Executive functions in multiple sclerosis: an analysis of temporal ordering, semantic encoding, and planning abilities

Cognitive and behavioral outcome of stereotactic laser amydalohippocampotomy in a pediatric setting

We present neuropsychological and functional outcome data in a teenager undergoing stereotactic laser amygdalohippocampotomy (SLAH) who had drug-resistant mesial temporal lobe epilepsy due to left hippocampal sclerosis. Given strong baseline cognitive performance, there was concern for post-operative declines in language and verbal memory were this patient to undergo open resection. She was evaluated pre- and post-ablation with clinical and experimental neuropsychological measures including semantic memory, category-specific object/face recognition and naming, spatial learning, and socio-emotional processing. The patient became seizure-free following SLAH and experienced significant improvements in school performance and social engagement. She experienced improvement in recognition and naming of multiple object categories, memory functions, and verbal fluency. In contrast, the patient declined significantly in her ability to recognize emotional tone from facial expressions, a socio-emotional process that had been normal prior to surgery. We believe this decline was related to surgical disruption of the limbic system, an area highly involved in emotional processing, and suspect such deficits are an under-assessed and unrecognized risk for all surgeries involving the amygdalohippocampal complex and broader limbic system regions. We hope this positive SLAH outcome will serve as impetus for group level research to establish its safety and efficacy in the pediatric setting.

•

Stereotactic laser ablation can be used successfully in pediatric epilepsy.

•

At risk cognitive abilities did not decline after focal ablation in this teenager.

•

Functional improvement was observed that paralleled gains in seizure status and cognition.

•

Deficits still occurred in select areas related to focal structures ablated.

•

Socio-emotional deficits can result from surgeries restricted to the amygdalohippocampal complex.

Validity of the Verbal Concept Attainment Test in multiple sclerosis

OBJECTIVE

As many as 70% of people with multiple sclerosis (MS) have clinically significant cognitive impairment, and most of these individuals exhibit executive dysfunction. Most research concerning executive dysfunction in MS has focused upon nonverbal measures. The Verbal Concept Attainment Test (VCAT) has demonstrated construct validity as an executive function measure in people infected with HIV and in people with focal brain lesions, but its validity among people with MS is unknown. The current study evaluated the VCAT's criterion, diagnostic, and ecological validity in people with MS.

METHOD

A comprehensive neuropsychological battery was administered to 44 healthy individuals and 97 people with MS. Based on existing norms, they were classified as impaired or unimpaired, resulting in 65 people with MS categorized as unimpaired and 32 as impaired. They were administered a battery assessing neuropsychological impairment and disability status.

RESULTS

The VCAT correlated with most measures of neuropsychological function, but its largest correlations occurred with measures of executive function, working memory, and verbal memory. Regarding classification accuracy, the VCAT achieved satisfactory sensitivity and specificity in identifying neuropsychological impairment in people with MS. The VCAT achieved moderate correlations with measures of disability status.

CONCLUSIONS

The data provide evidence for an optimal VCAT cutoff score for establishing neuropsychological impairment in people with MS, and they demonstrate that the VCAT possesses acceptable criterion, diagnostic, and ecological validity. As such, these data support the inclusion of the VCAT in research and clinical practice involving people with MS.

An initial investigation of the reliability and validity of the Compensatory Cognitive Strategies Scale

Although many cognitive performance tests and self-reported cognitive concerns scales have been used to evaluate cognitive functioning, fewer measures assess the use of compensatory cognitive strategies for daily activities among those experiencing mild levels of cognitive impairment. The Compensatory Cognitive Strategies Scale was developed to measure frequency of self-reported cognitive strategies to decrease distractions, organise and sequence activities, and to utilise newly available computer aids to assist memory among those with multiple sclerosis (MS). Cronbach's alpha, a measure of internal consistency reliability, was .89 and .90 in two different samples. Concurrent validity was supported by the total score's moderate correlation with the MMQ-Strategy Scale (r_s = .67) and by a statistically significant increase in total scores for those who had participated in an intervention designed to improve their cognitive abilities. Correlations were stronger with another strategy measure than with measures of other constructs such as health-promoting behaviours, thus supporting the scales convergent versus divergent validity. These initial findings suggest that the Compensatory Cognitive Strategies Scale may be useful to both researchers and clinicians working to build compensatory strategies for day-to-day functioning among those with mild cognitive impairment.

