Biomedical subjects

Glenn Curtiss

Publications and source records attributed to Glenn Curtiss.

15 recordsLinked to original sources

PubMed2006

Executive control and learning pattern on the CVLT.

We evaluated a 23 year-old man after recovery from encephalitis. In contrast to the expected pattern of increasingly better acquisition across the 5 learning trials of the California Verbal Learning Test (CVLT-2), he produced a "J-shaped" curve (Trials 1-5: 8,6,6,9,11). Because he also demonstrated excessive levels of proactive interference as well as poor divided attention, we hypothesized that his atypical learning pattern was due to a build-up of proactive interference secondary to executive dyscontrol. Using a large sample of 4462 healthy adult men, we identified four groups exhibiting various learning patterns. We found that a learning pattern similar to this patient (i.e., a drop after trial 1 followed by recovery) was rare (1.1% of the sample). Individuals with this learning pattern demonstrated increased perseverative responses, as well as greater difficulty maintaining cognitive set on the Wisconsin Card Sorting Test, decreased attentional control on the Paced Auditory Serial Addition Test, and greater levels of proactive interference on the CVLT. Taken together, the results of the study suggest that an early drop, followed by a recovery in learning trial performance, is associated with executive dyscontrol.

Adult↗

PubMed2005

Headache after moderate and severe traumatic brain injury: a longitudinal analysis.

OBJECTIVES: To measure longitudinally headache (HA) after moderate and severe traumatic brain injury (TBI) and to examine potential association with demographic, injury, and psychologic factors. DESIGN: Cohort study. SETTING: Four Veterans Administration rehabilitation facilities (Minneapolis, Palo Alto, Richmond, Tampa) within the Defense and Veterans Brain Injury Center. PARTICIPANTS: Consecutive patients (military or veteran beneficiaries) with moderate or severe TBI (N=109) who during acute rehabilitation consented to data collection and who completed 6- and 12-month follow-up evaluations. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: HA frequency, location, type, and incapacitation levels measured during prospective neurologic assessments. RESULTS: Nearly 38% (41/109) of patients had acute posttraumatic headache (PTHA) symptoms; most often in a frontal location (20/41), most often of daily frequency (31/41), and showing no relation to injury severity, emotional, or demographic variables. Postacutely, PTHA symptom severity declined within the group. Better individual improvement was associated with less anxiety and depression at 6-month follow-up. Almost all subjects (21/22) with PTHA symptoms that persisted into the 6-month follow-up period reported symptoms again at 12-month follow-up. CONCLUSIONS: PTHA severity in this sample of persons with moderate and severe TBI showed a pattern of improvement that leveled off by 6 months posthospitalization.

Adolescent↗

PubMed2005

Factors moderating neuropsychological outcomes following mild traumatic brain injury: a meta-analysis.

There continues to be debate about the long-term neuropsychological impact of mild traumatic brain injury (MTBI). A meta-analysis of the relevant literature was conducted to determine the impact of MTBI across nine cognitive domains. The analysis was based on 39 studies involving 1463 cases of MTBI and 1191 control cases. The overall effect of MTBI on neuropsychological functioning was moderate (d = .54). However, findings were moderated by cognitive domain, time since injury, patient characteristics, and sampling methods. Acute effects (less than 3 months postinjury) of MTBI were greatest for delayed memory and fluency (d = 1.03 and .89, respectively). In unselected or prospective samples, the overall analysis revealed no residual neuropsychological impairment by 3 months postinjury (d = .04). In contrast, clinic-based samples and samples including participants in litigation were associated with greater cognitive sequelae of MTBI (d = .74 and .78, respectively at 3 months or greater). Indeed, litigation was associated with stable or worsening of cognitive functioning over time. The implications and limitations of these findings are discussed.

Brain Injuries↗

PubMed2005

Long-term neuropsychological outcomes following mild traumatic brain injury.

