Single photon emission computerized tomography (SPECT) in detecting neurodegeneration in Huntington's disease.

Single photon emission computerized tomography (SPECT) studies were performed on 34 manifest Huntington's disease (HD) patients at various stages of clinical pathology ranging from early chorea to late dystonia with or without signs of dementia and 12 pre-symptomatic patients with abnormal terminal CAG expansions. Thirty HD patients with obvious clinical signs and seven pre-symptomatic patients without signs or symptoms of HD displayed selective caudate hypoperfusion by direct visual inspection. Such qualitative, selective striatal hypoperfusion patterns can be indicative of early and persistent metabolic changes in striatal neuropathology. SPECT studies can be useful in documenting early pre-clinical changes in patients with abnormal terminal CAG expansions and in confirming the presence of caudate pathology in patients with clinical signs of HD.

DNA testing and genetic counseling: truth or consequences.

Advances in medical genetics are providing a major clinical challenge to practitioners seeing patients concerned about their risk of developing either inherited disease or susceptibility to acquired disease. Popular information can easily exceed our professional ability to provide services to well-read patients who want answers with scientific certainty. The challenge also involves ethical questions regarding confidentiality and the way that results are disclosed. More often than not, the test itself becomes the focus of psychosocial expectations for the future and lifestyle of the patient and family. The behavioral consequences of disclosure of test results need to be anticipated by the caregiver to avoid adverse psychological outcomes.

Visuospatial judgment and right hemisphere disease.

The performances of patients with stroke-produced unilateral hemispheric lesions on a test requiring the identification of lines were examined in the light of a recent report that contradicted previous observations. The study confirmed the results of earlier studies that patients with lesions of the right hemisphere show a remarkably high frequency of defective performances while those with lesions of the left hemisphere do not. Possible reasons for findings that deviate from this rule are discussed.

Hemisphere asymmetry in decision making abilities. An experimental study in unilateral brain damage.

Thirty control subjects and 60 unilateral brain-damaged patients, 30 with left hemisphere (LH) damage and 30 with right hemisphere (RH) disease, underwent a disjunctive 4-choice reaction time study. Speed of reaction (as defined by the reciprocal of reaction time (RT), movement time (MT) and total response time (TRT] and accuracy of response (as represented by the sum of errors in selecting the correct response key) were investigated comparatively as a function of side of lesion and of performance on Raven's Coloured Progressive Matrices (PM47). In contrast to movement speed (1/MT), reaction speed (1/RT) as well as total response speed (1/TRT) showed a lesion effect independent of side of damage. Conversely, accuracy was differentially impaired, LH damage being associated with a significantly higher number of errors. Speed and accuracy had different relationships with the performance on the PM47 in the two hemisphere groups. Speed was affected in parallel with changes in PM47 performance both in the LH and in RH groups, whereas accuracy was altered only in LH patients. It was concluded that speed of motor reaction is affected by unilateral brain lesions irrespective of their side, whereas decision making processes, as expressed by accuracy of response, seem to be specifically impaired by LH damage.

Constructional praxis performance of Japanese and American, normal and brain-damaged patients.

Numerous studies have suggested population differences between Japanese and Americans concerning various cognitive functions. Transcultural differences in spatial reasoning, language, and dominance for emotional expression raise important questions concerning current conceptions of hemispheric cerebral dominance for cognitive functioning. If cultural differences in cognition exist, learning may play a greater role in determining laleralizalion of cognitive functions than is presently accepted. To investigate these issues, we initiated two collaborative studies comparing Japanese with American normals and brain-damaged patients on the Three-Dimensional Constructional Praxis Test. In normal subjects, there were no significant differences between the two cultures in the distribution of visuoconstructive ability. In patients with brain damage, the effects of unilateral brain lesions and their neuropsychological consequences on visuoconstructive ability were similar in both cultures. Thus, there are no apparent differences between the Japanese and American peoples in visuoconstructive abilities, or in the underlying cerebral organization of skills required to execute these functions.

