The impact of psychological disturbances on immediate memory.

The current study tested the hypothesis that attention mediates the impact of psychological disturbances (i.e. depression, loss of self-control, and bizarre thinking) on immediate memory. A hypothesized model, in which psychological disturbances indirectly impacted immediate memory via attention, was tested using structural equations modeling (EQS). The participants included heterogeneous groups of brain-damaged and psychiatric subjects both with and without age-corrected observed variables. These groups did not vary with regard to the relationships within the model, and all models had good fit indices [comparative fit index (CFI)>0.98]. Competing models with paths directly from psychological disturbances to verbal, spatial, and general immediate memory were not significant, and these competing models did not result in a better fitting model. Therefore, the best fitting, most parsimonious model was the hypothesized one. These results corroborate the hypothesis of an indirect relationship between psychological disturbances and immediate memory via attention.

Development and initial validation of an Arabic version of the Expanded Trail Making Test: implications for cross-cultural assessment.

The performances of Sudanese subjects, both normal and brain damaged, on an Arabic version of the Expanded Trail Making Test were compared to those of normal and brain-damaged subjects from the United States, who completed the standard English version of this test. Preliminary psychometric properties of the Arabic version of the Expanded Trail Making Test were defined. Significant intergroup differences in performance were observed. Interestingly, the performances of Sudanese normals were found to be similar to those of U.S. brain-damaged subjects. The results are discussed in terms of reducing neuropsychological diagnostic errors attributable to ethnocultural factors.

Subject-selection procedures in neuropsychological research: a meta-analysis and prospective study.

The present study examined methods of control- and experimental-subject selection in neuropsychological research. Using both meta-analytic and prospective procedures, it was found that varied subject-selection procedures can potentially confound the results of neuropsychological studies and, by extension, can thwart the formulation of laws regarding neuropsychological function. In terms of selecting control subjects, the current findings suggest that individuals who self-report a negative history for neuropathology and psychopathology are adequate, perhaps even preferable, for inclusion. In terms of selecting experimental subjects, it appears preferable, if not essential, to obtain lesion confirmation through relevant neurodiagnostic tests. Based on these findings, it is recommended that subject selection be made on the basis of scientific merit rather than convenience or availability.

On the reliability, validity, and cognitive structure of the Thurstone Word Fluency Test.

The Thurstone Word Fluency Test (TWFT) is a widely used neuropsychological instrument. However, data regarding its psychometric properties are lacking. The results of the present study suggest that the TWFT possesses excellent test-retest and inter-rater reliability, in addition to good construct validity. However, its criterion validity is limited by its lack of specificity and sensitivity. The present study also suggests that the TWFT is a complex cognitive task, and that successful TWFT performance depends upon a constellation of cognitive abilities, including attention/concentration, psychomotor speed, and memory. Finally, the relationship between verbal IQ and TWFT letter association value was examined. While the TWFT appears to be useful in detecting the presence of cerebral dysfunction, it is of less value in localizing such dysfunction. It is argued that the TWFT should not be used as a neuropsychological screening instrument, but rather, is best used within the context of a thorough neuropsychological examination.

Neuropsychological performance of adults evidencing Attention-Deficit Hyperactivity Disorder.

Attention-Deficit Hyperactivity Disorder (ADHD) is no longer believed to be a time-limited syndrome manifested in and restricted to childhood and adolescence. Many of the characteristics associated with the disorder continue in variable form into adulthood. This investigation focused on two measures sensitive to attention, cognitive flexibility, and visual and auditory distraction, to determine if individuals diagnosed with ADHD would perform poorly in comparison with normal control subjects. Forty-two subjects, 27 ADHD adults and 15 control subjects, were administered the Goldman-Fristoe-Woodcock Test of Auditory Discrimination (TOAD), and the Stroop Color and Word Test. The findings indicated that the TOAD Noise subtest significantly discriminated the subjects, resulting in an overall correct classification rate of 80.95%.

Methodological considerations in the neuropsychological study of central nervous system underarousal with a specific emphasis on coma.

Several obstacles exist that impede the scientific study of pathological underarousal (stupor and coma). For instance, there is a lack of a clear, rational, standardized taxonomy with which to describe the phenomenon. Moreover, there is considerable confusion of the construct of arousal with other neurobehavioral constructs. The field also suffers from a general lack of acceptably reliable and valid instruments, especially measures of long-term outcome. Additionally, current treatments for chronic pathological underarousal are frequently presumptive and applied haphazardly, and thus do little to elucidate the process of recovery. It is suggested that biomedical and neuropsychological approaches to the study and treatment of pathological underarousal are complementary and that it is useful to view pathological underarousal as a behavioral, as well as a medical, phenomenon.

The expanded Trail Making Test: rationale, development, and psychometric properties.

Many procedures have been employed to determine the specific cognitive components necessary for successful Trail Making Test (TMT) performance. Yet, there is still considerable disagreement in the literature as to what these components might be. The present study explores an alternative methodology to address this problem. By systematically varying the stimuli within the TMT format, it may eventually be possible to isolate the cognitive demands of this test. As the first step toward this goal, two experimental forms of the TMT, forms X and Y, were developed and subjected to empirical validation. The results indicate that this Expanded Trail Making Test possesses adequate concurrent and criterion validity to support the proposed methodology. The results also suggest that the psychometric properties of the TMT format are robust to alterations in test stimuli. Secondary benefits of this methodology, in terms of explaining between-group variance and in terms of cross-cultural assessment, are discussed.

Assessment of level of consciousness following severe neurological insult. A comparison of the psychometric qualities of the Glasgow Coma Scale and the Comprehensive Level of Consciousness Scale.

An alternative method of coma assessment is presented and compared with the Glasgow Coma Scale. The merits of the Comprehensive Level of Consciousness Scale as a research tool are presented. An analysis of 101 consecutive consciousness-impaired patients with their short-term outcome is presented.