Mild traumatic brain injury (MTBI) is common, yet few studies have examined neuropsychological outcomes more than 1 year postinjury. Studies of nonreferred individuals with MTBI or studies with appropriate control groups are lacking, but necessary to draw conclusions regarding natural recovery from MTBI. We examined the long-term neuropsychological outcomes of a self-reported MTBI an average of 8 years postinjury in a nonreferred community-dwelling sample of male veterans. This was a cross-sectional cohort study derived from the Vietnam Experience Study. Three groups matched on premorbid cognitive ability were examined, those who (1) had not been injured in a MVA nor had a head injury (Normal Control; n = 3214), (2) had been injured in a motor vehicle accident (MVA) but did not have a head injury (MVA Control; n = 539), and (3) had a head injury with altered consciousness (MTBI; n = 254). A MANOVA found no group differences on a standard neuropsychological test battery of 15 measures. Across 15 measures, the average neuropsychological effect size of MTBI compared with either control group was -.03. Subtle aspects of attention and working memory also were examined by comparing groups on Paced Auditory Serial Addition Test (PASAT) continuation rate and California Verbal Learning Test (CVLT) proactive interference (PI). Compared with normal controls, the MTBI group evidenced attention problems in their lower rate of continuation to completion on the PASAT (odds ratio = 1.32, CI = 1.0-1.73) and in excessive PI (odds ratio = 1.66, CI = 1.11-2.47). Unique to the MTBI group, PASAT continuation problems were associated with left-sided visual imperceptions and excessive PI was associated with impaired tandem gait. These results show that MTBI can have adverse long-term neuropsychological outcomes on subtle aspects of complex attention and working memory.

Adult↗

PubMed2005

Role of executive functioning in verbal and visual memory.

G. Tremont, S. Halpert, D. J. Javorsky, and R. A. Stern (2000) found that individuals with executive dysfunction were more impaired on less structured versus more structured verbal memory tasks. In the present study, the authors investigated the relationship between executive functions and memory in patients with a history of traumatic brain injury by examining the effect of executive functioning on more structured and less structured verbal and visual memory tasks at baseline and 1-year follow-up. Matched subgroups controlled for differences in severity of neuropsychological impairment unrelated to specific executive functions. The G. Tremont et al. (2000) findings were not replicated. Results showed that when acuteness and severity of injury were controlled, executive impairment played no significant role in performance on either more or less structured memory tasks. However, regardless of structure, executive functions played a role in visual memory performance, suggesting that visual memory may be a more fluid ability than verbal memory.

Adolescent↗

PubMed2005

The components of executive functioning in traumatic brain injury.

Theorists have proposed models of executive functioning, and functional neuroimaging and factor analytic studies have attempted to examine the components of executive functioning. These studies have arrived at different conclusions and many empirical studies are wrought with methodological confounds. The purpose of this exploratory study was to investigate the subcomponents of executive abilities while addressing some of the limitations common in previous studies. Neuropsychological test data were obtained from a sample of individuals with a history of TBI seen at one-year follow-up (n=104). Principal components factor analysis was conducted and yielded three factors that accounted for 52.7% of the variance. The first factor included higher-order executive functions with two components: self-generative behavior and cognitive flexibility/set shifting. The second factor appeared to represent mental control, particularly of ongoing working memory. The third factor consisted of memory errors, representing failure to inhibit reporting of inaccurate information. Although the results are not entirely consistent with any of the current theoretical models of executive function, they appear to be most consistent with the 1986 model of Stuss and Benson.

Adult↗

PubMed2003

Predictors of postconcussion symptom complex in community dwelling male veterans.