Presidents Test performance in varieties of diffuse and unilateral cerebral disease.

Two studies addressed issues concerning the validity of the Presidents Test. The results of Study 1 substantiated that generalized impairment for recent presidents occurs frequently in the context of multifocal and diffuse cerebral disease. Performances of normal elderly (n = 31) on all four Presidents subtests were superior to those of patients with confusional states (n = 7), uncomplicated dementia (n = 24), and dementia with confusion (n = 20). Overall, 88% of the combined sample was correctly classified (control v. diffuse cerebral disease). In Study 2, generalized memory impairment for recent presidents was found to be rare among samples of patients with unilateral right- and left-hemisphere lesions (n = 40 each). A selective impairment in temporal sequencing was preferentially associated with right-hemisphere disease, whereas verbal deficit patterns were more common in patients with left-sided lesions. These findings further document the validity of the Presidents Test as an efficient, objective method for assessing recent memory impairment due to widespread cerebral disease and suggest that qualitative analysis of performance patterns may be useful for detecting certain nonmnemonic cognitive defects in patients with focal brain disease.

Neuropsychological findings in toxicometabolic confusional states.

Patients with acute confusional states display impaired attention and memory with difficulty following complex verbal commands. In addition to these deficits, we have observed a selective impairment in spatial thinking similar to that present following right-hemisphere lesions. Consequently, we compared patients with acute confusional states (CS) to patients with focal right-hemisphere disease (RHD) and controls on a standard neuropsychological battery. Although impaired relative to controls, both CS and RHD groups did not differ from each other on those tests typically associated with right-hemisphere lesions. These included performance IQ, constructional praxis, spatial judgment, and cancellation tasks. In light of these findings, the neurological correlates of selective deficits in spatial processes include not only unilateral right-hemisphere lesions, but also diffuse disorders such as CS. Thus, there is the potential to misinterpret the neuropsychological test results of patients with diffuse cerebral disorders as indicating focal abnormalities when none exist.

Memory for recent U.S. presidents in patients with cerebral disease.

Four tasks were developed to assess memory for recent U.S. presidents: free recall of presidents' names, naming their photographs, and temporal ordering of their printed names and photographs. The tasks were standardized on a sample of 250 hospital control subjects and administered to 55 patients with cerebral disease. Recall of the presidents' names, a task frequently advocated for mental status examination, was relatively difficult for hospital control patients and was least sensitive to brain disease. None of the brain-damaged patients manifested an isolated retrieval defect. Generalized memory impairment for recent presidents was not found with focal lesions. In the context of a diffuse or bilateral disease, generalized memory impairment for recent presidents was a frequent concomitant of substantial intellectual loss. This brief, multi-task assessment of memory for recent presidents may prove a more useful adjunct to neurobehavioral evaluation than testing simple recall of presidents' names.

Effects of minority status on facial recognition and naming performance.

Found performances on two tests of higher cerebral function, a facial recognition test and a naming test in an aphasia examination, to be influenced differentially by minority status (N = 94). Performance on the facial recognition test was relatively free of racial bias for the purposes of clinical assessment, but this was not the case for visual naming. In fact, straightforward application of the standard criteria for the naming test would have resulted in classification of 22% of a sample of urban black control patients as defective. Revised normative standards are presented for use in this segment of the referral population.

Mental status examination in Alzheimer's disease. The neuropsychologist's role.

The neuropsychologic consultant can offer an objective and comprehensive method of documenting the mental status of patients being evaluated for dementia. The neurobehavioral examination is an extension and elaboration of the bedside mental status examination, with added methods of controlling for various background factors that can influence performance on cognitive testing. In dementia, the cognitive findings appear to have a close association with the underlying neuropathologic changes and mortality. This makes the neurobehavioral examination useful in differentiating dementia from other neurologic and psychiatric conditions when the clinical diagnosis is uncertain.

