Biomedical subjects

Grant L Iverson

Publications and source records attributed to Grant L Iverson.

At least 19 recordsLinked to original sources

PubMed2006

Misdiagnosis of the persistent postconcussion syndrome in patients with depression.

The purpose of this study is to examine the prevalence of postconcussion-like symptoms in patients with depression. Participants were 64 physician-diagnosed inpatients or outpatients with depression who had independently-confirmed diagnoses on the Structured Clinical Interview for DSM-IV. All completed the British Columbia Postconcussion Symptom Inventory, a 16-item measure designed to assess the frequency and severity of symptoms based on ICD-10 criteria for postconcussion syndrome. Specific endorsement rates of postconcussion-like symptoms ranged from 31.2% to 85.6% for symptoms rated mild or greater, and from 10.9% to 57.8% for symptoms rated moderate-to-severe. Approximately 9 out of 10 patients with depression met liberal self-report criteria for a postconcussion syndrome and more than 5 out of 10 met conservative criteria for the diagnosis. Implications for forensic neuropsychology will be discussed.

Adult↗

PubMed2006

Tracking neuropsychological recovery following concussion in sport.

PRIMARY OBJECTIVE: The purpose of this study was to illustrate the serial use of computerized neuropsychological screening with ImPACT to monitor recovery in a clinical case series of injured athletes. METHODS AND PROCEDURES: Amateur athletes with concussions (n= 30, average age= 16.1, SD= 2.1 years) underwent pre-season testing and three post-concussion evaluations within the following intervals: 1-2 days, 3-7 days (M= 5.2 days) and 1-3 weeks (M= 10.3 days). The study selection criteria increased the probability of including athletes with slow recovery. RESULTS: Repeated measures ANOVAs revealed significant main effects for all five composite scores (verbal memory, visual memory, reaction time, processing speed and total symptoms). In group analyses, performance decrements and symptoms relating to concussion appeared to largely resolve by 5 days post-injury and fully resolve by 10 days. Athletes' scores were examined individually using the reliable change methodology. At 1 day post-injury, 90% had two or more reliable declines in performance or increases in symptom reporting. At 10 days, 37% were still showing two or more reliable changes from pre-season levels. CONCLUSIONS: This study illustrates the importance of analysing individual athletes' test data because group analyses can obscure slow recovery in a substantial minority of athletes.

Adolescent↗

PubMed2006

Suppressed working memory on the WMS-III as a marker for poor effort.

The purpose of this study was to examine the clinical utility of memory minus Working Memory Index (memory-WMI) discrepancy scores on the WMS-III for detecting poor effort in 145 personal injury litigants (19 poor effort, 126 adequate effort). On average, participants in the poor effort group performed significantly lower on all WMS-III memory indexes and demonstrated larger memory-WMI discrepancy scores compared to participants in the adequate effort group. Discriminant function analyses using memory-WMI discrepancy scores as independent variables revealed poor overall classification rates (60.0% to 63.4%). Based on the prevalence of unusually suppressed attention-concentration ability relative to memory functioning using unidirectional memory-WMI discrepancy scores, high specificity and negative predictive power values were found. However, there was unacceptably low sensitivity and positive predictive power. These results suggest that memory-WMI discrepancy scores on the WMS-III do not provide clinically useful information regarding response set and should be used cautiously as an indicator of poor effort.

Adult↗

PubMed2006

Sensitivity of computerized neuropsychological screening in depressed university students.

This study examined the sensitivity of a computerized neuropsychological screening (ImPACT) to the cognitive effects of depression in a sample of 20 students with suspected depression and 20 healthy university students matched for gender, age, and education. Students with depression had slower reaction times (p < .02; d = .82, large effect) and processing speeds (p < .03; d = .77, large effect). The brevity and sensitivity of ImPACT to the cognitive effects of depression warrants further research with psychiatric populations.

Adolescent↗

PubMed2006

Clinical validation of the General Ability Index--Estimate (GAI-E): estimating premorbid GAI.

The clinical utility of the General Ability Index--Estimate (GAI-E; Lange, Schoenberg, Chelune, Scott, & Adams, 2005) for estimating premorbid GAI scores was investigated using the WAIS-III standardization clinical trials sample (The Psychological Corporation, 1997). The GAI-E algorithms combine Vocabulary, Information, Matrix Reasoning, and Picture Completion subtest raw scores with demographic variables to predict GAI. Ten GAI-E algorithms were developed combining demographic variables with single subtest scaled scores and with two subtests. Estimated GAI are presented for participants diagnosed with dementia (n = 50), traumatic brain injury (n = 20), Huntington's disease (n = 15), Korsakoff's disease (n = 12), chronic alcohol abuse (n = 32), temporal lobectomy (n = 17), and schizophrenia (n = 44). In addition, a small sample of participants without dementia and diagnosed with depression (n = 32) was used as a clinical comparison group. The GAI-E algorithms provided estimates of GAI that closely approximated scores expected for a healthy adult population. The greatest differences between estimated GAI and obtained GAI were observed for the single subtest GAI-E algorithms using the Vocabulary, Information, and Matrix Reasoning subtests. Based on these data, recommendations for the use of the GAI-E algorithms are presented.

