Neuropsychiatry, neuropsychology, and behavioral neurology最新文献

Objective: This study was designed to determine whether young and older adults differ in the spatial pattern of omission errors on random-array letter cancellation tasks.

Background: Aging is associated with declines in the speed or efficiency of visual information processing. It is unclear whether the spatial characteristics of visual exploration also change with aging.

Method: Thirty young adults and 30 older adults each completed 21 random-array cancellation forms. Forms were systematically varied in paper size, target-to-distractor ratio, stimulus density, and target number.

Results: The spatial distribution of errors was not random for older adults. Younger adults expressed a trend toward nonrandom error location, but the spatial distribution did not differ between groups. There was also a strong trend toward more errors per subject in the older group. Older subjects required more time for task completion.

Conclusions: The findings are consistent with a generalized age-related decline in the speed or efficiency of visual search, but the spatial properties of directed attention do not appear to be different between young and older adults.

Objective: The objective of this study was to investigate cerebral asymmetries for the detection of brief temporal events in a group of 22 dextrals using psychophysical measures.

Background: By combining electrophysiologic and psychophysical measures, it should be possible to demonstrate that the right ear advantage reported in previous studies is the result of a left hemisphere temporal processing advantage rather than a rightward attentional bias.

Method: Bursts of white noise lasting 300 milliseconds were delivered unilaterally to the participants' ears. Half of the stimuli contained a gap lasting either 4 or 6 milliseconds. Participants indicated whether or not the noise burst contained a gap. Asymmetries in alpha and beta activity at left and right temporal lobe sites were measured during the task.

Results: The psychophysical data confirmed previous reports of faster response times (RTs) and lower levels of error for the right ear (RE). There was no asymmetry in alpha activity between the left and right temporal lobes; however, there was a higher level of beta activity in the left temporal lobe.

Conclusions: The electrophysiological data suggest that the perceptual asymmetry is not the result of a nonspecific rightward attentional bias but that of a left hemisphere specialization for the detection of brief temporal events. The relation between atypical temporal processing asymmetries and developmental learning disorders is discussed.

Objective: To better understand apathy and disengagement in patients with Alzheimer's disease (AD), the authors investigated possible behavioral mechanisms underlying diminished novelty-seeking activity in patients with probable AD.

Background: Apathy and disengagement have been shown to be the most common behavioral changes associated with AD.

Method: Patients and age-matched normal controls had their eye movements recorded while pairs of line drawings pitting an incongruous figure against a congruous figure were shown on a screen for 12 seconds. Characteristics of a subset of AD patients who were indifferent to novel visual stimuli as measured by exploratory eye movements were compared to those of a subset of AD patients who were attracted to novel stimuli to a degree similar to that of normal controls.

Results: The indifferent patients were judged by informants, who completed a personality questionnaire, to exhibit a greater degree of apathy. The two AD groups did not differ in overall dementia severity or performance on a Saccade-to-Target Task that required shifts of attention and gaze. In a separate task, the indifferent patients were able to accurately identify the more novel stimuli in 97.5% of trials. Normal control subjects exhibited a strong bias toward processing novel stimuli, directing a higher proportion of their first fixations and dwell time to the incongruous stimuli whether the analysis was run for 3, 6, or 12 seconds of viewing. Indifferent patients did not direct their initial fixation toward novel stimuli and distributed their looking time evenly between incongruous and congruous stimuli throughout all measured intervals.

Conclusions: The results suggest that the indifference to novelty observed in some patients with probable AD cannot simply be attributed to global cognitive decline, more elementary attentional deficits, more rapid habituation of response to novel stimuli, or an inability to discriminate upon demand between stimuli of varying degrees of novelty. It is more likely that their behavior reflects a disruption, by AD pathology, of neural systems that modulate behavioral engagement and maintain attentional bias toward novel events in the environment.

Objective: This study attempted a systematic investigation of incidence, type, and circumstances of anomalous perceptual experiences in a highly specialized group of healthy subjects, extreme-altitude climbers.

Background: There is anecdotal evidence for a high incidence of anomalous perceptual experiences during mountain climbing at high altitudes.

Method: In a structured interview, we asked eight world-class climbers, each of whom has reached altitudes above 8500 m without supplementary oxygen, about hallucinatory experiences during mountain climbing at various altitudes. A comprehensive neuropsychological, electroencephalographic, and magnetic resonance imaging evaluation was performed within a week of the interview (8).

