination of cognitive abilities that can be used to address common referral questions. A measure of executive function can play a particularly important role in answering referral questions. 30 Similarly, the EXIT-25 can be used in combination with other brief measures (eg, the MMSE) for mental status examinations. 16,18 Further study of the Quick EXIT would clarify whether it can be used to supplement brief screens that are included in initial evaluations performed by physicians and allied health professionals. We thank Laura Wasek, MPH, for her assis- Acknowledgment: tance with editing. References 1. Royall DR, Mahurin RK, Gray KF. Bedside assessment of executive cognitive impairment: the executive interview. J Amer Geriatr Soc 1992;40: Royall DR, Mulroy AR, Chiodo LK, Polk MJ. Clock drawing is sensitive to executive control: a comparison of six methods. J Gerontol B Psychol Sci Soc Sci 1999;54:P Berghuis JP, Uldall KK, Lalonde B. Validity of two scales in identifying HIV-associated dementia. J Acquir Immune Defic Syndr 1999;21: Stokholm J, Vogel A, Gade A, Waldemar G. The executive interview as a screening test for executive dysfunction in patients with mild dementia. J Am Geriatr Soc 2005;53: Gildengers AG, Butters MA, Seligman K, et al. Cognitive functioning in late-life bipolar disorder. Am J Psychiatry 2004;161: Royall DR, Mahurin RK, Cornell J. Bedside assessment of frontal degeneration: distinguishing Alzheimer s disease from non- Alzheimer s cortical dementia. Exp Aging Res 1994;20: Schillerstrom JE, Deuter MS, Wyatt R, Stern SL, Royall DR. Prevalence of executive impairment in patients seen by a psychiatry consultation service. Psychosomatics 2003;4:290-7.

6 394 RASCH ANALYSIS OF THE EXECUTIVE INTERVIEW (THE EXIT-25), Larson 8. Royall DR, Mahurin RK, Cornell J, Gray KF. Bedside assessment of dementia type using the qualitative evaluation of dementia. Neuropsychiatry Neuropsychol Behav Neurol 1993;6: Holzer JC, Gansler DA, Moczynski NP, Folstein MF. Cognitive functions in the informed consent evaluation process: a pilot study. J Am Acad Psychiatry Law 1997;25: Royall DR, Cabello M, Polk MJ. Executive dyscontrol: an important factor affecting the level of care received by older retirees. J Am Geriatr Soc 1998;46: Royall DR, Chiodo LK, Polk MJ. Correlates of disability among elderly retirees with subclinical cognitive impairment. J Gerontol A Biol Med Sci 2000;55:M Royall DR, Chiodo LK, Polk MJ. An empiric approach to level of care determinations: the importance of executive measures. J Gerontol A Biol Med Sci 2005;60: Kelly C, Sharkey V, Morrison G, Allardyce J, McCreadie RG. Nithsdale Schizophrenia Surveys. 20. Cognitive function in a catchment-area-based population of patients with schizophrenia. Br J Psychiatry 2000;177: Quinn J, Meagher D, Murphy P, Kinsella A, Mullaney J, Waddington JL. Vulnerability to involuntary movements over a lifetime trajectory of schizophrenia approaches 100% in association with executive (frontal) dysfunction. Schizophr Res 2001;49: Marin RS, Butters MA, Mulsant BH, Pollock BG, Reynolds CF. Apathy and executive function in depressed elderly. J Geriatr Psychiatry Neurol 2003;16: Larson EB, Leahy B, Duff KM, Wilde MC. Assessing executive functions in traumatic brain injury: an exploratory study of the Executive Interview. Percept Mot Skills 2008;106: Royall DR, Palmer R, Chiodo LK, Polk MJ. Executive control mediates memory s association with change in instrumental activities of daily living: the Freedom House study. J Am Geriatr Soc 2005;53: Royall DR, Mahurin RK, True JE, et al. Executive impairment among the functionally dependent: comparisons between schizophrenic and elderly subjects. Am J Psychiatry 1993;150: Mann LS, Westlake T, Wise TN, Beckman A, Beckman P, Portez D. Executive functioning and compliance in HIV patients. Psychol Rep 1999;84: Stewart JT, Gonzalez-Perez E, Zhu Y, Robinson BE. Cognitive predictors of resistiveness in dementia patients. Am J Geriatr Psychiatry. 1999;7: Royall DR, Palmer R, Chiodo LK, Polk MJ. Declining executive control in normal aging predicts change in functional status: The Freedom House Study. J Am Geriatr Soc. 2004;52: O Shaughnessy JA. Effects of epoetin alfa on cognitive function, mood asthenia, and quality of life in women with breast cancer undergoing adjuvant chemotherapy. Clin Breast Cancer. 2002; Suppl 3:S O Shaughnessy JA, Vukelja SJ, Holmes FA, et al. Feasibility of quantifying the effects of epoetin alfa therapy on cognitive function in women with breast cancer undergoing adjuvant or neoadjuvant chemotherapy. Clin Breast Cancer. 2005;5: Randolph C. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). New York: The Psychological Corporation; War Department, Adjutant General s Office. Army Individual test battery. Washington D.C.: War Department; Rasch G. Probabilistic models for some intelligence and attainment test. Copenhagen: Danmarks Paedogogiske Institut; Wright BD, Masters G. Rating scale analysis: Rasch measurement. Chicago: MESA Press; Linacre JM Optimizing rating scale category effectiveness. J Appl Meas 2002;3: Sweet JJ, Nelson NW, Moberg PJ. The TCN/AACN 2005 Salary Survey : professional practices, beliefs, and incomes of U.S. neuropsychologists. Clin Neuropsychol. 2006;20: Hanks RA, Rapport LJ, Millis SR, Desphande SA. Measures of executive function as predictors of functional ability and social integration in a rehabilitation sample. Arch Phys Med Rehabil 1999;80: Suppliers a. Winsteps; Available at: b. SPSS Inc, 233 S Wacker Dr, 11th Fl, Chicago, IL