Algorithms↗

PubMed2006

Ethical issues associated with the assessment of exaggeration, poor effort, and malingering.

The use of effort tests is standard practice in forensic neuropsychology. There is a tremendous amount of good information available in test manuals and the research literature regarding the proper and responsible use of these tests. However, it is clear that there are numerous ethical issues and considerations associated with the assessment of exaggeration, poor effort, and malingering. Many of these issues are discussed, and recommendations are provided.

Forensic Psychiatry↗

PubMed2006

Examining concussion rates and return to play in high school football players wearing newer helmet technology: a three-year prospective cohort study.

OBJECTIVE: The purpose of this study was to compare concussion rates and recovery times for athletes wearing newer helmet technology compared to traditional helmet design. METHODS: This was a three-year, prospective, naturalistic, cohort study. Participants were 2,141 high school athletes from Western Pennsylvania. Approximately half of the sample wore the Revolution helmet manufactured by Riddell, Inc. (n = 1,173) and the remainder of the sample used standard helmets (n = 968). Athletes underwent computerized neurocognitive testing through the use of ImPACT at the beginning of the study. Following a concussion, players were reevaluated at various time intervals until recovery was complete. RESULTS: In the total sample, the concussion rate in athletes wearing the Revolution was 5.3% and in athletes wearing standard helmets was 7.6% [chi (1, 2, 141) = 4.96, P < 0.027]. The relative risk estimate was 0.69 (95% confidence interval = 0.499- 0.958). Wearing the Revolution helmet was associated with approximately a 31% decreased relative risk and 2.3% decreased absolute risk for sustaining a concussion in this cohort study. The athletes wearing the Revolution did not differ from athletes wearing standard helmets on the mechanism of injury (e.g., head-to-head strike), on-field concussion markers (e.g., amnesia or loss of consciousness), or on-field presentation of symptoms (e.g., headaches, dizziness, or balance problems). CONCLUSION: Recent sophisticated laboratory research has better elucidated injury biomechanics associated with concussion in professional football players. This data has led to changes in helmet design and new helmet technology, which appears to have beneficial effects in reducing the incidence of cerebral concussion in high school football players.

Adolescent↗

PubMed2005

A new potential marker for abnormal cardiac physiology in depression.

The purpose of the study was to determine if a nonlinear estimate of dimensional complexity, Pointwise correlation dimension (Pd2), could be used to identify abnormal cardiac physiology associated with depression in primary care outpatients. The subjects were 22 medical controls and 30 general medical outpatients with depression who wore a cardiac monitor for 24 h. There was a significant difference between depressed and control subjects for Pd2 based on the entire cardiac time-series, with depressed subjects exhibiting higher Pd2 values. A cutoff score reflecting high dimensional complexity was selected, and an odds ratio was calculated demonstrating that patients with Pd2 values above the cut-off were 8.8 times more likely to fall in the depressed group than the control group. Additional research is needed to determine if Pd2 is useful for identifying physiological markers of depression.

Adult↗

PubMed2005

WAIS-III General Ability Index in neuropsychiatry and forensic psychiatry inpatient samples.

The purpose of this study is to examine the WAIS-III General Ability Index (GAI) in a sample of 33 neuropsychiatry inpatients and 47 forensic psychiatry inpatients. The GAI is comprised of the six subtests that form the Verbal Comprehension and the Perceptual Organization Indexes. The GAI, although highly correlated with the FSIQ, was on average 5.3 points higher in the neuropsychiatry sample and 4.2 points higher in the forensic psychiatry sample. The GAI was significantly higher than the Working Memory and the Processing Speed Indexes in both groups. The GAI, a composite measure of verbal and nonverbal intellect, appears to be an appropriate measure for use in day-to-day clinical practice in neuropsychology. To facilitate clinical use, statistically reliable difference scores between the GAI and the WMI and PSI, for the 95% confidence interval, are presented.

Adolescent↗

PubMed2005

Effects of mild traumatic brain injury cannot be differentiated from substance abuse.