Prediction of outcome in anorexia nervosa from neuropsychological status.

To evaluate the possibility that subtle brain dysfunction may exist in anorexia nervosa and indicate a poor prognosis, 20 anorexia nervosa patients received neuropsychological assessments covering a broad array of cognitive performances. The patients were examined at admission and again at the end of an inhospital treatment program when they were at normal weight for their age and height. Pretreatment performance on the assessment battery was not associated with outcome 1 year after discharge. However, posttreatment performance and significantly associated with outcome. A majority (71%) of patients with two or more cognitive deficits showed an unfavorable outcome (i.e., did not maintain their weight). In contrast, a majority (85%) of patients with less than two cognitive defects had a favorable outcome (i.e., maintained or increased their weight). The findings suggest that the hypothesis of a central nervous system disorder limiting the capacity for anorectics to recover deserves further exploration.

Facial recognition in patients with focal brain lesions.

The performances of patients with radiologically or surgically verified focal lesions on a test requiring the identification of unfamiliar faces were investigated. Nonaphasic patients with posterior right hemisphere lesions and aphasic patients with substantial impairment in language comprehension showed a notably high frequency of defect. The frequency of defective performance in nonaphasic patients with right anterior lesions was higher than normal but less than that of the previously mentioned groups. Nonaphasic patients with left hemisphere lesions and aphasic patients without substantial impairment in language comprehension performed on a level comparable with that of control subjects. It is concluded that the identification of unfamiliar faces is a bihemispheric process, possibly involving linguistic as well as visuoperceptive components.

Visuospatial judgment. A clinical test.

We constructed and developed a brief test assessing capacity for discriminating the direction of lines. Application of the test to patients with unilateral brain disease disclosed a remarkably high frequency of defective performance in those with right hemisphere lesions. The performance of patients with left hemisphere lesions was comparable to that of control patients. Brevity and ease of administration make the test convenient for clinical use.

Depression and hemispheric functions: changes associated with unilateral ECT.

Nine depressed patients received ECT to the dominant (left) side along with nine matched depressed patients who received ECT to the non-dominant (right) side. Neuropsychological tests showed that the right hemispheric functions were more frequently abnormal as compared to left hemispheric (dominant) functions in the pre-ECT tests. ECTs delivered to either the right or left side improved right hemispheric functions when the depression was ameliorated. This study indicates that in depression right hemispheric functions are initially disturbed and ECT, instead of being deleterious to these functions, tends to improve them.

Stereopsis and unilateral brain disease.

Performance on a random-letter stereoscopic task has been reported to be affected by right but not left cerebral disease. Subsequent studies employing a conventional stereoacuity test have challenged these results and proposed that dementia may be the primary determinant of impaired stereopsis in the patients with brain disease. The latter investigators have failed to distinguish between local and global stereopsis. The present study confirms the original findings, rules out dementia as a potential artifact, and attempts to reconcile the conflicting series of reports.

Spontaneous recovery in rabbit eyelid conditioning.

Spontaneous recovery of the classically conditioned rabbit eyelid response increased in a negatively accelerated function with an increase of postextinction rest from .17 to 24 hr. The data were obtained from six groups of male New Zealand rabbits which received an extinction session separated by rest intervals of varying duration from a spontaneous recovery test.

Interactive effects of age and cerebral disease on cognitive performances.

A battery of mental tests was given to groups of younger (16--44 years) and older (48--60 years) control and cerebral diseased patients. Each patient in the younger cerebral diseased group was matched individually with an older cerebral diseased patient for type and site of lesion. Each patient with cerebral disease was matched individually with a control patient for age, educational level and sex. Differences in level of test performance related to age were generally greater for cerebral diseased than for control patients. Differences in level of test performance related to diagnostic category were generally greater for older than for younger patients. Analysis disclosed a significant overall interactive effect of age and cerebral disease on the performance of mental tests, supporting the hypothesis that acquired cerebral disease has more severe behavioral consequences in older than in younger persons.