Postoperative cognitive dysfunction: overinterpretation of data?
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A computerized version of the object alternation test (OAT) was employed in unmedicated obsessive-compulsive disorder (OCD) patients and matched healthy controls. OCD patients performed normally on the OAT but scored below controls on a task assessing visuo-spatial working memory. The results challenge the concept of the OAT as a sensitive instrument for orbitofrontal dysfunction in OCD.
BACKGROUND: With the use of comprehensive neuro-psychological assessments, a substantial proportion of patients with multiple sclerosis have been found to have substantial cognitive impairment. Although data generated from comprehensive examinations are useful in making recommendations for treatment interventions and compensatory strategies, the cost of such assessments prohibits their use with all patients. OBJECTIVE: To develop a screening battery to detect cognitive impairment in patients with multiple sclerosis that is sensitive, specific, brief, and cost-effective, and could identify patients who might benefit from a more comprehensive neuropsychological examination. DESIGN: On the basis of a comprehensive neuropsychological assessment battery, the presence of significant cognitive impairment was determined in patients with multiple sclerosis. The screening battery consisted of a subset of tests from the comprehensive battery. Performance on the screening battery was then used to predict presence of cognitive impairment on the comprehensive battery in validation and cross-validation samples. Severity of impairment on the screening battery was also regressed on ratings of functional impairment derived from the Expanded Disability Status Scale. RESULTS: In the validation sample, the screening battery had 100% sensitivity, 80% specificity, and 88.1% overall diagnostic accuracy. In the cross-validation sample, the screening battery had 100% sensitivity, 81.8% specificity, and an overall diagnostic accuracy rate of 90.7%. chi 2 tests showed that the accuracy of the screening battery was significantly better than chance in both samples. Performance on the screening battery also predicted the level of disability ratings on the Expanded Disability Status Scale and functional systems scales. CONCLUSIONS: The screening battery had a high degree of sensitivity, specificity, and diagnostic accuracy, while maintaining a brief administration time and high cost-effectiveness. The screening battery also predicted higher levels of disability and functional impairment as assessed by the Expanded Disability Status Scale, thereby enhancing its clinical utility. Despite its advantages, the findings do not suggest that the screening battery may be an effective substitute for a more detailed examination.
Impairment of executive-frontal lobe functioning, affecting the planning, initiation and regulation of goal-directed behavior, is a common cognitive deficit in schizophrenia. However, it is unclear if deficits in these frontal-lobe-mediated abilities are differentially expressed across clinical subgroups. We analyzed executive-frontal abilities in relation to symptom expression in 53 hospitalized schizophrenic patients. Patients were assigned to one of three subgroups based on rank order analysis of Brief Psychiatric Rating Scale factors: Withdrawal-Retardation, Reality Distortion and Conceptual Disorganization. Executive-frontal tests included Visual Search, Verbal Fluency, Verbal Series Attention, Trail Making - Part B, Symbol Digit, Hopkins Verbal Learning, Digit Span, Wisconsin Card Sorting, Stroop Color-Word and Attentional Capacity. The schizophrenia group showed significant deficits relative to healthy control subjects (n = 20) on all tests. Exploratory factor analysis of test scores revealed three factors: (i) Verbal Processing/Memory; (ii) Cognitive Flexibility/Attention; and (iii) Psychomotor Speed/Visual Scanning. The three symptom subgroups were differentially impaired on executive-frontal abilities: Withdrawal-Retardation on psychomotor speed, verbal fluency, working memory, visual search and cognitive flexibility; Conceptual Disorganization on attention; Reality Distortion on verbal memory. The results have implications for syndrome definition, pharmacological intervention and prediction of outcome in schizophrenia.
Behavioral similarities between antisocial behavior disorders and frontal-lobe cerebral impairment have led to suggestions that conduct disorders are attributable to disinhibition deficit associated with frontal-lobe cerebral functions. This study compared the performance of 21 conduct disorder adolescents on measures of cognitive processes associated with frontal-lobe functions with that of a matched comparison sample. Conduct disorder adolescents performed more poorly on measures sensitive to frontal-lobe dysfunction (conceptual perseveration, poorly sustained attention, impaired sequencing on memory and motor tasks), but not on non-frontal-lobe specific cognitive measures. Although the findings support a neurobehavioral explanation of antisocial behavior as a product of cerebral disinhibition, caution is urged in overinterpreting causal relationships through neurobehavioral data.
BACKGROUND: The hippocampal formation is damaged early in Alzheimer's disease (AD). An association between temporal lobe volume and cognitive function has been shown in several studies. Increased limbic-hypothalamic-pituitary-adrenal (LHPA) axis function has been suggested to be related to hippocampal atrophy and cognitive impairment. Our hypothesis was that there is a clear link between hippocampal volume -- notably of the CA1 region -- memory (episodic and visuospatial) and decreased feedback sensitivity in the LHPA axis in AD. METHODS: Sixteen medication-free outpatients with mild to moderate AD were included. Hippocampal volume was measured with magnetic resonance imaging. Dexamethasone suppression tests were performed using .5 mg and .25 mg dexamethasone. Three different components in the neuropsychological battery -- Rey 15 item memory test, Alzheimer's Disease Assessment Scale (ADAS) word recall and spatial span from Wechsler Adult Intelligence Scale - Revised neuropsychological instrument (WAIS-R NI) -- were found to represent episodic and visuospatial memory. RESULTS: Low hippocampal CA1 volume and high post-dexamethasone cortisol levels in combination were significantly associated with Rey 15 item memory and spatial span test outcomes. No association was found between LHPA feedback and hippocampal volume. CONCLUSIONS: Low hippocampal volume and a disturbed negative feedback in the LHPA axis link to specific cognitive impairments in Alzheimer's disease.
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The authors performed neuropsychological testing in 21 patients with myotonic dystrophy type 1 (DM1) and 21 with type 2 (DM2) and healthy controls. They detected no general cognitive deficit in either DM1 or DM2, but compared to controls, both groups of patients were inferior in tests of prefrontal functioning. Patient groups did not differ in any measure. Mood status was not related to neuropsychological performance. This is consistent with findings of executive dysfunction in both DM1 and DM2.