Results: All but one subject reported somesthetic illusions (distortions of body scheme) as well as visual and auditory pseudohallucinations (in this order of frequency of occurrence). A disproportionately large number of experiences above 6000 m as compared to below 6000 m were reported (relative to the total time spent at these different altitudes). Solo climbing and (in the case of somesthetic illusions) life-threatening danger were identified as probable triggers for anomalous perceptual experiences. No relationship between the number of reported experiences and neuropsychological impairment was found. Abnormalities in electroencephalographic (3 climbers) and magnetic resonance imaging (2 climbers) findings were likewise unrelated to the frequency of reported hallucinatory experiences.

Conclusions: The results confirm earlier anecdotal evidence for a considerable incidence of hallucinatory experiences during climbing at high altitudes. Apart from hypoxia, social deprivation and acute stress seem to play a role in the genesis of these experiences.

Objective: Distinguishing early dementia from normal aging is especially difficult in patients with higher than average intellectual abilities. To find signs useful in determining that the elderly "worried and well" are not in an early phase of dementia, we compared the neuropsychological test performance of demented patients, patients who were not found to be demented, and control subjects.

Method: A retrospective study of neuropsychological test results from persons over 50 years of age who had an age-adjusted verbal intelligence quotient (VIQ) greater than or equal to 110. Analysis of covariance (using age and education as covariates) was used to compare the normal, no dementia, and dementia groups. Significant differences were further analyzed using Tukey's post hoc procedure. Tests on which the three groups differed at ap < 0.01 level were included in multivariate analyses.

Results: The no dementia patient group performed at functional levels comparable to those of the control group. By contrast, patients with dementia showed significant impairment on tests of memory, naming, and visuospatial function compared with both the control and no dementia groups. Immediate and delayed paragraph recall classified groups with a 96% specificity and 80% sensitivity in the multivariate discriminant analysis.

Conclusions: These results suggest that in patients with higher than average intelligence, the absence of a significant dementing process (as well as its presence) can be determined with reasonable probability.

Objective: To examine observers' initial affective impressions of unilateral stroke patients, based on exposure to the patients' verbal and nonverbal behavior. Given the linguistic deficits associated with left hemisphere damage (LHD), the authors expected affective judgments based on exposure to patients' utterances to be reduced for patients with LHD. Given the nonverbal deficits associated with right hemisphere damage (RHD), the authors expected affective judgments based on exposure to patients' facial expressions to be reduced for patients with RHD.

Method: Ten patients with LHD, 11 patients with RHD, and seven normal control (NC) patients were videotaped while engaging in social interaction. Observers read transcripts of the interactions and made judgments about how much they liked the patients. They then watched soundless videotapes and made similar liking judgments. This reflected a 3 (patient group) x 2 (coding modality) mixed factorial design.

Results: A 2 x 3 analysis of variance yielded a significant interaction. When liking judgments were based on utterances, patients with LHD were liked less than patients with RHD and NC patients. When liking judgments were based on facial expressions, patients with RHD were liked less than patients with LHD and NC patients.

Conclusions: The verbal behavior of patients with LHD and the nonverbal behavior of patients with RHD may affect others' impressions of them, and consequently put these patients at interpersonal risk.

In the history of evolution, biologic organisms have formed traits with both adaptive and sometimes maladaptive significance to their surrounding environments. The sickle cell mutation genes conferring resistance to malarial infection in human heterozygotes is an example of how certain genetic abnormalities can serve adaptive significance to an organism. Schizophrenia and the "Odyssyian personality" have often been cited as a neuropsychiatric correlate for evolutionary adaptive benefit in an organism. This article re-examines the possibility that schizophrenia-related genes can serve a beneficial adaptive role and that altered function of the N-methyl-D-aspartate receptor is the molecular correlate of such adaptive significance.

Objective: This case provides data from serial assessments using a comprehensive neuropsychological test battery to assess the effects of severe toxicity on cognitive functioning, the pattern of deficits, and the regions of the brain that appear to be involved.

Background: Lithium carbonate has made a significant contribution to the treatment of bipolar disorder, and considerable investigation has been conducted on both temporary and long-term side effects on the central nervous system. The effects of acute lithium intoxication on the central nervous system have been extensively documented.

