Biomedical subjects

Kevin Duff

Publications and source records attributed to Kevin Duff.

At least 19 recordsLinked to original sources

PubMed2007

Neuropsychological and psychiatric functioning pre- and posthematopoietic stem cell transplantation in adult cancer patients: a preliminary study.

The current study characterizes cognitive and psychiatric status in hematopoietic stem cell transplantation (HSCT) patients shortly before and after transplant. Thirty adult patients were assessed prospectively 1-2 weeks before transplantation and 100 days posttransplantation on neuropsychological and psychiatric measures. Before transplant, participants showed mild impairments on several neuropsychological measures, with the poorest performances occurring on learning and attention. Psychiatric functioning was significantly elevated compared with normative data. Significant improvements, however, were observed on neuropsychological measures by 100 days after transplant. Depression and anxiety scores also improved. Candidates for HSCT experienced mild diffuse cognitive dysfunction and psychiatric morbidity before the procedure, but these symptoms significantly improved by 3 months following their transplant in this small sample. Education about these possible pretransplant sequelae and the potential for rebound may be helpful to patients and families as they prepare for this treatment and the recovery period.

Adult↗

PubMed2006

Presentation of Alzheimer's disease in patients with and without olfactory deficits.

Odor identification deficits are frequently reported in Alzheimer's disease (AD) but are not universal. This study examines differences in clinical presentation in AD patients with and without odor identification impairments. Ninety patients with probable AD were administered an odor identification test as part of a neuropsychological evaluation. Variables examined included demographic information, cognitive and behavioral measures, dementia severity, neuroimaging findings, and aspects of clinical history. Defining the groups with a median split, olfactory impaired and olfactory intact patients were mostly similar, though patients with impaired odor identification performance were more likely to be male, less likely to have a family history of dementia, and had worse visuospatial functioning. The differences noted raise the possibility of a clinical subtype of the disease.

Aged↗

PubMed2006

Practice effects in the prediction of long-term cognitive outcome in three patient samples: a novel prognostic index.

Practice effects, defined as improvements in cognitive test performance due to repeated exposure to the test materials, have traditionally been viewed as sources of error. However, they might provide useful information for predicting cognitive outcome. The current study used three separate patient samples (older adults with mild cognitive impairments, individuals who were HIV+, individuals with Huntington's disease) to examine the relationship between practice effects and cognitive functioning at a later point. Across all three samples, practice effects accounted for as much as 31-83% of the variance in the follow-up cognitive scores, after controlling for baseline cognitive functioning. If these findings can be replicated in other patients with neurodegenerative disorders, clinicians and researchers may be able to develop predictive models to identify the individuals who are most likely to demonstrate continued cognitive decline across time. The ability to utilize practice effects data would add a simple, convenient, and non-invasive marker for monitoring an individual patient's cognitive status. Additionally, this prognostic index could be used to offer interventions to patients who are in the earliest stages of progressive neurodegenerative disorders.

Adult↗

PubMed2006

Test performance and classification statistics for the Rey Auditory Verbal Learning Test in selected clinical samples.

The Rey Auditory Verbal Learning Test [RAVLT; Rey, A. (1941). L'examen psychologique dans les cas d'encéphalopathie traumatique. Archives de Psychologie, 28, 21] is a commonly used neuropsychological measure that assesses verbal learning and memory. Normative data have been compiled [Schmidt, M. (1996). Rey Auditory and Verbal Learning Test: A handbook. Los Angeles, CA: Western Psychological Services]. When assessing an individual suspected of neurological dysfunction, useful comparisons include the extent that the patient deviates from healthy peers and also how closely the subject's performance matches those with known brain injury. This study provides the means and S.D.'s of 392 individuals with documented neurological dysfunction [closed head TBI (n=68), neoplasms (n=57), stroke (n=47), Dementia of the Alzheimer's type (n=158), and presurgical epilepsy left seizure focus (n=28), presurgical epilepsy right seizure focus (n=34)] and 122 patients with no known neurological dysfunction and psychiatric complaints. Patients were stratified into three age groups, 16-35, 36-59, and 60-88. Data were provided for trials I-V, List B, immediate recall, 30-min delayed recall, and recognition. Classification characteristics of the RAVLT using [Schmidt, M. (1996). Rey Auditory and Verbal Learning Test: A handbook. Los Angeles, CA: Western Psychological Services] meta-norms found the RAVLT to best distinguish patients suspected of Alzheimer's disease from the psychiatric comparison group.