Verbal Learning Processes in Patients with Glioma of the Left and Right Temporal Lobes

Recent research supports the utility of process variables in understanding mechanisms underlying memory impairments. The Hopkins Verbal Learning Test-Revised (HVLT-R) was administered to 84 patients with left (LTL, n = 58) or right temporal lobe glioma (RTL, n = 26) prior to surgical resection. Primary HVLT-R measures of learning and memory and numerous learning process indices were computed. Both groups exhibited frequent memory impairment (>30%), with greater severity in the LTL group. Patients with LTL glioma also exhibited lower semantic clustering scores than RTL patients, which were highly associated with Total Recall (ρ = 0.83) and Delayed Recall (ρ = 0.68). Learning slope and a novel measure of learning efficiency were also significantly associated with primary memory measures, though scores were similar across the LTL and RTL groups. While lesions to either temporal lobe impact verbal memory, semantic encoding appears to depend upon the integrity of LTL structures in particular.

Information processing and magnetic resonance imaging indices of brain pathology in multiple sclerosis

Accumulation of central nervous system (CNS) pathology affects cognitive processing speed and efficiency and is thought to underlie attentional and executive deficits in multiple sclerosis (MS). Most clinical neuropsychological tests are multifactorial and are limited in their sensitivity to specific cognitive processes. This may, in part, account for the low to moderate correlations between clinical test results and magnetic resonance imaging (MRI) indices of brain pathology. We compared the ability of a clinical and an experimental test of cognitive processing speed to differentiate domain-specific cognitive changes in MS, and examined relations between test performance and MRI measures of brain pathology. Twelve MS patients and 12 controls completed the Paced Auditory Serial Addition Test (PASAT) and the Attention Networks Test-Interactions (ANT-I), a computerized response latency task. Subjects also had MRI scans that included T1, T2, and fluid-attenuated inversion recovery (FLAIR) sequences that provided global and localized volumetric measures. Patients made more errors on the PASAT and were slower on the ANT-I. The ANT-I also revealed specific deficits in response inhibition. In addition, ANT-I performance was associated with changes in a number of MRI measures, which was not the case for the PASAT. Reaction time paradigms that manipulate within-task demands on distinct cognitive functions may provide meaningful markers of brain disease burden in MS.

Deconstructing spatial working memory and attention deficits in multiple sclerosis

OBJECTIVE

To investigate whether spatial working memory (WM) is impaired in multiple sclerosis (MS), and, if it is, to localize impairment to specific cognitive subprocess(es).

METHOD

In Experiment 1, MS and control participants performed computerized memory-span and visuomotor tasks. WM subprocesses were taxed by manipulating (1) the requirement to remember serial order, (2) delay duration, and (3) the presence of irrelevant stimuli during target presentation. In Experiment 2, recall and recognition tests varied the difficulty of WM retrieval. In Experiment 3, an attention-cueing task tested the ability to voluntarily and rapidly reorient attention.

RESULTS

Performance was worse for MS than for control participants in both spatial recall (Exp. 1 span: 95% CIMS = [5.11, 5.57], 95% CIControls = [5.58, 6.03], p = .003, 1-tailed; Exp. 2 span: 95% CIMS = [4.44, 5.54], 95% CIControls = [5.47, 6.57], p = .006, 1-tailed) and recognition (accuracy: 95% CIMS = [0.71, 0.81], 95% CIControls = [0.79, 0.88], p = .01, 1-tailed) tests. However, there was no evidence for deficits in spatiotemporal binding, maintenance, retrieval, distractor suppression, or visuomotor processing. In contrast, MS participants were abnormally slow to reorient attention (cueing effect (ms): 95% CIMS: [90, 169], 95% CIControls: [29, 107], p = .015, 1-tailed).

CONCLUSIONS

Results suggest that, whereas spatial WM is impaired in MS, once spatial information has been adequately encoded into WM, individuals with MS are, on average, able to maintain and retrieve this information. Impoverished encoding of spatial information, however, may be due to inefficient voluntary orienting of attention.