Method: We studied a severe case of acute lithium intoxication and associated neuropsychological sequelae. The patient was evaluated twice with a comprehensive battery of neuropsychological tests within 2 years of the lithium intoxication.

Results: Comprehensive neuropsychological evaluations indicated persistent cognitive sequelae, including impaired memory, attention, executive control functions, and visuospatial deficits.

Conclusions: The cognitive sequelae noted in the case of lithium toxicity are consistent with a subcortical dementia and the findings of other authors. Findings should be explored further in more rigorous clinical studies.

Objective: The validity of supplementing the three-item recall portion of the Mini-Mental State Examination (MMSE) with a cued recall procedure to help specify the nature of patients' memory problems was examined.

Method: Subjects were 247 individuals representing three diagnostic groups: Alzheimer's disease (AD), subcortical vascular ischemic dementia (SVaD), and normal controls. Individuals were administered a battery of neuropsychological tests, including the MMSE, as part of a comprehensive evaluation for the presence of dementia or other neurologic disorder.

Results: MMSE performance differed among groups. The three-item free recall performance also differed among groups, with post hoc analyses revealing the AD and SVaD groups were more impaired than controls but did not differ significantly from each other. Following a cued recall procedure of the MMSE three-items, groups differed, with post hoc analyses showing that AD patients failed to benefit from cues, whereas SVaD patients performed significantly better and comparable to control subjects. Significant correlations between the MMSE three-item cued recall performance and other memory measures demonstrated concurrent validity.

Conclusions: Consistent with previous research indicating that SVaD is associated with memory encoding and retrieval deficits, whereas AD is associated with consolidation and storage problems, the present study supported the validity of the cued recall procedure of the three items on the MMSE in helping to distinguish between patients with AD and those with a vascular dementia with primarily subcortical pathology; however, despite these findings, a more extensive battery of neuropsychological measures is still recommended to consistently assess subtle diagnostic differences in these memory processes.

Objective: The objective of this study was to compare psychometric profiles of Alzheimer's disease (AD) patients with subcortical magnetic resonance imaging (MRI) signal abnormalities to those of AD patients without such MRI findings (normal subcortical MRI) and to those of patients with ischemic vascular dementia (IVD) associated with small and primarily subcortical ischemic changes.

Background: The cognitive significance of MRI white matter and other subcortical abnormalities in AD is unknown. Prior studies comparing AD patients with white matter changes on MRI have not included IVD patients with comparable MRI findings. If white matter/subcortical changes in AD reflect vascular abnormalities, they might be associated with cognitive profiles similar to those seen in subcortical IVD.

Method: We studied 15 AD patients with normal subcortical MRIs, 22 AD patients with subcortical MRI hyperintensities, and 18 IVD (NINCDS-ADRDA and NINDS-AIREN criteria) at the Alzheimer's Disease Research Center of the Baylor College of Medicine. IVD patients had predominantly small and subcortical signal abnormalities, and none had large cortical infarcts. AD patients had only nonspecific subcortical signal abnormalities with or without atrophy (atrophy was not analyzed). We compared the AD group with abnormal MRIs to the AD group with normal subcortical MRIs and the AD group to the IVD group using ANCOVA planned comparisons (dementia severity and education covaried).

Results: AD patients with abnormal MRIs did not differ significantly from AD patients with normal subcortical MRIs on any of the neuropsychological measures. AD patients exhibited significantly better attention/concentration, visuospatial/visuoconstructional performance, letter fluency, motor programming, and simple motor speed than IVD patients as well as significantly worse delayed verbal recognition memory. Because MRI changes were generally more extensive in IVD, a subset of AD patients with abnormal subcortical MRIs was compared to a subset of IVD patients matched for degree of MRI signal abnormalities. These subsets of AD and IVD patients still showed distinctive neuropsychological profiles.

Conclusions: AD patients with or without MRI subcortical signal abnormalities have similar neuropsychological profiles, and they differ from IVD patients with comparable MRI changes. Although MRI signal abnormalities in AD patients who have no history or examination findings of cerebrovascular disease overlap with those seen in IVD patients, they do not seem to have the same cognitive significance. Periventricular hyperintensities (PVHs) and deep signal hyperintensities, especially those of a mild to moderate degree, may reflect a different pathophysiologic process in AD than in IVD and do not necessarily have cognitive consequences in AD patients.