Complex real-world functioning and neuropsychological test performance in older adults.

In stepwise regression analyses with Independent Living Scales (ILS) summary and subscale scores as the dependent variables, 8 of 10 psychometric measures from our battery for older adults emerged as important predictors for 69 patients referred for clinical assessment. The Dementia Rating Scale (DRS) score entered first for 6/8 analyses. However, measures of confrontation naming, oral reading, verbal fluency, paragraph recall, visual perception, complex attention, and depression also added explanatory power. Multiple Rs ranged from .66 to .88 except for the Social Adjustment subscale, which correlated only with the depression scale.

Cerebral concussion in athletes: evaluation and neuropsychological testing.

OBJECTIVE: To conduct a topic review of studies related to cerebral concussion in athletes, as an aid to improving decision-making and outcomes. METHODS: We review the literature to provide an historical perspective on the incidence and definition of and the management guidelines for mild traumatic brain injury in sports. In addition, metabolic changes resulting from cerebral concussion and the second-impact syndrome are reviewed, to provide additional principles for decision-making. Neuropsychological testing, as it applies to athletes, is discussed in detail, to delineate baseline assessments, the characteristics of the neuropsychological evaluation, the neuropsychological tests used, and the methods for in-season identification of cerebral concussion. Future directions in the management of concussions are presented. RESULTS: The incidence of cerebral concussions has been reduced from approximately 19 per 100 participants in football per season to approximately 4 per 100, i.e., 40,000 to 50,000 concussions per year in football alone. The most commonly used definitions of concussion are those proposed by Cantu and the American Academy of Neurology. Each has associated management guidelines. Concussion or loss of consciousness occurs when the extracellular potassium concentration increases beyond the upper normal limit of approximately 4 to 5 mmol/L, to levels of 20 to 50 mmol/L, inhibiting the action potential and leading to loss of consciousness. This phenomenon helps to explain the delayed effects of symptoms after trauma. CONCLUSION: Neuropsychological testing seems to be an effective way to obtain useful data on the short-term and long-term effects of mild traumatic brain injury. Moreover, knowledge of the various definitions and management strategies, as well as the utility of neuropsychological testing, is essential for those involved in decision-making with athletes with mild traumatic brain injuries.

Adaptive decision making, ecological validity, and the frontal lobes.

Existing neuropsychological procedures assess veridical, but not adaptive, decision making, which are based on different mechanisms. This severely curtails the tests' ecological validity, because most real-life decision making situations are adaptive, rather than veridical. Veridical decision making entails finding the correct response intrinsic to external situations and is actor-independent. Adaptive decision making is actor-centered and priority-based. Prefrontal cortex is critical for adaptive decision making. Innovative actor-centered decision-making tasks are required to better understand frontal lobe functions. We have designed a prototype for such procedures, the Cognitive Bias Task (CBT). CBT elicited strong gender and hemispheric differences in the effects of focal frontal lesions, which are more robust than those elicited with veridical tasks, such as the Wisconsin Card Sorting Test.

Adaptive versus veridical decision making and the frontal lobes.

Adaptive decision making and veridical decision making are based on different mechanisms. Veridical decision making is based on the identification of the correct response, which is intrinsic to the external situation and is actor-independent. Adaptive decision making is actor-centered and is guided by the actor's priorities. The prefrontal cortex is particularly critical for adaptive decision making and less so for veridical decision making. However, most experimental procedures used in cognitive psychology and neuropsychology focus on veridical decision making and ignore adaptive decision making. Innovative experimental procedures are required to characterize the contribution of the prefrontal cortex to adaptive decision making. We have designed a prototype for such procedures, the Cognitive Bias Task, and present the novel findings generated by this task.

Neurobehaviour rounds and interdisciplinary education in neurology and psychiatry (698).

Increasing emphasis on interdisciplinary medical treatment and education suggests that something valuable has arisen from medical specialization beyond the further development of specialty knowledge: an integration of specialty knowledge that compliments and extends the integrating aspects of the primary care approach to medicine. Several educational models have been described which serve this function. In this paper the authors describe interdisciplinary clinical teaching, and research team linking neurology, neuroradiology, psychiatry and neuropsychology. The team provides neurobehavioural evaluations and sponsors monthly Neurobehaviour Rounds, an interdisciplinary patient conference that is the main formal teaching vehicle for the programme. After the model had been in place for 1 year, eight of nine neurology residents had Residency In-Service Training Examination scores in behavioural neurology that exceeded their overall average scores. This suggests that encouraging neurology residents to see patients through the eyes of different specialists may have contributed to improvement in their performance on a test of interdisciplinary knowledge. A neurobehavioural programme anchored to a formal neurobehaviour conference may encourage interdisciplinary learning within the related disciplines of neurology, neuropsychology and psychiatry.

Wisconsin Card Sorting Test performance in above average and superior school children: relationship to intelligence and age.