PRIMARY OBJECTIVE: Patients involved in litigation relating to mild traumatic brain injury (MTBI) typically undergo a forensic neuropsychological evaluation. However, if cognitive problems are identified, it is difficult to know whether these are related to the MTBI or other factors such as pre- and/or post-injury substance abuse. The purpose of this study was to compare the neuropsychological test performances of 73 patients with acute, uncomplicated MTBIs to a sample of 73 patients from an inpatient substance abuse programme. METHODS AND PROCEDURES: Patients were perfectly matched on age, education and gender. Ten cognitive measures were used that included the Trail Making Test (TMT) and selected sub-tests from the Wechsler Memory Scale-Revised. MAIN OUTCOMES AND RESULTS: Patients with MTBI demonstrated poorer performances on Digits Backwards (p < 0.028) and TMTA (p < 0.032). There were no significant differences between the two groups on the remaining cognitive measures. The clinical usefulness of these measures to differentiate between the groups, using discriminant function analysis, was very poor. CONCLUSIONS: Patients with uncomplicated MTBIs could not be reliably differentiated from patients with substance abuse problems on these measures of concentration, memory and processing speed.

Adolescent↗

PubMed2005

Interpreting the trail making test following traumatic brain injury: comparison of traditional time scores and derived indices.

The purpose of this study was to examine the clinical application of traditional time scores and various derived indices from the Trail Making Test (TMT) in a sample of 571 patients with acute traumatic brain injury (TBI). Participants were classified into four injury severity groups. A clear linear relation between injury severity and TMT performance was demonstrated, with the more severely brain injured patients performing more poorly on most measures. Hierarchical logistic regression analysis of TMT time scores across binary extreme groups based on injury severity resulted in high classification rates for patients with very mild TBI (93.0% correctly classified) and low classification rates for patients with moderate to severe TBI (50.0% correctly classified). However, TMT derived indices did not provide a unique contribution to test interpretation beyond what is already available from Part A and B separately.

Adult↗

PubMed2005

Validity of ImPACT for measuring processing speed following sports-related concussion.

The purpose of this study was to examine the validity of ImPACT (Immediate Post-Concussion Assessment and Cognitive Testing), a computerized neuropsychological test battery, for measuring attention and processing speed in athletes with concussions. This was accomplished by comparing the computerized testing to a traditional neuropsychological measure, the Symbol Digit Modalities Test (SDMT). Participants were 72 amateur athletes who were seen within 21 days of sustaining a sports-related concussion (Mean = 9.4, SD = 5.4 days). As predicted, the SDMT correlated more highly with the Processing Speed and Reaction Time composites than the Verbal Memory and Visual Memory Composites from ImPACT. The composite scores from ImPACT and the SDMT were subjected to exploratory factor analysis, revealing a two-factor solution interpreted as Speed/Reaction Time and Memory. It appears as if the Processing Speed Composite, Reaction Time Composite, and SDMT are measuring a similar underlying construct in this sample of concussed amateur athletes.

Adolescent↗

PubMed2005

Outcome from mild traumatic brain injury.

PURPOSE OF REVIEW: The focus of this review is outcome from mild traumatic brain injury. Recent literature relating to pathophysiology, neuropsychological outcome, and the persistent postconcussion syndrome will be integrated into the existing literature. RECENT FINDINGS: The MTBI literature is enormous, complex, methodologically flawed, and controversial. There have been dozens of studies relating to pathophysiology, neuropsychological outcome, and the postconcussion syndrome during the past year. Two major reviews have been published. Some of the most interesting prospective research has been done with athletes. SUMMARY: The cognitive and neurobehavioral sequelae are self-limiting and reasonably predictable. Mild traumatic brain injuries are characterized by immediate physiological changes conceptualized as a multilayered neurometabolic cascade in which affected cells typically recover, although under certain circumstances a small number might degenerate and die. The primary pathophysiologies include ionic shifts, abnormal energy metabolism, diminished cerebral blood flow, and impaired neurotransmission. During the first week after injury the brain undergoes a dynamic restorative process. Athletes typically return to pre-injury functioning (assessed using symptom ratings or brief neuropsychological measures) within 2-14 days. Trauma patients usually take longer to return to their pre-injury functioning. In these patients recovery can be incomplete and can be complicated by preexisting psychiatric or substance abuse problems, poor general health, concurrent orthopedic injuries, or comorbid problems (e.g. chronic pain, depression, substance abuse, life stress, unemployment, and protracted litigation).

Journal Article↗

PubMed2005

Women with low activity are at increased risk for depression.

