Normative neuropsychological test performance: effects of age, education, gender and ethnicity

Material-specific memory changes after anterior temporal lobectomy as predicted by the intracarotid amobarbital test

PURPOSE

The intracarotid amobarbital test (IAT) has been shown to predict verbal memory changes after anterior temporal lobectomy (ATL). Seeking to extend these findings, we examined two questions: (a) What is the relationship between material-specific aspects of IAT memory and material-specific memory changes after ATL? and (b) Which IAT memory score(s) optimally predict memory changes after surgery, the memory score after injection ipsilateral to the seizure focus, the memory score after injection contralateral to the seizure focus, or the IAT asymmetry score, comprising the ipsilateral minus contralateral injection scores?

METHODS

Seventy left hemisphere language-dominant patients undergoing ATL for treatment of medically refractory seizures were administered a verbal and visuospatial recognition memory test before surgery and 3 weeks after surgery. IAT memory recognition scores for words and designs were used to predict verbal and visuospatial memory changes after surgery.

RESULTS

After surgery, left ATL patients declined in verbal memory, whereas right ATL patients declined in visuospatial memory. IAT total recognition memory scores (collapsed across all types of materials) and IAT word memory scores were associated with postoperative verbal memory decline. This relationship was significant for the IAT ipsilateral injection memory scores and the IAT hemispheric asymmetry scores. IAT memory performances were not related to visuospatial memory changes.

CONCLUSIONS

Results indicate IAT memory measures to be related to postoperative verbal, but not visuospatial, memory change. A specific relationship was found between postoperative verbal memory change and IAT verbal memory after injection ipsilateral to the seizure focus, when relying primarily on the contralateral hemisphere. This finding is consistent with the functional reserve model of memory change in ATL.

Continuous performance tests are sensitive to ADHD in adults but lack specificity. A review and critique for differential diagnosis

Historically, the focus for Attention Deficit Hyperactivity Disorder (ADHD) has been on children, with considerable research and many opinions available in this area. More recently, the focus has been expanded to include ADHD in adults. Assessment of ADHD in adults is complicated by the high rate of co-occurring disorders as well as symptom overlap with a number of disorders. One popular family of measures for the assessment of attention and executive control is the continuous performance test (CPT). A review of the available research on CPTs reveals that they are quite sensitive to CNS dysfunction. This is both a strength and a limitation of CPTs in that multiple disorders can result in impaired performance on a CPT. The high sensitivity of CPTs is further complicated by the multiple variations of CPTs available, some of which may be more sensitive or demonstrate better specificity to ADHD in adults than others. If CPTs are to be used clinically, further research will be needed to answer the questions raised by this review.

An fMRI study of sex differences in regional activation to a verbal and a spatial task

Sex differences in cognitive performance have been documented, women performing better on some phonological tasks and men on spatial tasks. An earlier fMRI study suggested sex differences in distributed brain activation during phonological processing, with bilateral activation seen in women while men showed primarily left-lateralized activation. This blood oxygen level-dependent fMRI study examined sex differences (14 men, 13 women) in activation for a spatial task (judgment of line orientation) compared to a verbal-reasoning task (analogies) that does not typically show sex differences. Task difficulty was manipulated. Hypothesized ROI-based analysis documented the expected left-lateralized changes for the verbal task in the inferior parietal and planum temporal regions in both men and women, but only men showed right-lateralized increase for the spatial task in these regions. Image-based analysis revealed a distributed network of cortical regions activated by the tasks, which consisted of the lateral frontal, medial frontal, mid-temporal, occipitoparietal, and occipital regions. The activation was more left lateralized for the verbal and more right for the spatial tasks, but men also showed some left activation for the spatial task, which was not seen in women. Increased task difficulty produced more distributed activation for the verbal and more circumscribed activation for the spatial task. The results suggest that failure to activate the appropriate hemisphere in regions directly involved in task performance may explain certain sex differences in performance. They also extend, for a spatial task, the principle that bilateral activation in a distributed cognitive system underlies sex differences in performance.