The presence of a persistent postconcussion symptom complex (PPCSC) was examined in a non-referred sample of male veterans with a history of mild head injury and a comparison group without a history of head injury. Hierarchical logistic regression procedures were used to determine possible predictors of PPCSC using variables supported by previous research (i.e., preexisting psychiatric difficulties, demographic and social support variables, and history of an accidental injurious event). Although PPCSC was common in all groups (23% of the total sample), a significantly greater proportion of individuals in the mild head injury with loss of consciousness group (37.2%) had PPCSC compared with three other groups (head injury without loss of consciousness = 26.1%; motor vehicle accident without head injury = 23%; and control = 17.3%). However, the most salient predictors of PPCSC were early life psychiatric difficulties such as anxiety or depression, limited social support, lower intelligence, and interactions among these variables. The predictive value of loss of consciousness was significant, but low (1.4% of unique variance). The findings provide support for the premise that PPCSC is mediated in part by individual resilience, preexisting psychological status, and psychosocial support.

Accidents, Traffic↗

PubMed2003

Development of the Key Behaviors Change Inventory: a traumatic brain injury behavioral outcome assessment instrument.

OBJECTIVE: To describe the development and initial validation of a neurobehavioral outcome measure, the Key Behaviors Change Inventory (KBCI), for individuals with traumatic brain injury (TBI). DESIGN: Scale construction and development, and validity study. SETTING: Large state university and postal survey. PARTICIPANTS: Seventy-five volunteer undergraduate students and 25 volunteer collateral informants of individuals with TBI participated in the item-analysis phase. Thirty members of the Brain Injury Association and 20 members of the National Multiple Sclerosis Society rated both an identified patient and an age- and gender-equated control in the validation phase. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Content validity was examined through expert panel item sorts. Scale internal consistencies were examined with the Cronbach alpha. Construct validity was examined by comparing scale elevations between controls and 2 neurologic groups. RESULTS: Item-analysis procedures resulted in 8 scales of 8 items each: inattention, impulsivity, unawareness of problems, apathy, interpersonal difficulties, communication problems, somatic difficulties, and emotional adjustment. Internal consistency reliability coefficients ranged from.82 to.91. Multivariate analysis of variance revealed significant (P</=.001) differences in scale elevations among TBI, multiple sclerosis (MS), and control groups. The TBI and MS groups scored significantly higher than the control group on all scales; a subset of KBCI scales discriminated between the 2 neurologic groups. CONCLUSION: The KBCI was both sensitive and specific to typical behavioral changes after TBI, thus supporting its usefulness in rehabilitation settings. Cross-validation and development of a normative database are future steps necessary in its development.

Adaptation, Psychological↗

PubMed2003

WAIS-III processing speed index scores after TBI: the influence of working memory, psychomotor speed and perceptual processing.

This study investigates the extent to which working memory, motor speed and perceptual processing speed influence Wechsler Adult Intelligence Scale-III (WAIS-III) Processing Speed Index (PSI) scores. Sixty-eight adult outpatients with Traumatic Brain Injury (TBI) of varying severity and complete data on all outcome measures were identified. Two cases with outlying values on one outcome measure were omitted from the final sample. Working memory was measured by the Working Memory Index score from the WAIS-III. Motor speed was measured as score on the Halstead-Reitan Finger Oscillation Test (finger tapping) and perceptual processing as score on the Trail Making Test--Part B. In hierarchical multiple regression analyses, working memory accounted for 10% of the variance in PSI scores, whereas motor speed only accounted for 3%. An independent measure of perceptual processing, Trail Making Test--B, accounted for 26% of the variance in WAIS-III PSI scores. The total variance accounted for by the three factors was 56%. Findings confirm that the WAIS-III PSI scores of individuals who have received a TBI reflect perceptual processing speed, with an additional component attributable to working memory. Motor speed made only a small contribution to WAIS-III PSI scores in the present sample.

Adolescent↗

PubMed2002

The Key Behaviors Change Inventory and executive functioning in an elderly clinic sample.

