Reaction time (RT) is often used in the assessment of patients with traumatic brain injury (TBI), presumably because it reflects either information processing speed or attentional capacity. To clarify this distinction, we examined behavioral RT and the within-subject variability of RT as they relate to electrophysiological measures of attention and information processing. These include the P300 latency, which reflects stimulus evaluation time, P300 amplitude, which reflects attentional allocation, and the preresponse component of the contingent negative variation (CNV), which reflects sustained attention. We found that the latency and variability in behavioral RT were not correlated with the latency or variability of the P300, suggesting that stimulus evaluation time is not a major contributor to RT and its variability in this paradigm. However, among normal controls, RT was related to P300 amplitude, and therefore to attentional allocation. For the TBI subjects, it was the variability, not the speed, of RT that was related to P300 amplitude and to the preresponse component of the CNV. These data suggest that, while in normal controls RT reflects attentional allocation, among TBI subjects it is the variability in RT that is sensitive to the ability to allocate and sustain attention. (JINS, 1997, 3, 95–107.)

Clinically, tests of executive functions tend to be chosen on face validity. If such tests are to be used to evaluate a clinical population, their ability to measure executive functions should be reliably demonstrated in a normal population. In order to investigate the reliability of such tests, a sample of 130 normal adults (74 women, 56 men) ages 17 to 55 years were administered 4 tests purporting to measure planning/problem-solving: the Tower of London Test, the Six Element Test, the Twenty Questions Test, and the Rey Complex Figure Test. A structural equation modeling approach provided by the LISREL 8 program was used to evaluate three models hypothesized to explain the relationship among the test variables and the latent construct of planning/problem-solving. An adequate model was unable to be estimated, thus raising questions about the meaning of the latent construct planning/problem-solving and the psychometric structure of the Tower of London Test. (JINS, 1997, 3, 108–119.)

In this study we applied clustering procedures to a subgroup of 341 participants from the WAIS–R standardization sample. These individuals were selected by virtue of their having full-scale profiles characterized by scatter of greater than 8 scaled scores. Using a hierarchical clustering algorithm, a multistage procedure was used to establish and evaluate a cluster solution. The subject selection and clustering methods were successful in revealing a set of 9 profile types characterized by unique profile shapes. All profiles were associated with FSIQs that were at least in the average range. Seven of the profiles were characterized by specific subtest strengths, only 1 with subtest weaknesses. Examination of the external correlates of profile membership revealed differences among profile groups for age, marital status, education, and occupation. Our findings suggest that variability in and across the 9 profile types in this sample reflects increased contributions of unique abilities in comparison to the influence of the underlying primary and secondary WAIS–R dimensions of cognitive ability. (JINS, 1997, 3, 120–127.)

Whether multiple conscious efforts at word search bring a subject closer to an elusive word and to eventual successful retrieval remains a subject of debate. Previous work with normal participants has shown that multiple attempts eventuating in correct retrieval are not usually associated with a systematic progression toward target word phonology in the intervening attempts. In this study we analyzed the naming errors produced by 30 aphasic patients who had received the Boston Naming Test. The analyses were designed to elucidate the characteristics of responses that led to eventual success. Our data showed that among aphasics, as with normal subjects, the presence of target-initial phonology in the subject's first response was the most important predictor of correct retrieval. Moreover, progression towards target phonology in the course of multiple attempts was unrelated to eventual correct retrieval. (JINS, 1997, 3, 128–138.)

This longitudinal study examines the sensitivity of 2 computerized neuropsychological tests, delayed matching to sample and paired associate learning, to early dementia of the Alzheimer type (DAT). Normal controls, patients in the early stages of DAT, and individuals with questionable dementia (QD) were studied. At 6 and 12 months after initial presentation, almost half of the QD group exhibited lower scores on the computerized subtests, maintaining their scores on standard testing. Over the same period NC subjects maintained their performance levels, while DAT patients continued to deteriorate. Linear discriminant function analyses of the computerized subtests at 6 and 12 months correctly classified 100% of the early DAT patients. Eighty-four and 79 percent of normal controls were correctly classified at 6 and 12 months respectively. Further development of these subtests for the detection of early dementia and the documentation of ongoing change in DAT is warranted. The findings are discussed in terms of the special sensitivity of these tests to the neuropathology of Alzheimer's Disease. (JINS, 1997, 3, 139–146.)