Sex differences in brain gray and white matter in healthy young adults: correlations with cognitive performance

Sex-related differences in behavior are extensive, but their neuroanatomic substrate is unclear. Indirect perfusion data have suggested a higher percentage of gray matter (GM) in left hemisphere cortex and in women, but differences in volumes of the major cranial compartments have not been examined for the entire brain in association with cognitive performance. We used volumetric segmentation of dual echo (proton density and T2-weighted) magnetic resonance imaging (MRI) scans in healthy volunteers (40 men, 40 women) age 18-45. Supertentorial volume was segmented into GM, white matter (WM), and CSF. We confirmed that women have a higher percentage of GM, whereas men have a higher percentage of WM and of CSF. These differences sustained a correction for total intracranial volume. In men the slope of the relation between cranial volume and GM paralleled that for WM, whereas in women the increase in WM as a function of cranial volume was at a lower rate. In men the percentage of GM was higher in the left hemisphere, the percentage of WM was symmetric, and the percentage of CSF was higher in the right. Women showed no asymmetries. Both GM and WM volumes correlated moderately with global, verbal, and spatial performance across groups. However, the regression of cognitive performance and WM volume was significantly steeper in women. Because GM consists of the somatodendritic tissue of neurons whereas WM comprises myelinated connecting axons, the higher percentage of GM makes more tissue available for computation relative to transfer across distant regions. This could compensate for smaller intracranial space in women. Sex difference in the percentage and asymmetry of the principal cranial tissue volumes may contribute to differences in cognitive functioning.

Differences in Neuropsychological Functioning Associated With Age, Education, Neurological Status, and Magnetic Resonance Imaging Findings In Neurologically Healthy Elderly Individuals

In a cross-sectional study, a sample of 113 individuals, 55 to 85 years old, without any neurological diseases was investigated. The study provides information on differences associated with age, education, and gender, and in relation to neurological status, magnetic resonance imaging, and cognitive functioning. Differences between age groups were shown in memory, constructional, and language functions, and especially in tests related to speed and attention. Education was related to most of the cognitive functions, but especially to verbal intellectual functions, visual and logical memory, language functions, and calculation. Gender differences were found in finger tapping, constructional functions, and verbal intellectual functions. Primitive reflexes showed a tendency to correlate with comprehension and memory of sentences. Extrapyramidal signs were related to psychomotor speed, and attention, verbal fluency, and set shifting together with intellectual functions and learning. Central atrophy on magnetic resonance imaging was related to memory functions in those 65 and 70 years of age, whereas in the oldest age groups immediate recall was associated with the severity of lesions.

A Note of Caution: Normative Neuropsychological Test Performance: Effects of Age, Education, Gender and Ethnicity: A Comment on Saykin et al. (1995)

Recently Saykin et at. (1995), departing from their results in a sample of normal individuals, concluded that, "Demographic factors infrequently account for more than 10% of the variance for many neuropsychological teat scores" (p. 79). In this short article it is pointed out that their results have to be interpreted with extreme caution, because the education and age ranges they used are not valid to analyze the education and age effects on neuropsychological test performance. Educational effect does not represent a linear effect; rather, it represents a kind of negatively accelerated curve, and age effect becomes evident only in a population older than the sample they have selected.

Neurocognitive and psychosocial correlates of ventroposterolateral pallidotomy surgery in Parkinson's disease

The purpose of this study was to characterize the neuropsychological and psychosocial profile of patients with Parkinson's disease before and after they underwent unilateral left or right pallidotomy, to assess specific cognitive and personality changes caused by lesioning the globus pallidus, and to predict favorable surgical outcome based on these measures. Eighteen patients underwent comprehensive neuropsychological assessment before and after left-sided pallidotomy (10 patients) or right-sided pallidotomy (eight patients). The findings support the presence of frontosubcortical cognitive dysfunction in all patients at baseline and a specific pattern of cognitive impairment following surgery, with side of lesion being an important predictor of pattern and degree of decline. Specifically, patients who underwent left-sided pallidotomy experienced a mild decline on measures of verbal learning and memory, phonemic and semantic verbal fluency, and cognitive flexibility. Patients who underwent right-sided pallidotomy exhibited a similar decline in verbal learning and cognitive flexibility, as well as a decline in visuospatial construction abilities; however, this group also exhibited enhanced performance on a delayed facial memory measure. Lesioning the globus pallidus may interfere with larger cognitive circuits needed for processing executive information with disruption of the dominant hemisphere circuit, resulting in greater deficits in verbal information processing. The left-sided pallidotomy group also reported fewer symptoms of depression and anxiety following surgery. This enhanced mood functioning was not seen for the right-sided pallidotomy group. No relationships were noted between cognitive impairment or advanced age at baseline and surgical outcome. This study provides objective evidence for specific changes in neurocognitive and psychosocial functioning following left- and right-sided pallidotomy.