This study assessed if there are sex differences in the relationship between amount of physical activity and depression in primary care outpatients. Participants (N= 111), referred by their family physicians, wore a heart-rate monitor for 24 hr. The two-lead monitor collected the number of beats per minute and minute-averaged horizontal movement data, e.g., from walking or moving about. All participants underwent structured clinical interviewing using the Structured Clinical Interview for DSM-IV and completed the Beck Depression Inventory-II and the Symptom Checklist-90-Revised. For the total sample, patients with low activity were more likely to be depressed (p<.006). Adults under the age of 45 (n=85) with low activity were 7.4 times more likely to be depressed than young adults who showed normal activity. However, in adults 45 or older, there was no relationship between activity and depression. In a subsample of women under the age of 55 (n=70), 91% of the low activity group and 39% of the normal activity group were diagnosed with depression (p<.003). Women in the low activity group were 15.7 times more likely to be depressed than women in the normal activity group. In contrast, there was no relationship between activity and depression in men. Additional research is needed to assess whether low activity is a potent predictor of depression in women.

Depression↗

PubMed2004

Relation between subjective fogginess and neuropsychological testing following concussion.

The purpose of this study was to examine the relation between the subjective report of feeling foggy at one-week post concussion and acute neuropsychological outcome. The outcome variables were derived from a computerized neuropsychological screening battery, Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT). Participants were 110 high school students who sustained a sports-related concussion and were evaluated 5-10 days post injury (M = 6.8 days). Athletes were divided into two groups on the basis of self-reported fogginess. The first group reported no fogginess (n = 91), whereas the second group reported experiencing some degree of fogginess (n = 19) on a 6-point scale. The athletes with persistent fogginess experienced a large number of other post-concussion symptoms, compared to the athletes with no reported fogginess. In addition, the athletes with persistent fogginess had significantly slower reaction times, reduced memory performance, and slower processing speed. Thus, athletes with any degree of self-reported fogginess at one-week post injury are likely to have adverse effects from their concussions in multiple domains.

Adolescent↗

PubMed2004

Objective assessment of psychomotor retardation in primary care patients with depression.

The relationship between activity level and depression in primary care outpatients was examined. Forty-eight patients with depression and 25 general medical controls wore a heart and activity level monitor for 24 h. Minute-averaged horizontal movement was collected. Patients with depression were sorted into two equal groups based on a median split of their Beck Depression Inventory-II scores. ANOVAs revealed significant main effects for average movement over the 24-h interval, average movement between 12 and 6 P.M., and a measure of "high activity" level. Patients with more severe depression had lower activity levels than the other two patient groups. The nondepressed and less severely depressed groups were combined and compared to the more severely depressed group using a standard discriminant function analysis. The overall correct classification rate was 74.0%, with 86% of the combined group and 50% of the more severely depressed group correctly classified. Patients with low activity levels were 6.0 times more likely to fall in the severely depressed group than patients with more normal activity levels.

Depressive Disorder↗

PubMed2004

Cumulative effects of concussion in amateur athletes.

PRIMARY OBJECTIVE: To examine the possibility that athletes with multiple concussions show cumulative effects of injury. METHODS AND PROCEDURES: Amateur athletes with a history of three or more concussions were carefully matched (gender, age, education and sport) with athletes with no prior concussions. All completed a computerized neuropsychological test battery at preseason (ImPACT) and then within 5 days of sustaining a concussion (mean = 1.7 days). MAIN OUTCOMES AND RESULTS: There were differences between groups in symptom reporting and memory performance. At baseline (i.e. preseason), athletes with multiple concussions reported more symptoms than athletes with no history of concussion. At approximately 2 days post-injury, athletes with multiple concussions scored significantly lower on memory testing than athletes with a single concussion. Athletes with multiple concussions were 7.7 times more likely to demonstrate a major drop in memory perfomance than athletes with no previous concussions. CONCLUSIONS: This study provides preliminary evidence to suggest that athletes with multiple concussions might have cumulative effects.

Adolescent↗

PubMed2004

Self-organizing neural network analyses of cardiac data in depression.

OBJECTIVE: To determine if an unsupervised self-organizing neural network could create a clinically meaningful distinction of 'depression' versus 'no depression' based on cardiac time-series data. DESIGN: A self-organizing map (SOM) was used to separate the time-series of 84 subjects into groups based on characteristics of the data alone. MATERIALS AND METHODS: Analyses included natural log transformations and two types of filtering to enhance characteristics of the data as well as classifications of unprocessed data. A Pearson chi(2) analysis was performed to determine if the SOM groups bore any relation to the binary clinical groups. RESULTS: Overall correct SOM classifications ranged from 54 to 70.2% with two classifications being clinically meaningful. CONCLUSIONS: SOM classifications of cardiac time-series data with enhanced ultradian variations and cardiac data recorded around the interval when a person was in bed were useful in differentiating clinically meaningful subgroups with and without depression.

Adult↗