This study explores the relationship of intelligence and age to scores on the Wisconsin Card Sorting Test, a measure of executive function. A sample of 26 normal children with Wechsler Intelligence Scale for Children-III (WISC-III) Full-Scale IQS above 130 and 24 normal children with WISC-III Full-Scale IQS between 110 and 129 were administered the test. A comparison to published norms revealed that above average children outperformed the average 9- to 14-year-old child on every measure at every age. Multiple regression analyses statistically related the Wisconsin Card Sorting Test, perseverative, nonperseverative, total errors, and trials to the first category of intelligence. Intelligence proved to be a significant qualifier of age trends. Gender relationships were nonsignificant in a preliminary analysis.

Perseverative behavior in Alzheimer's disease and subcortical ischemic vascular dementia.

Perseverative behavior has not been extensively studied in patients with dementia. In this study, perseverative behavior was elicited with the dementia version of the Graphical Sequence Test. A control group and participants with Alzheimer's disease (AD) and subcortical ischemic vascular dementia (IVD) were studied. A factor analysis revealed a 3-factor model consisting of perseverations related to semantic knowledge, motor functioning, and a third, intermediary factor. IVD participants made more total perseverations than did AD participants. Perseverations made by AD participants were correlated with deficits on tests of semantic knowledge, whereas the perseverations made by IVD participants were correlated with motor and frontal systems tests. Results are consistent with the view that perseverative behavior is hierarchically arranged in terms of specific levels of cognitive complexity and the overall pattern of cognitive deficits associated with each type of dementia.

Generalization effects of training on the Wisconsin Card Sorting Test for schizophrenia patients.

Several studies have demonstrated that schizophrenia patients can improve their performance on the Wisconsin Card Sorting Test if given appropriate training. However, it is not clear if they are learning a generalizable problem-solving strategy rather than a circumscribed rule. We examined this question by training patients on one of two related problem-solving tests and assessing transfer of training effects across the two instruments; a third group received practice on both tests, but no training. Subjects were 27 schizophrenia patients in the latter stages of an acute hospital admission. While subjects in both training conditions exhibited marked improvement on the trained test, the results failed to reveal any evidence of generalization. Subjects trained on one test performed no better on the other instrument than subjects who received practice only. These results suggest that gains in WCST performance reported in the literature after brief training or instructions may not reflect any meaningful changes in problem solving capacity or in any underlying neurological function. Implications of the findings for rehabilitation programs are discussed, along with limitations of the data and recommendations for future research.

The Cognitive Bias Task and lateralized frontal lobe functions in males.

The Cognitive Bias Task (CBT) is a multiple-choice response selection paradigm characterized by inherent ambiguity. All items offer a range from extremely context-dependent to extremely context-invariant responses. Lateralized prefrontal lesions produce extreme, and opposite, response biases on CBT in right-handed males. Healthy control subjects perform in the middle range. Findings suggest a dynamic balance between two synergistic decision-making systems in the frontal lobes: context-dependent in the left hemisphere and context-invariant in the right. The robust lateralized effects, which are dependent on task ambiguity, are sensitive and specific to frontal dysfunction. CBT is discussed in comparison with the Wisconsin Card Sorting Test as a potential cognitive activation task for functional neuroimaging of the frontal lobes.

Lateralization of frontal lobe functions and cognitive novelty.

The two hemispheres are functionally different in ways not adequately captured by the classic distinction between linguistic and nonlinguistic processes. The right hemisphere is critical for processing novel cognitive situations. The left hemisphere is key to the processes mediated by well-routinized representations and strategies. The left frontal systems appear to be critical for the cognitive selection driven by the content of working memory and for context-dependent behavior, the right frontal systems for cognitive selection driven by the external environment and for context-independent behavior. The crucial role of the right hemisphere in processing cognitively novel situations underscores the importance of the right frontal systems in task orientation and in the assembly of novel cognitive strategies.

Cognitive bias, functional cortical geometry, and the frontal lobes: laterality, sex, and handedness.

Abstract Performance of patients with quadrant lesions on the inherently ambiguous Cognitive Bias Task (CBT) suggests sexual dimorphism in the fundamental aspects of functional cortical geometry, by emphasizing different cerebral axes. In right-handed males, extreme context-dependent and context-independent response selection biases are reciprocally linked to left vs. right frontal systems. In right-handed females, these complementary biases appear to be reciprocally linked to posterior vs. frontal cortices. Frontal lobe functions are more lateralized in males than females due to sexual dimorphism of the left frontal systems. Both in males and females, patterns of CBT scores in non-right-handers with quadrant lesions are opposite to those found in right-handers. This suggests the existence of two functionally and neurally distinct cognitive selection mechanisms. Both mechanisms involve the frontal lobes, but their exact neuroanatomy depends on sex and handedness.

Remediation of cognitive deficits in schizophrenia.

Studies have suggested that schizophrenia is characterized by an impairment in the dorsolateral prefrontal cortex that prevents learning of some elementary information processing tasks. To test this hypothesis, the authors administered the Wisconsin Card Sorting Test to 16 schizophrenic inpatients with standard instructions and either contingent or noncontingent reinforcement. Performance was markedly impaired under each condition. A second cohort (N = 12) was tested after receiving instructions plus rehearsal and feedback. These subjects' performance was comparable to nonpatient norms and was maintained on a subsequent day. The results indicate that deficits in performance on the Wisconsin Card Sorting Test are remediable, whether or not they are due to neurological impairment.