Neuropsychiatry, neuropsychology, and behavioral neurology最新文献

Objective: To study the relationship between peripheral autonomic arousal and emotional experience.

Background: Several theories of emotional experience suggest that this experience is, at least in part, related to feedback from the viscera and the autonomic nervous system.

Method: To partially test this hypothesis and to learn if there are hemispheric asymmetries of emotional experience, we studied skin conductance responses (SCR) and verbal report in patients with right hemisphere damage (RHD), patients with left hemisphere damage (LHD), and normal control subjects during the anticipation of electric shocks.

Results: During the shock condition, RHD and LHD subjects had smaller SCRs than did normal control subjects. Verbal report measures, however, revealed that subjects reported feeling less pleasant, more aroused, and less in control during the shock condition compared to the no-shock condition. Unlike the SCR results, the verbal report of emotional experience did not differ between the patients with RHD, patients with LHD, and normal control subjects.

Conclusions: Emotional experience is not dependent upon activation of and feedback from the autonomic nervous system.

Objective: Early information processing deficits are consistently reported for patients with schizophrenia. A growing number of studies have applied a transient (magnocellular) or sustained (parvocellular) explanation to account for deficient processing of briefly presented visual stimuli, moving stimuli, and stimuli requiring eye movements in patients with schizophrenia. This reasoning is based on research that makes the distinction between a magnocellular channel, which primarily responds to low spatial frequency and moving or rapidly presented visual information, and a parvocellular channel, which is primarily responsive to high spatial frequency and detailed information.

Background: Although the preponderance of findings offer support for transient ("where is it") as opposed to sustained ("what is it") deficit in patients with schizophrenia, there remains a need for more specific depiction of the deficit.

Method: The present study evaluated normal control subjects and patients with schizophrenia recruited from in-patient and out-patient settings. A Motion Defined Letter task was used, owing to its sensitivity to transient (magnocellular) activation.

Results: Twenty-three patients with schizophrenia and sixteen normal control subjects were tested on eight dot velocity levels, ranging from 88 arc min/sec to 0.69 arc min/sec. A repeated measures analysis of variance indicated that the performance of patients with schizophrenia was significantly poorer than that of their normal counterparts on the three fastest dot velocity conditions (88 arc min/sec, p < 0.0001, 44 arc min/sec, p < 0.00001, and 22 arc min/sec, p < 0.00003), but performance did not differ on the five slower dot velocity conditions. A regression analysis revealed that the dosage of medication was positively associated with performance on three middle range dot velocity conditions (11 arc min/sec F (1,22) = 6.99; p < 0.025; 5.5 arc min/sec, F (2,20) = 0.379; p = 0.05, and 2.25 arc min/sec F (2,20) = 7.37; p < 0.005).

Conclusions: The findings afford support for an early information processing deficit in schizophrenics. These data also support the neurophysiologic model that explains the poor performance of patients with schizophrenia as it relates to a transient channel deficiency.

Objective: To provide an update of the neurobiologic basis of human immunodeficiency virus (HIV)-associated dementia (HAD), with emphasis on the relationship between dopamine (DA) system dysfunction and behavioral manifestations.

Background: HIV has a propensity to invade subcortical central nervous system areas, particularly the basal ganglia. Indeed, the core symptoms of HAD are similar to those seen in patients with frontal-striatal dysfunction, the "subcortical dementias" (e.g., Parkinson disease, Huntington disease, progressive supranuclear palsy).

Findings: Damage to DA neurons appears to occur in early stages of the disease. Patients with HIV have decreased levels of cerebrospinal fluid DA, and patients with HAD have a reduction of the DA metabolite homovanillic acid but a relative preservation of other neurotransmitters, suggesting a loss of DA neurons. Neuropathologic examinations have shown neuronal loss of the globus pallidus, which is less severe in the neocortex. Furthermore, extrapyramidal signs and marked hypersensitivity to DA antagonists (e.g., neuroleptics) have a propensity to develop in patients with acquired immunodeficiency syndrome.