Adolescent↗

PubMed2006

Prediction errors of the Oklahoma Premorbid Intelligence Estimate-3 (OPIE-3) stratified by 13 age groups.

The Oklahoma Premorbid Intelligence Estimate-3 (OPIE-3) combines Wechsler Adult Intelligence Scale-3rd edition (WAIS-III) subtest raw scores (vocabulary, information, matrix reasoning, and picture completion) and demographic data (i.e., age, education, gender, ethnicity, and region) to predict FSIQ scores. Differences between OPIE-3 estimated FSIQ scores and actual FSIQ scores were compared across 13 age groups in a random sample (N=1201) of the WAIS-III standardization sample. There were mean differences in estimated FSIQ between age groups (P<.01). There was a trend that the OPIE-3 algorithms underestimated FSIQ for individuals 16-17 (2.7 points) and 80-89 years old (3.5 points). However, the differences in estimation errors were small and the percentage of individuals misclassified by more than 10 FSIQ points by age group was similar across groups. The OPIE-3(2ST), OPIE-3MR, and OPIE-3VOC yielded robust estimates of FSIQ across age groups in a neurologically intact sample. Limitations, particularly with individuals aged 16-17 and 85-89 years, are discussed.

Adolescent↗

PubMed2006

Probability of obsessive and compulsive symptoms in Huntington's disease.

BACKGROUND: The purpose of this study was to examine the probability of obsessive and compulsive (OC) symptoms across stages of Huntington's disease (HD) with both cross sectional and longitudinal data. METHODS: We present the largest sample to date of individuals at risk for HD (N = 3964). Obsessive and compulsive symptoms were assessed with the Unified Huntington's Disease Rating Scale OC items. RESULTS: The probability of meeting the threshold for obsessions and compulsions increased with greater disease severity. Those with no motor abnormalities ("at risk") had a 7% probability of obsessions and a 3.5% probability of compulsions; the peak probability for obsessions (24%) and compulsions (12%) occurred in patients with advanced disease with significant functional disability. CONCLUSIONS: The probability of OC symptoms is more than three times greater by stages 3 and 4 (clearly manifest disease) than in our at-risk group with no apparent motor abnormalities.

Adult↗

PubMed2006

Incidence of delirium and associated mortality in hematopoietic stem cell transplantation patients.

Delirium has been associated with a high risk of mortality in medical patients. Despite the high incidence of delirium in patients who undergo hemapoietic stem cell transplantation (HSCT), delirium as a risk factor for death has not been examined in this population. Thirty adult patients undergoing HSCT who were admitted to the University of Iowa Blood and Marrow Transplantation Program inpatient unit were assessed prospectively from 1 to 2 weeks before transplantation, throughout their inpatient stay, and at 100 days after transplantation. The Delirium Rating Scale and Memorial Delirium Assessment Scale were used twice weekly during the inpatient period to assess delirium severity and occurence. Patients' self-reports of medical history, computerized medical records, and neuropsychological and psychiatric assessments were used to identify pretransplantation risk factors. The incidence of delirium (Delirium Rating Scale score >12 or Memorial Delirium Assessment Scale score >or=8) was 43% and occurred with highest frequency in the first 2 weeks after transplantion. The presence of delirium at any point during hospitalization after transplantation and transplant type (allogeneic) were highly predictive of mortality (p < .0005; odds ratios, 14.0 and 14.4). In conclusion, this study highlights the importance of monitoring for delirium during the acute recovery period after transplantation and suggests that early or even prophylactic treatment for delirium should be studied. Studies to determine the factors that connect delerium soon after transplantation to mortality are highly warranted.

Adolescent↗

PubMed2006

Examining the repeatable battery for the assessment of neuropsychological status: factor analytic studies in an elderly sample.

OBJECTIVE: The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), a recently developed cognitive assessment instrument, has been shown to be useful with a variety of neuropsychiatric conditions, but its factor structure has not been examined. METHOD: Using 824 community-dwelling elders, the RBANS was examined with confirmatory and exploratory factor analyses. RESULTS: The existing structure of the RBANS was not supported; however, a two-factor solution was. CONCLUSIONS: Clinicians and researchers using the RBANS should be cautious when interpreting this measure with its existing structure.

