Joseph Barrash

The neuroanatomical correlates of route learning impairment

Recent functional imaging studies of topographical learning point to the participation of a large network of cortical and subcortical regions. Nevertheless, areas which are crucial remain poorly specified due to the absence of group studies of subjects with focal lesions distributed throughout the brain. We assessed the ability of 127 subjects with stable, focal lesions to learn a complex real-life route, a critical aspect of topographical functioning. Results indicated that impairment in route learning was highly associated with damage to medial occipital and posterior parahippocampal cortices in either hemisphere, the right hippocampus, and the right inferotemporal region. Impairment was seen among 86% of the subjects with damage to any these regions, in contrast to impairment among 31% of subjects with lesions in other regions. The importance of medial occipitotemporal cortices bilaterally and right inferotemporal cortex likely reflects the critical role of the ability to quickly and accurately perceive and learn multiple topographical scenes. The importance of the right (and probably left) posterior parahippocampal gyrus and of the right hippocampus likely reflects their critical, distinctive roles forming an integrated representation of the extended topographical environment (i.e., the appearance of places and spatial relationships between specific places), and consolidating that representation into multifaceted contextual knowledge of the environment.

Memory performance after head injury: contributions of malingering, litigation status, psychological factors, and medication use

Impaired memory test performance can reflect a host of factors, such as head injury/postconcussive syndrome, involvement in litigation, malingering behavior, psychological distress, and medication use. Such factors are important in interpreting memory test performances in patients referred in the context of litigation. We examined memory test performance in mild head-injured patients in litigation, mild to moderate head-injured patients not in litigation, severely head-injured patients not in litigation, depressed patients, and patients with somatization disorders. Findings showed that several memory tests were useful in distinguishing probable malingerers from the other groups. There was a complex interaction among malingering status, psychological status, and medication use in the prediction of memory test results. Although nonneurological factors were related to memory impairment, litigation status alone was not predictive of memory performance. The results emphasize the need to consider nonneurological factors in the interpretation of poor memory performance in patients seen for forensic evaluation.

Detecting poor effort and malingering with an expanded version of the Auditory Verbal Learning Test (AVLTX): Validation with clinical samples

Three studies describe the development and validation of a new procedure (AVLTX) to detect inadequate effort or malingering by adding 60-min delayed recall/recognition trials and identifying “impaired” memory performances that are highly inconsistent with performances of brain-damaged (BD) individuals. In Study I, AVLTX performances of 25 probable malingerers (PMs) were compared with those of 43BD and 40 psychiatric patients (PSYs). Seven inconsistencies were identified and converted to scaled inconsistency scores, yielding the exaggeration index (EI). Study II reported cross-validation in an independent sample of 34 PM, 70BD and 89 PSY, showing sensitivity of 0.59 and specificities of 0.97 (BD) and 0.92 (PSY). Study III compared the diagnostic accuracy of the EI with two well-established effort assessment paradigms, exemplified by the RMTand DRT (a symptom validity test). The RMT showed excellent sensitivity and poor specificity; the DRT showed poor sensitivity and excellent specificity; the EI showed good sensitivity and excellent specificity. Adding a second delayed trial to list-learning tests can be a time-efficient procedure to detect inadequate effort.

Neurologic and neurobehavioral effects of electric and lightning injuries

There are few studies of the effects of electric and lightning injuries (ELI) on the neurologic and neuropsychological status of injured patients. We reviewed records of fourteen patients with ELI injuries seen at our hospital (12 with high-voltage electric and two with lightning injury). Eight had cardiac arrest after injury, and 10 had neurologic complaints when first evaluated. Eight had normal neuroimaging results. Six had electroencephalograms; four showed abnormal results. Thirteen underwent neuropsychological testing. Twelve (92%) showed cognitive dysfunction including impairments in memory, attention, and affective disturbances (anxiety, depression, irritability, and poor frustration tolerance). Five of 12 (62%) had multiple physically aggressive outbursts, not present before the injury. Patients with cardiac arrest did not differ in neurologic psychologic testing from patients not sustaining cardiac arrest. Patients with ELI who had neurobehavioral symptoms had a coherent syndrome characterized by disturbances in cognition (attention and memory), mood (distress with prominent irritability), and behavior (aggressive outbursts). Serial neurologic and neuropsychological evaluations will aid in better defining the sequelae of ELI.

Age‐related decline in route learning ability

The effect of normal aging on route learning ability was investigated, employing a complex, real‐life route. Performance was not related to gender or education but was strongly related to age. Difficulty learning the route (i.e., total errors across three repeated trials) increased monotonically in successive age groups. Decline became particularly apparent in the 60‐ to 69‐year‐old group and was even more pronounced in the 70+ group, which averaged more than four times as many errors as the youngest group (18 to 39 years) on each of the three trials. In addition to normal age‐related decline, defective route learning was seen in subjects in the oldest groups. The findings indicate that an ecologically valid test may be especially sensitive to age‐related decline in route learning ability.