Conclusions: Neurobiologic investigations suggest that DA system dysfunction plays a critical role in the clinical manifestation of HIV infection, especially HAD. The causes of the vulnerability of this system to the infection are unknown. Understanding this mechanism is important to develop neuroprotective agents in the treatment of HAD and to design new therapies for HAD-related psychiatric symptoms.

Objective: To examine neuropsychologic functions in patients with chronic obstructive pulmonary disease (COPD) and mild hypoxemia compared with patients with mild Alzheimer disease and normal controls.

Background: Cognitive deficits have been documented in patients with COPD, but few studies have compared the neuropsychologic status of these patients with that of other neurologic groups.

Method: Cognitive test results from 32 patients with COPD and mild hypoxemia (mean age, 70.3 years; mean education, 13.2 years; mean partial arterial oxygen pressure, 68.8 mm Hg) who had no neurologic symptoms were compared with 31 subjects with mild Alzheimer disease (AD) and 31 normal controls similar in age, education, and sex. Seventy-three percent of the patients with COPD were receiving supplementary oxygen.

Results: Significant group differences across 11 cognitive scores were found using analysis of variance, and post hoc analyses indicated that patients with mild AD performed significantly worse than normal controls and patients with COPD on most tests. The group with COPD and the group with AD demonstrated lower letter fluency compared with controls. Although the patients with COPD performed significantly worse than controls on verbal fluency tasks, they were not in the clinically impaired range, and, overall, the group with COPD was similar to the controls on most cognitive tests.

Conclusions: These findings suggest that many patients with COPD and mild hypoxemia who don't have neuropsychiatric histories may perform normally on cognitive measures. Oxygen therapy may partially account for preservation of cognitive function in these patients. Results also suggest that patients with COPD and normal controls can be readily distinguished from patients with mild AD based on levels and patterns of neuropsychologic test results. Any significant cognitive deficits in patients with mildly hypoxemic COPD may warrant continued neurologic evaluation.

Background/objective: Grapheme-to-phoneme conversion (GPC) allows the pronunciation of nonword letter strings and of real words with which the literate reader has no previous experience. Although cross-modal association between visual (orthographic) and auditory (phonemic-input) representations may contribute to GPC, many cases of deep or phonologic alexia result from injury to anterior perisylvian regions. Thus, GPC may rely upon associations between orthographic and articulatory (phonemic-output) representations.

Method/results/conclusion: Detailed analysis of a patient with phonologic alexia suggests that defective knowledge of the position and motion of the articulatory apparatus might contribute to impaired transcoding from letters to sounds.

Objective: To assess the relationship between denial of memory deficit and dementia severity in patients with Alzheimer disease (AD). Additionally, to introduce a new instrument, the Awareness of Memory Impairment Scale (AMIS), devised to minimize biases present in previous studies, especially those attributable to the use of difference scores and clinical ratings.

Background: Estimates of the magnitude of denial in patients with AD, and of its relationship with disease progression, have varied across studies. Part of this variability may have resulted from differences in the way investigators measured denial. In this study, the AMIS was used to obtain a relatively unbiased assessment of the relationship between denial and disease severity in patients with AD.

Method: Two hundred three patients with AD were studied, 106 longitudinally, and 40 age-matched control subjects were evaluated. Multiple regression analysis, controlled for age, sex, education, and duration of illness, was used to compare AMIS scores with disease severity cross-sectionally and to determine whether AMIS scores change over time. A similar analysis was performed using difference scores and clinical ratings to determine whether introduction of a new assessment instrument was warranted.

Results: Cross-sectionally, a small but statistically significant correlation between AD denial and dementia severity was found. Upon direct longitudinal assessment, no change in denial was noted after a mean interval of 1 year and 3 months. As expected, use of difference scores and clinical ratings yielded inflated correlations relative to those obtained with the AMIS.

Conclusions: Denial of memory deficit correlates minimally with dementia severity in cross-sectional analysis but is independent of disease progression when assessed longitudinally.

Objective: To describe a patient who exhibited a partial Klüver-Bucy syndrome after small bilateral ischemic lesions in the thalami.