Aged↗

PubMed2006

Donepezil effects on cerebral blood flow in older adults with mild cognitive deficits.

Cerebral blood flow (CBF) was assessed during a verbal recall task using [(15)O]water positron emission tomography (PET) in older adults with mild cognitive deficits participating in a placebo-controlled donepezil trial. The placebo group demonstrated reduced CBF in the left frontal and temporal regions over the 6-month period, while those receiving donepezil did not. The placebo group's performance did not change on a list-learning task, while the donepezil group's performance improved, despite having had lower performance at intake. These findings suggest that donepezil treatment may be associated with a relative maintenance of CBF and improved list-learning.

Activities of Daily Living↗

PubMed2005

RBANS index discrepancies: base rates for older adults.

The present study expands upon the data available in the manual of the Repeatable Battery for the Assessment of Neuropsychological Status, by providing base rate data on Index discrepancies that are organized by general level of ability and include both age and education corrections. The data presented are based on the performances of a sample of 718 community dwelling older adults. These findings offer the possibility of increased sensitivity at detecting clinically significant differences that might not be identified when relying on base rate data from a greater age range. Similarly, these data highlight the mediating effects of the global level of cognitive functioning on discrepancy scores.

Aged↗

PubMed2005

The relationship between executive functioning and verbal and visual learning and memory.

Executive functions, which include an individual's ability to develop a response set, inhibit behaviors, plan, and reason, likely impact other areas of cognitive functioning, such as learning and memory. The present study examined the relationship between executive functioning and a wide array of standardized, clinical verbal and visual learning and memory measures in 212 patients referred for a neuropsychological evaluation. IQ was also included in the analyses. Results of the canonical correlation analyses indicated that the two cognitive domains shared 55-60% of variance, and two canonical variates were present. Although causality cannot be inferred, a clear and robust relationship between executive functioning and memory is evident, and clinicians should consider this overlap when interpreting poor performance among these two domains.

Adolescent↗

PubMed2005

Regression-based formulas for predicting change in RBANS subtests with older adults.

Repeated neuropsychological assessments are common with older adults, and the determination of clinically significant change across time is an important issue. Regression-based prediction formulas have been utilized with other patient and healthy control samples to predict follow-up test performance based on initial performance and demographic variables. Comparisons between predicted and observed follow-up performances can assist clinicians in making the determination of change in the individual patient. The current study developed regression-based prediction equations for the twelve subtests of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) in a sample of 223 community dwelling older adults. All algorithms included both initial test performances and demographic variables. These algorithms were then validated on a separate elderly sample (n = 222). Minimal differences were present between Observed and Predicted follow-up scores in the Validation sample, suggesting that the prediction formulas would be useful for practitioners who assess older adults. A case example is presented that utilizes the formulas.

Age Factors↗

PubMed2005

Practice effects and the use of alternate forms in serial neuropsychological testing.

Accurate understanding of practice characteristics, performance stability, and error on neuropsychological tests is essential to both valid clinical assessment and maximization of signal detection for clinical trials of cognitive enhancing drugs. We examined practice effects in 28 healthy adults. As part of a larger study using donepezil and simulating a Phase I trial, participants were randomized into: placebo, no-treatment and donepezil. Donepezil results are presented elsewhere. Neuropsychological tests were administered in a fixed order for 6 weeks, with alternate forms available for most tests. Despite alternate forms, ANOVAs revealed significant improvements for the pooled control group (placebo and no-treatment) on all tests except Letter Number Sequencing and Trails B. Learning occurred principally in the first three to four sessions. PASAT and Stroop interference showed the greatest learning. Thus, serial assessment with alternate forms may attenuate retest effects on some tests, but continued learning occurs on novel tests or those in which an advantageous test-taking strategy can be identified. Alternate forms and baseline practice sessions may help control early, rapid improvements in clinical trials.

Adult↗

PubMed2005

Test-retest stability and practice effects of the RBANS in a community dwelling elderly sample.