The Key Behaviors Change Inventory (KBCI) was developed to assess executive, behavioral, and emotional functioning following brain insults and to track the course of recovery. The purpose of this study was to investigate, in an elderly memory disorder clinic sample, the convergent and discriminant validity of the KBCI by examining the relationships between various measures of executive functioning and the KBCI scales that theoretically relate to executive functions. The KBCI was administered to the caregivers of 97 consecutive patients who came to a memory disorders clinic seeking services. The KBCI scales of Inattention, Apathy, Unawareness of Problems, and Communication Problems were significantly correlated with cognitive measures of executive functioning but not with measures of memory, visuospatial abilities or global cognitive functioning. In contrast, KBCI scales of Interpersonal Difficulties, Somatic Difficulties, and Emotional Adjustment were not related to any cognitive measures, either executive or nonexecutive. Contrary to predicted findings, the Impulsivity Scale was not associated with cognitive measures of executive functioning. This lack of relationship most likely reflects the failure to include executive measures of orbitofrontal functioning in this study. Results provide convergent and discriminant validity support for the KBCI. The KBCI may be a useful tool for assessing and tracking the executive, behavioral, and emotional sequelae of neurologic disorders.

Adaptation, Psychological↗

PubMed2002

Validity indicators within the Wisconsin Card Sorting Test: application of new and previously researched multivariate procedures in multiple traumatic brain injury samples.

The Wisconsin Card Sorting Test (WCST) is a popular neuropsychological measure of executive dysfunction that has been researched with regard to invalid performances, a subset of which in a forensic context could be associated with malingering. In the first of three studies, WCST multivariate approaches identified in prior research (Bernard, McGrath, & Houston, 1996; Suhr & Boyer, 1999), as well as newly created variables, were used to differentiate 33 chronic traumatic brain injury (TBI) patients with good effort and 27 patients with probable insufficient effort (IE). Newly created variables that were derived logically based upon hypotheses regarding strategies that might be employed by malingerers were not effective in differentiating TBI and IE groups. Application of previously researched validity indicators based upon commonly used WCST variables, individually, and within new logistic regression findings were reasonably effective in differentiating TBI and IE groups. In order to determine whether results would vary in different TBI samples, these validity indicators were examined in Study 2 with 75 moderate and severe, acute TBI rehabilitation patients whose posttraumatic amnesia had just resolved. Statistically significant differences were present between the IE group of Study 1 and the rehabilitation patient group of Study 2 on failures to maintain set, number of trials to achieve first correct category, and number of categories completed. All these measures were performed more poorly by the IE group. However, previously used multivariate approaches and the logistic regression analysis developed in Study 1 ranged widely in the degree to which Study 2's more acute rehabilitation patients were correctly classified. Specifically, the discriminant function of Bernard and colleagues correctly classified 73% and the Suhr and Boyer logistic regression correctly classified 75% of the Study 2 participants. The Study 1 logistic regression classified 97% of the Study 2 participants correctly. In Study 3, 130 mild to severe TBI patients in the VA system were studied. The Study 1 IE group performed significantly worse than the more acute and more severe VA TBI group on all 10 common WCST variables of interest. Application of the three multivariate procedures resulted in good to excellent classification rates: Suhr and Boyer logistic regression 85%, Bernard et al. discriminant function 85%, and Study 1 logistic regression 99%. The aggregate discussion of the three studies focuses on apparent differences in samples associated with varying degrees of success in identifying TBI patients. Application of these validity indicators in forensic situations should consider that some of these multivariate approaches possess possible classification limitations associated with chronicity and severity of the reported TBI. Only the Study 1 logistic regression demonstrated improved classification rates with the more acute and severe patients of Study 2 and Study 3. As with all validity indicators, use of any WCST IE criteria in isolation would not be appropriate.

Adult↗

PubMed2002

Identifying retrieval problems using the California Verbal Learning Test.