Altered functional adaptation to attention and working memory tasks with increasing complexity in relapsing-remitting multiple sclerosis patients

As attention, processing speed, and working memory seem to be fundamental for a broad range of cognitive performance, the present study on patients with mild forms of relapsing-remitting multiple sclerosis (RR-MS) focused on these domains. To explore subtle neuropsychological changes in either the clinical or fMRI domain, we applied a multistep experimental design with increasing task complexity to investigate global brain activity, functional adaptation, and behavioral responses to typical cognitive processes related to attention and working memory. Fifteen patients with RR-MS (mean age 38 years, 22-49 years, 9 females, mean disease duration 5.9 years (SD = 3.6 years), mean Expanded Disability Status Scale score, 2.3 (SD = 1.3) but without reported cognitive impairment), and 15 age-matched healthy controls (HC; mean age, 34 years, 23-50 years, 6 women) participated. After a comprehensive neuropsychological assessment, participants performed different fMRI experiments testing attention and working memory. In the neuropsychological assessment, patients showed only subtle reduction in learning and memory abilities. In the fMRI experiments, both groups activated the brain areas typically involved in attention and working memory. HC showed a linear in- or decrease in activation paralleling the changing task complexity. Patients showed stronger activation change at the level of the simple tasks and a subsequent saturation effect of (de-)activation at the highest task load. These group/task interaction differences were found in the right parahippocampal cortex and in the middle and medial frontal regions. Our results indicate that, in MS, functional adaptation patterns can be found which precede clinical evidence of apparent cognitive decline.

Verbal memory impairment in severe closed head injury: the role of encoding and consolidation

We applied the item-specific deficit approach (ISDA) to California Verbal Learning Test data obtained from 56 severe, acceleration-deceleration closed head injury (CHI) participants and 62 controls. The CHI group demonstrated deficits on all ISDA indices in comparison to controls. Regression analyses indicated that encoding deficits, followed by consolidation deficits, accounted for most of the variance in delayed recall. Additionally, level of acquisition played a partial role in CHI-associated consolidation difficulties. Finally, CHI encoding deficits were largely driven by low semantic clustering during list learning. These results suggest that encoding (primary) and consolidation (secondary) deficits account for CHI-associated verbal memory impairment.

Neuropsychological impairment in systemic lupus erythematosus: a comparison with multiple sclerosis

In this manuscript, we review literature describing the neuropsychological and brain imaging characteristics of systemic lupus erythematosus (SLE) patients. The findings are compared and contrasted with multiple sclerosis (MS) studies, revealing similarities and differences of interest to clinicians and researchers. While cognitive impairment is somewhat less common in SLE than MS, the diseases share a similar cognitive profile with deficits most prominent on tests emphasizing the speed of information processing, working memory, and visual/spatial learning, and memory. In early or more mildly affected patients, diffuse white matter damage, which may not be apparent on conventional brain imaging, plays a major role in clinical presentation and cognitive testing. The causes of white matter damage are very different, however, and in later stages of the disease MS and SLE appear to give rise to different forms of cerebral pathology. MS may be characterized by increasing brain atrophy affecting especially the cortical and deep gray matter, at least after conversion to secondary progressive course. There is less evidence for neurodegenerative changes in SLE, but patients are increasingly at risk for cerebrovascular disease. We conclude by offering some suggestions for future clinical and imaging research.

Cognitive impairment in multiple sclerosis

Cognitive dysfunctions are frequent symptoms of multiple sclerosis (MS) and occur in up to 65% of patients. Especially memory, attention, executive and visual constructive functions are impaired. These problems strongly affect patients' ability to work, social relationships, and quality of life. Symptoms of physical disabilities can arise independently. Cognitive dysfunctions are clear indicators of MS progression, because they represent highly complex functions that depend on the integrity of the neuronal networks. Once manifested after a relapse, they remain stable . Given a differentiating diagnosis, it is possible to treat these dysfunctions by cognitive training and with pharmaceutical drugs, for example by immunomodulating drugs. However, treatment options are limited at present. This report provides a detailed description of cognitive functions and performance in MS patients, their comorbidities such as fatigue and depression and therapeutic options.