Background: Previously reported patients with Klüver-Bucy syndrome had very large, mostly bilateral lesions in the limbic system and could not provide sufficient information about its anatomo-functional correlate.

Method: Behavioral assessments and clinical examinations, including magnetic resonance imaging and positron emission tomography, were conducted.

Results: The patient was severely amnestic, distractible, hyperoral, and affectively dyscontrolled, and she behaved socially inappropriately. Magnetic resonance imaging showed bilateral infarctions in the territories of both thalamoperforating arteries, and positron emission tomography revealed bilaterally decreased fluorodeoxyglucose uptake in the anterior parts of the ventral thalami and, to a lesser extent, in the fronto-temporal cortices.

Conclusions: This behavioral syndrome has not yet been reported with isolated diencephalic lesions, but it has been observed after bilateral temporal lobe lesions. The authors conjecture that this syndrome resulted from a disruption of the pathways connecting the dorsomedial thalami with the prefrontal cortices and with other limbic areas, systems essential for memory and the regulation of impulses and emotions.

Objective: To examine the effects of prenatal or perinatal stroke on the facial recognition skills of children and young adults. It was hypothesized that the nature and extent of facial recognition deficits seen in patients with early-onset lesions would be different from that seen in adults with later-onset neurologic impairment.

Background: Numerous studies with normal and neurologically impaired adults have found a right-hemisphere superiority for facial recognition. In contrast, little is known about facial recognition in children after early focal brain damage.

Method: Forty subjects had single, unilateral brain lesions from pre- or perinatal strokes (20 had left-hemisphere damage, and 20 had right-hemisphere damage), and 40 subjects were controls who were individually matched to the lesion subjects on the basis of age, sex, and socioeconomic status. Each subject was given the Short-Form of Benton's Test of Facial Recognition. Data were analyzed using the Wilcoxon matched-pairs signed-rank test and multiple regression.

Results: The lesion subjects performed significantly more poorly than did matched controls. There was no clear-cut lateralization effect, with the left-hemisphere group performing significantly more poorly than matched controls and the right-hemisphere group showing a trend toward poorer performance. Parietal lobe involvement, regardless of lesion side, adversely affected facial recognition performance in the lesion group. Results could not be accounted for by IQ differences between lesion and control groups, nor was lesion severity systematically related to facial recognition performance.

Conclusions: Pre- or perinatal unilateral brain damage results in a subtle disturbance in facial recognition ability, independent of the side of the lesion. Parietal lobe involvement, in particular, has an adverse effect on facial recognition skills. These findings suggest that the parietal lobes may be involved in the acquisition of facial recognition ability from a very early point in brain development, but that there is sufficient potential to reorganize or compensate such that the residual deficits, though significant, are subtle.

Objective: To examine the role of structural (magnetic resonance imaging [MRI]) and functional (single photon emission computed tomography [SPECT]) imaging and neuropsychologic evaluation in the early diagnosis of frontal variant frontotemporal dementia (fvFTD).

Background: Current criteria for FTD stress the need for neuropsychologic and functional neuroimaging abnormalities, yet caregivers report lengthy histories of behavioral change. It is not known when, in the course of the disease, these investigations become abnormal, because few longitudinal studies have been reported.

Method: Longitudinal study of two patients with serial neuropsychologic evaluation and MRI and HMPAO-SPECT scanning.

Results: Both patients, men aged 49 and 50, had major changes in personality, behavior, and social conduct that progressed over 5 to 6 years in a way that conformed to the clinical picture of fvFTD. There was remarkably little abnormality on neuropsychologic testing, and MRI and HMPAO-SPECT findings initially were normal. Over time, however, abnormalities on SPECT, frontal atrophy on MRI, or a neuropsychologic profile more typical of fvFTD developed in both patients.

Conclusions: Standard neuropsychologic tests and conventional brain imaging techniques (MRI and SPECT) may not be sensitive to the early changes in fvFTD that occur in the ventromedial frontal cortex, and better methods of accurate early detection are required. These findings are relevant to the diagnostic criteria for FTD.