Repeated neuropsychological assessments are common with older adults, and the determination of true neurocognitive change is important for diagnostic assessment. Several statistical formulas are available to assist in this determination, but they rely on access to test-retest stability coefficients and practice effect values. The current study presents data on these psychometric properties of the RBANS in a large community dwelling elderly sample. Across a one-year retest interval, stability coefficients ranged from .58 to .83 for the Index scores, and from .51 to .83 for the subtest scores. Practice effects were largely absent, with most performances slightly decreasing at retest. These psychometric properties are contrasted with those reported in the RBANS manual, and possible reasons for these differences are discussed. A case example is provided that demonstrates the use of the current findings in conjunction with existing change formulas.

Aged↗

PubMed2005

Base rates of longitudinal RBANS discrepancies at one- and two-year intervals in community-dwelling older adults.

Identification of clinically significant change in performance over time on neurocognitive tests is an important aspect of neuropsychological evaluation; however, scant published empirical data exists to guide the clinician in determining the significance of psychometric change across clinically relevant retest intervals. The present study presents base rate data of RBANS score discrepancies in a user-friendly manner based on the performances of a large sample (n=283) of community-dwelling older adults. Data for 1- and 2-year retest intervals are presented in a tabular form that can be used as a convenient reference. Base rates of discrepancy scores were calculated and organized into three groups (i.e., below average, average, and above average) with respect to the participants' OKLAHOMA age- and education-corrected RBANS Total Scale score (Duff, Patton, Schoenberg, Mold, Scott, & Adams, 2003) at initial assessment, in an effort to reduce the influence of regression to the mean and practice effects that is associated with varying levels of cognitive ability. (e.g., Rapport, Axelrod, Theisen, Brines, Kalechstein, & Ricker, 1997; Rapport, Brines, Axelrod, & Theisen, 1997). These data may be helpful in clinical practice by assisting the clinician in determining the clinical significance of score changes.

Age Factors↗

PubMed2005

White matter volume and cognitive dysfunction in early Huntington's disease.

BACKGROUND: Structural abnormalities of the striatum and cognitive impairments have consistently been shown in patients with Huntington's disease (HD). Fewer studies have examined other cerebral structures in early HD and potential associations with cognition. METHOD: Ten patients with early HD and 10 matched control subjects underwent magnetic resonance imaging to provide quantitative measures (volumes) of cortical gray and white matter and the caudate, putamen, and thalamus. Patients completed the Unified Huntington's Disease Rating Scale, including three cognitive tasks. RESULTS: Although striatal volumes were clearly reduced, white matter was also morphologically abnormal. Cortical gray matter volume was not significantly correlated with cognitive performance. However, the cognitive tasks were most highly correlated with cerebral white matter and, to a lesser degree, striatal volume. CONCLUSIONS: Cerebral white matter volume may be an important variable to examine in future studies of HD.

Adult↗

PubMed2005

Performance of community-dwelling adults ages 55 to 75 on the University of Pennsylvania smell identification test: an item analysis.

Tests of odor identification, such as the University of Pennsylvania Smell Identification Test (UPSIT; Doty, 1995), are used in both research and clinical settings to assess the individual's sense of smell. Although previous studies have evaluated the psychometric properties of the UPSIT, little research has been conducted explicitly with unimpaired adults. This study evaluated the results of the UPSIT for 197 community-dwelling adults between the ages of 55 and 75. An item analysis identified six items that had poor hit rates in this sample. Implications of these results are discussed.

Aged↗

PubMed2004

Performance profiles and cut-off scores on the Memory Assessment Scales.

The increased role of neuropsychologists in the courtroom has led to an increased effort in the detection of possible symptom exaggeration/malingering. Whereas domain specific measures of malingering have traditionally been used in this detection process, the identification of performance profiles and cut-off scores on standard neuropsychological assessment instruments may provide an alternate strategy. The present study evaluated the effectiveness of performance profiles and cut-off scores in discriminating traumatic brain injury (TBI) litigants suspected of malingering from those not suspected of malingering on the Memory Assessment Scales (MAS). Results suggest that TBI litigants suspected of poor effort will perform globally at a lower level than TBI litigants not suspected of poor effort on nearly all MAS indices, however, the performance profiles of each group was similar. Cut-off scores, especially when used in combination, were also effective in correctly classifying individuals in the two groups. The present findings warrant further research examining the utility of the proposed cut-off scores separately and concomitantly. Such research will aid the clinical neuropsychological practitioner in interpreting aberrant performance profiles on the MAS in forensic situations.

Adult↗