Cognitive recovery after severe head injury. 3. WAIS verbal and performance IQs as a function of post-traumatic amnesia duration and time from injury.
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Two studies are reported are reported in which severely head-injured patients were followed up and Verbal (VIQ) and Performance (PIQ) IQs obtained on the Wechsler Adult Intelligence Scale at four intervals after injury. In the first study 51 patients were systematically followed, and results were based upon serial testing. In the second study results were based on the earliest data available from an additional 98 patients who had not been followed so systematically, in order to introduce a control for the effects of practice. Patients in both studies were categorised into four groups of the severity of head injury based upon duration of post-traumatic amnesia (PTA). In both studies, VIQ level was found to be related to PTA duration at three months after injury, while PIQ was related to PTA duration at both three and six months. No such relationships were found at 12 and 30 months after injury. Results are discussed in the context of previous studies relating the outcome of head injury to the duration of PTA. (+info)
A pure case of Gerstmann syndrome with a subangular lesion.
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The four symptoms composing Gerstmann's syndrome were postulated to result from a common cognitive denominator (Grundstorung) by Gerstmann himself. He suggested that it is a disorder of the body schema restricted to the hand and fingers. The existence of a Grundstorung has since been contested. Here we suggest that a common psychoneurological factor does exist, but should be related to transformations of mental images rather than to the body schema. A patient (H.P.) was studied, who presented the four symptoms of Gerstmann's syndrome in the absence of any other neuropsychological disorders. MRI showed a focal ischaemic lesion, situated subcortically in the inferior part of the left angular gyrus and reaching the superior posterior region of T1. The cortical layers were spared and the lesion was seen to extend to the callosal fibres. On the basis of an extensive cognitive investigation, language, praxis, memory and intelligence disorders were excluded. The four remaining symptoms (finger agnosia, agraphia, right-left disorientation and dyscalculia) were investigated thoroughly with the aim of determining any characteristics that they might share. Detailed analyses of the tetrad showed that the impairment was consistently attributable to disorders of a spatial nature. Furthermore, cognitive tests necessitating mental rotation were equally shown to be impaired, confirming the essentially visuospatial origin of the disturbance. In the light of this report, the common cognitive denominator is hypothesized to be an impairment in mental manipulation of images and not in body schema. (+info)
Spatial deficits in ideomotor limb apraxia. A kinematic analysis of aiming movements.
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Ideomotor limb apraxia is a classic neurological disorder manifesting as a breakdown in co-ordinated limb control with spatiotemporal deficits. We employed kinematic analyses of simple aiming movements in left hemisphere-damaged patients with and without limb apraxia and a normal control group to examine preprogramming and response implementation deficits in apraxia. Damage to the frontal and parietal lobes was more common in apraxics, but neither frontal nor parietal damage was associated with different arm movement deficits. Limb apraxia was associated with intact preprogramming but impaired response implementation. The response implementation deficits were characterized by spatial but not temporal deficits, consistent with decoupling of spatial and temporal features of movement in limb apraxia. While the apraxics' accuracy was normal when visual feedback was available, it was impaired when visual feedback of either target location or hand position was unavailable. This finding suggests that ideomotor limb apraxia is associated with disruption of the neural representations for the extrapersonal (spatial location) and intrapersonal (hand position) features of movement. The non-apraxic group's normal kinematic performance demonstrates that the deficits demonstrated in the apraxic group are not simply a reflection of left hemisphere damage per se. (+info)
Improvement in specific aspects of neurocognitive performance in children after renal transplantation.
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BACKGROUND: Chronic renal failure in childhood is considered to affect neurocognitive function adversely, and kidney transplantation may ameliorate the deficits. However, previous studies have suffered from the use of poorly matched control groups, comparison of transplant with uncorrected uremia, lack of standardization of dialysis, and insufficiently sensitive neuropsychological tests. METHODS: We studied nine medically stable children and adolescents age 14.2 +/- 3.5 years with end-stage renal disease prior to and again one year after successful renal transplant. At baseline, the Wechsler Intelligence Scale for Children-III (WISC-III) or the Wechsler Adult Intelligence Scale-Revised (WAIS-R) was performed. Repeatable tests used before and after transplant included the Paced Auditory Serial Addition Test (PASAT) or the Children's Paced Auditory Serial Addition Test (CHIPASAT), the Stroop Color-Word Naming Test, the Buschke Selective Reminding Test, the Meier Visual Discrimination Test, the Grooved Pegboard Test, the WISC-III or the WAIS-R Coding subtests and the Trailmaking Test. Computer-based measures of mental processing speed, reaction time, and discrimination sensitivity included the Cognitive Abilities Test (CAT) and the Connors Continuous Performance Test (CPT). Formal kinetic modeling of dialysis delivery ensured adequate renal replacement therapy. Transplant function was good on stable doses of immunosuppressives, without recent rejections at the time of testing. RESULTS: Within-subject comparison showed statistically significant improvement in mental processing speed by CAT, reaction time and discrimination sensitivity by CPT, and working memory by PASAT/CHIPASAT after renal transplant. Other measures were unchanged. CONCLUSION: Mental processing speed and sustained attention improved in children after renal transplantation in a carefully controlled prospective cross-over study. (+info)
Effect of methylphenidate on attention in children with attention deficit hyperactivity disorder (ADHD): ERP evidence.