Wilde, Boake, and Sherer (1995) examined the discrepancy between Long Delayed Free Recall (LDFR) and Recognition Discriminability (RD)--the California Verbal Learning Test (CVLT) index thought to indicate the presence of memory retrieval problems--and found little evidence to recommend its use in traumatic brain injury (TBI). The present investigation re-examined this index from the perspective of a continuum of retrieval deficit severity. CVLT performance was examined in 122 TBI patients, and 2 retrieval deficit indicators of varying severity were evaluated. Memory-impaired control groups were matched with retrieval deficit groups on initial acquisition and demographic characteristics. Individuals with a LDFR/RD discrepancy did not show predicted differences on other CVLT indices of retrieval problems, similar to the findings of Wilde et al. (1995). In contrast, individuals with a consistent discrepancy between free recall and semantic cued recall (Short and Long Delay) had greater improvement with recognition cueing and made fewer intrusive errors than controls. Individuals who benefited from semantic cues (where retrieval of the target word is still required) also benefited from recognition cues (where retrieval demands are minimal). Evidence supported the existence of a continuum of retrieval deficit severity. An LDFR/RD discrepancy without performance improvement from semantic cueing appears to indicate a more severe retrieval deficit, whereas performance improvement from both recognition and semantic cueing indicates less severe retrieval deficits.

Adult↗

PubMed2002

The effects of depression and anxiety on memory performance.

The effects of depression and anxiety, as assessed by MMPI D and Pt scales, on memory performance was examined in 3999 veterans who completed the California Verbal Learning Test (CVLT). Depressive symptoms (without anxiety) had an adverse effect on immediate recall of new information and the total amount (but not rate) of acquisition; however, retrieval and retention were unaffected. On the other hand, high levels of anxiety did not have significant detrimental effects on any aspect of memory functioning assessed including immediate recall, total amount acquired, retention, and retrieval of novel information. However, when depression was compounded by anxiety, there was not only an adverse effect on immediate recall and amount (but not rate) of acquisition, but also on the retrieval of newly learned information. We conclude that the presence of comorbid anxiety may, in part, account for the variability in previous research findings regarding the effects of depression on memory functioning.

Journal Article↗

PubMedDate not supplied

Demographic, medical, and psychiatric factors in work and marital status after mild head injury.

OBJECTIVE: To explore factors associated with long-term outcomes of work and marital status in individuals who had experienced a mild head injury (MHI), as well as those who had not. DESIGN: Population-based study using logistical regression analyses to investigate the impact of preinjury characteristics on work and marital status. PARTICIPANTS: Two groups of Vietnam-era Army veterans: 626 who had experienced a MHI an average of 8 years before examination, and 3,896 who had not. MAIN OUTCOME MEASURES: Demographic characteristics, concurrent medical conditions, early life psychiatric problems, loss of consciousness (LOC), and interactions among these variables were used to predict current work and marital status. RESULTS: Multiple variables were associated with work and marital status in the sample with MHI, accounting for approximately 23% and 17% of the variance in these two outcome variables, respectively. In contrast, the same factors accounted for significantly less variance in outcome in the sample without a head injury-13.3% and 9.4% for work and marital status, respectively. CONCLUSIONS: These findings suggest a more potent role for and increased vulnerability to the influence of demographic, medical, and psychiatric factors on outcomes after a MHI. That is, MHI itself moderates the influence of preinjury characteristics on work and marital status. In addition, in those who had a MHI, moderator relationships were found between education and LOC for both work and marital status. Similarly, complex moderator relationships among race, region of residence, and LOC were found for both work and marital status outcomes.

Adult↗

PubMedDate not supplied

Utility of mechanism-of-injury-based assessment and treatment: Blast Injury Program case illustration.

While medicine typically proceeds in a sequential fashion based on primary symptoms, sometimes relying on a parallel, mechanism-of-injury-based approach is advantageous, particularly when the mechanism of injury is associated with a variety of known sequelae. A mechanism-of-injury-based approach relies on knowledge of the typical sequelae associated with that mechanism of injury to guide assessment and treatment. Thus, it represents an active, rather than passive, case-finding approach. This article describes an example of a mechanism-of-injury-based program, namely, a Blast Injury Program at the James A. Haley Veterans Hospital in Tampa, Florida. Case examples illustrate the utility of this approach with regard to more comprehensive assessment and treatment, as well as the possibility for secondary prevention.

Adult↗