Prediction of Driving Ability With Neuropsychological Tests: Demographic Adjustments Diminish Accuracy

Demographically adjusted norms generally enhance accuracy of inferences based on neuropsychological assessment. However, we hypothesized that demographic corrections diminish predictive accuracy for real-world activities with absolute cognitive demands. Driving ability was assessed with a 45-minute drive along a standardized on-road route in participants aged 65+ (24 healthy elderly, 26 probable Alzheimers disease, 33 Parkinsons disease). Neuropsychological measures included: Trail-Making A and B, Complex Figure, Benton Visual Retention, and Block Design tests. A multiple regression model with raw neuropsychological scores was significantly predictive of driving errors (R2 = .199, p = .005); a model with demographically adjusted scores was not (R2 = .113, p = .107). Raw scores were more highly correlated with driving errors than were adjusted scores for each neuropsychological measure, and among healthy elderly and Parkinsons patients. When predicting real-world activities that depend on absolute levels of cognitive abilities regardless of demographic considerations, predictive accuracy is diminished by demographic corrections.

Dimensions of personality disturbance after focal brain damage: investigation with the Iowa Scales of Personality Change.

This study employed a multistep, rational–empirical approach to identify dimensions of personality disturbance in brain-damaged individuals: (a) Five dimensions were hypothesized based on empirical literature and conceptual grounds; (b) principal components analysis was performed on the Iowa Scales of Personality Change (ISPC) to determine the pattern of covariance among 30 personality characteristics; (c) when discrepancies existed between principal components analysis results and conceptually based dimensions, empirical findings and clinical considerations were weighed to determine assignment of ISPC scales to dimensions; (d) the fit of data to the refined dimensions was assessed by examination of intercorrelations; (e) differential predictions concerning the relationship of dimensions to ventromedial prefrontal cortex (vmPFC) damage were tested. This process resulted in the specification of five dimensions: Disturbed Social Behavior, Executive/Decision-Making Deficits, Diminished Motivation/Hypo-Emotionality, Irascibility, and Distress. In accord with predictions, the 28 participants with vmPFC lesions, compared to 96 participants with focal lesions elsewhere in the brain, had significantly more Disturbed Social Behavior and Executive/Decision-Making Deficits and tended to have more Diminished Motivation/Hypo-Emotionality. Irascibility was not significantly higher among the vmPFC group, and the groups had very similar levels of Distress. The findings indicate that conceptually distinctive dimensions with differential relationships to vmPFC can be derived from the Iowa Scales of Personality Change.

Consistency of neuropsychological outcome following damage to prefrontal cortex in the first years of life

The consistency of neuropsychological outcome following circumscribed damage to the prefrontal cortex (PFC) in the first years of life has not been systematically investigated. On the basis of a single well-studied case, Ackerly and Benton (1948) postulated that the core profile involves development of a primary social defect in the context of generally normal intellectual abilities. We evaluated the consistency of this profile across all patients in our registry who had focal PFC damage acquired between the prenatal period and 62 months of age (N = 7). Clinical ratings based on detailed evaluations, parental ratings, and neuropsychological testing confirmed this general profile in 5 of the 7 patients. The impairments of social function were evident in early childhood and persisted into adult life. Of the 2 patients who did not fit this profile, 1 had significant social impairment in the context of broader cognitive deficits, and 1 had no significant impairment of social or intellectual function. The profile was not observed in a comparison group with childhood-onset nonfrontal lesions. These findings support the notion that focal damage to PFC in the first years of life leads to the development of substantial impairment of social competencies, albeit with some variability in outcome. Further, the findings highlight the importance of emotional dysfunction and poor behavior regulation in the development of these impairments. Our studies recapitulate and confirm the core messages set forth by Ackerly and Benton more than a half-century ago.

A longitudinal study of transient epileptic amnesia.

ObjectiveTo study the underlying pathophysiology and the long-term prognosis of the syndrome of transient epileptic amnesia (STEA). BackgroundSTEA has been recently described as a distinct nosologic entity, in which memory impairment is the sole clinical manifestation of temporal lobe epilepsy. MethodsSerial neuropsychologic examinations and electroencephalography (EEG) were performed on a patient with STEA, before and after treatment with antiepileptic drug for a 2-year study period. ResultsInitial neuropsychologic assessment revealed isolated mild-to-moderate impairment in anterograde verbal and visual memory. EEG showed intermittent sharp and spike discharges from both temporal regions, independently, consistent with an underlying seizure tendency. Treatment with extended-release carbamazepine 200 mg twice daily led to complete resolution of the memory difficulty, and the repeat neuropsychologic assessment and EEG were within normal limits. Two years after the treatment was initiated, the patient remained asymptomatic and a third neuropsychologic assessment was completely normal. ConclusionsThe memory impairment in STEA does not originate from a progressive neurodegenerative mechanism, but rather from an underlying epileptic and therefore reversible etiology. When identified and treated, STEA carries no memory impairment at 2 years after diagnosis.

Exaggeration index for an expanded version of the auditory verbal learning test: robustness to coaching.

Recent research suggests that effort detection measures based on patterns of neuropsychological performance may be more robust to coaching than traditional effort detection measures. In the present study, we evaluated the Exaggeration Index for an extended version of the Auditory Verbal Learning Test (EI-AVLTX), a recently developed effort detection instrument based on patterns of performance on the AVLT using a simulated malingering paradigm. In two independent samples, the EI-AVLTX was1 found to be relatively sensitive and specific to malingering, and robust to the effects of a warning about malingering detection.