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Methylphenidate is the most common treatment for attention deficit hyperactivity disorder (ADHD) and has been shown to improve attention and behaviour. However, the precise nature of methylphenidate on specific aspects of attention at different dose levels remains unclear. We studied methylphenidate effects in ADHD from a neurophysiological perspective, recording event-related potentials (ERPs) during attention task performance in normal controls and children with ADHD under different dose conditions. Twenty children with ADHD and 20 age matched controls were assessed with a continuous performance task requiring subjects to identify repeating alphabetic characters. ERPs and behavioural measures were recorded and analyzed for trials where a correct response was made. The ADHD group was assessed off drug (baseline) and on placebo, low (0.28 mg/kg) and high (0.56 mg/kg) dose levels of methylphenidate. The results showed that the ADHD group at baseline was more impulsive and inattentive than controls and had shorter P2 and N2 latencies and longer P3 latencies. Low dose methylphenidate was associated with reduced impulsivity (fewer false alarms) and decreased P3 latencies, whereas the higher dose level was associated with reduced impulsivity and less inattention (more hits), as well as increased P2 and N2 latencies and decreased P3 latencies. Amplitudes were unaffected and there were no adverse effects of the higher dose for any of the children. These results suggest differential dosage effects and a dissociation between dose levels and aspects of processing. (+info)
Biochemical markers of intelligence: a proton MR spectroscopy study of normal human brain.
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Proton magnetic resonance spectroscopy (1H-MRS) offers a unique non-invasive approach to measurement of N-acetylaspartate (NAA) and choline (Cho), putative markers of neuronal and glial integrity. Previous studies revealed that these neurochemicals predict cognitive impairment in diseased subjects, although little is known about their relationship to cognitive functioning in healthy people. We measured the concentrations of NAA and Cho in the left occipitoparietal white matter of 26 healthy adults and compared them with intellectual performance assessed by the Wechsler Adult Intelligence Scale-3. We found that NAA (b = 0.6, p < 0.01) and Cho (b = -0.42, p < 0.01) were independently associated with the Full-Scale Intelligence Quotient. Together, these metabolites accounted for a large proportion of the variance in intelligence (r2 = 0.45). Possible mechanisms underlying these correlations, such as mitochondrial function and myelin turnover, are discussed. 1H-MRS is a sensitive new tool to assess the neuronal underpinnings of cognitive function non-invasively. (+info)
Word recall correlates with sleep cycles in elderly subjects.
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Morning recall of words presented before sleep was studied in relation to intervening night sleep measures in elderly subjects. Night sleep of 30 elderly subjects aged 61-75 years was recorded. Before sleep, subjects were presented with a list of paired non-related words and cued recall was asked immediately after the morning awakening. Recall positively correlated with average duration of NREM/REM cycles, and with the proportion of time spent in cycles (TCT) over total sleep time (TST). No significant correlations were found with other sleep or wake measures. These results suggest the importance of sleep structure for sleep-related memory processes in elderly adults. (+info)
Memory deficits in patients with schizophrenia: preliminary data from the Wechsler Memory Scale-Third Edition support earlier findings.
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OBJECTIVE: To determine whether memory data presented for a schizophrenia sample in the Technical Manual of the Wechsler Memory Scale-Third Edition support trends identified in a previously published review of studies employing an earlier version of the instrument, the Wechsler Memory Scale-Revised. DESIGN: Archival: reformulation of published data. PATIENTS: Patients with schizophrenia, Alzheimer's disease, Korsakoff's syndrome or traumatic brain injury (TBI) for whom intelligence and memory data were reported in the Technical Manual of the Wechsler Adult Intelligence Scale-Third Edition Wechsler Memory Scale-Third Edition (WAIS-III WMS-III). OUTCOME MEASURES: Mean Full Scale, Verbal, and Performance Intelligence Quotients of the WAIS-III and mean WMS-III Immediate and General Memory Indexes. Single-trial learning and learning slope data were also culled from the WAIS-III WMS-III Technical Manual. RESULTS: Memory indexes for patients with Alzheimer's disease or Korsakoff's syndrome were substantially lower than those for patients with schizophrenia or TBI. In tests of learning processes, patients with schizophrenia had an inferior ability to repeat material presented just once, in comparison with the standardization sample. However, they did relatively better with repeated presentations than patients with Alzheimer's disease or Korsakoff's syndrome. The learning slope for patients with schizophrenia demonstrated an ability to absorb and consolidate increasing amounts of material with repeated exposure that is inconsistent with pronounced memory impairment. CONCLUSIONS: Although patients with schizophrenia exhibit new learning deficiencies, their memory capabilities are not substantially weaker than their general intellectual abilities, and do not approach the memory impairment exhibited by patients with Alzheimer's disease or Korsakoff's syndrome. (+info)