This study compared postmeningitic children (N = 130) with grade and sex matched controls (N = 130) selected from target children's schools on measures of intellectual, linguistic, learning, and reading skills. Results showed that children with a history of meningitis are at greater risk for impairment in these areas, with experience of the disease prior to 12 months of age being an important risk factor. Within the postmeningitic sample presence of medical complications was associated with poorer verbal abilities. Finally, a significant relationship was identified between depressed language skills and later educational difficulty, with these findings interpreted with respect to both developmental and neuropsychological principles. (JINS, 1997, 3, 147–158.)

Neuropsychological assessment has been extensively used in the presurgical evaluation of temporal lobe epilepsy (TLE) patients to assist in determining lateralization of seizure onset. Very few studies have examined the accuracy with which commonly used neuropsychological instruments provide this information in the individual patient. In 81 patients (49 right-, 32 left-TLE) without space-occupying lesions in whom correct seizure lateralization was inferred on the basis of postsurgical seizure-free status, we compared the frequency with which discrepancies between the Wechsler Memory Scale–Revised (WMS–R; Wechsler, 1987) Verbal and Visual Memory Indices, Warrington Recognition Memory Test (WRMT; Warrington, 1984) Words and Faces scaled scores, and Intracarotid Amobarbital Procedure (IAP) hemispheric memory scores correctly predicted seizure lateralization in the individual patient. Using both clinical analysis and discriminant function analyses (DFA), the IAP was found to be a clearly superior predictor of seizure laterality to the neuropsychological measures, whether used individually or in combination with one another. Using clinical analysis the WRMT was found to be a superior predictor to the WMS–R, which frequently gave false lateralizing information. Using all 3 measures in combination with one another, 87.1% of patients were correctly lateralized using DFA. Correctly lateralized patients were older and had longer durations of seizure disorder. (JINS, 1997, 3, 159–168.)

Three patients with Gerstmann-Sträussler-Scheinker disease (GSS) caused by a serine-for-phenylalanine substitution at codon 198 of the prion protein gene (PRNP) were compared to 9 age- and education-matched non-mutation-carriers from the same large Indiana kindred (GSS–IK) on a comprehensive neuropsychological test battery. Clinically significant impairments in intelligence, secondary memory, attention and cognitive processing speed, executive ability, and manual motor skills were noted in 2 patients. The wide range and the severity of the cognitive deficits indicated generalized cerebral dysfunction consistent with global dementia. One patient, symptomatic for less than 1 year, had more selective deficits involving memory, motor skills, and verbal fluency, suggesting early subcortical involvement. (JINS, 1997, 3, 169–178.)

Researchers disagree as to whether Lewy body disease (LBD) constitutes a variant of Alzheimer's (AD) or Parkinson's disease (PD), or alternatively, whether it is an independent disease process. The neuropathological, genetic, and clinical characteristics of LBD are reviewed and compared to those of AD and PD. Data for 150 cases of LBD reported in the literature were compiled and grouped according to neuropathological status. Patients with pure LBD (with limited or no concurrent AD pathology) tend to present at a younger age with extrapyramidal signs followed by dementia, whereas patients with mixed LBD–AD (concurrent LB and AD pathology) are somewhat older and tend to present with dementia. The cognitive profile of LBD patients, and the relationships among LBD, AD, and PD remain unclear due to methodological limitations and the paucity of studies comparing the groups directly. (JINS, 1997, 3, 179–194.)

Some persons with Alzheimer's disease (AD) lose the ability to recognize themselves, as when they cannot overtly recognize their reflection in a mirror. There is evidence, however, that covert or unconscious self-recognition might be displayed in such individuals. In this study, 3 persons with AD lacking the ability to overtly self-recognize demonstrated multiple instances of unconscious or covert self-recognition. A variety of interventions, inspired by research with prosopagnosics, was implemented to remediate this loss. Interventions enabled all participants to exhibit overt self-recognition, though each did so with the aid of a different intervention. In addition, successful overt self-recognition required a verbal probe and was entirely intervention-dependent: When the intervention was removed, overt self-recognition was lost. Results support a dissociation between explicit–declarative versus implicit–nondeclarative memory systems, and extends this dissociation into the realm of self-recognition in AD. (JINS, 1997, 3, 195–198.)

In recent years, efforts have been made to computerize standard neuropsychological (NP) tests (Kane & Kay, 1992). This effort is in the service of increased productivity, lower costs, and an increase in the consistency of test administration. However, care must be taken to make sure the limitations of the computer interface do not compromise test validity.