Novel n-back spatial working memory task using eye movement response

Working Memory Phenotypes in Early Multiple Sclerosis: Appraisal of Phenotype Frequency, Progression and Test Sensitivity

Working memory (WM) impairments are common and debilitating symptoms of multiple sclerosis (MS), often emerging early in the disease. Predominantly, WM impairments are considered in a binary manner, with patients considered either impaired or not based on a single test. However, WM is comprised of different activated subcomponents depending upon the type of information (auditory, visual) and integration requirements. As such, unique WM impairment phenotypes occur. We aimed to determine the most frequent WM phenotypes in early MS, how they progress and which WM test(s) provide the best measure of WM impairment. A total of 88 participants (63 early relapsing–remitting MS: RRMS, 25 healthy controls) completed five WM tests (visual–spatial, auditory, episodic, executive) as well as the symbol digit modalities test as a measure of processing speed. RRMS patients were followed-up for two years. Factors affecting WM (age/gender/intelligence/mood) and MS factors (disease duration/disability) were also evaluated. Some 61.9% of RRMS patients were impaired on at least one WM subcomponent. The most subcomponents impaired were visual,–spatial and auditory WM. The most common WM phenotypes were; (1) visual–spatial sketchpad + episodic buffer + phonological loop + central executive, (2) visual–spatial sketchpad + central executive. The test of visual–spatial WM provided the best diagnostic accuracy for detecting WM impairment and progression. The SDMT did not achieve diagnostic accuracy greater than chance. Although this may be unsurprising, given that the SDMT is a measure of cognitive processing speed in MS, this does highlight the limitation of the SDMT as a general screening tool for cognitive impairment in early MS.

Effects of an Eye-Tracking Linkage Attention Training System on Cognitive Function Compared to Conventional Computerized Cognitive Training System in Patients with Stroke

Objective: The purpose of the study was to investigate the effects of an eye-tracking linkage attention training system on cognitive function compared to a conventional computerized cognitive training system in stroke patients with cognitive impairment. Methods: This retrospective study was enrolled 40 stroke patients who received cognitive rehabilitation. The intervention consisted of 30 sessions and 30 min per session. Before and after the intervention, we assessed cognitive functions by Mini-Mental State Examination (MMSE-K) and activities of daily living by Modified Barthel Index (K-MBI) and administered a computerized neuropsychological test (CNT). Results: In both groups, there were significant improvements in MMSE-K and K-MBI (p < 0.05). In the visual and auditory attention test of the CNT, the eye-tracking linkage attention training group was significantly improved after intervention (p < 0.05). However, there were no significant differences in the conventional computerized cognitive training group. In addition, there were significant improvements in all memory tests of the CNT in the eye-tracking linkage attention training group. However, in the conventional computerized cognitive training group, there were significant improvements in some memory tests of the CNT. Conclusions: The training of poststroke cognitive impairment patients using an eye-tracking linkage attention training system may improve visuospatial attention and may be helpful for the improvement of short-term memory and independent performances in daily life activities.

Cinnamon users with prediabetes have a better fasting working memory: a cross-sectional function study

Working memory (WM) is impaired in prediabetes. We hypothesized that culinary herbs and spices may decrease insulin resistance (IR) and improve WM in prediabetes. Healthy people aged ≥60 years with prediabetes (fasting blood glucose 100-125 mg/dL) (47 men and 46 women) whose food and culinary herb intakes were established with a food frequency questionnaire had body composition assessed and fasting glucose and insulin measured. Working memory and Mini-Mental State Examination (MMSE) were assessed on the same occasion. The contributions to associations between WM and diet, body fat, and IR were estimated by linear regression. Compared with nonusers, cinnamon users had significantly less frequent physical activity (2.9 vs. 4.4 times per week) and more often used fresh ginger (93.3% vs. 64.1%) and ginger in cooking (60.0% vs. 32.1%). Cinnamon users also had a better WM (2.9 vs. 2.5, P < .001). Cinnamon had a significant effect (users were 0.446 higher), but not ginger or curry usage, in predicting WM. For sociodemographic variables, only education (years) was significant in predicting WM (β = 0.065). Other significant determinants of WM were total fat mass (kilograms) (β = -0.024) and MMSE (β = 0.075). After adjustment for age and sex, cinnamon use, education, and MMSE remained significant individual predictors. In the final model, in which all variables listed were adjusted simultaneously, cinnamon users still had a significantly higher WM than nonusers. Cinnamon usage is associated with a better WM, not accounted for by dietary quality or IR, in untreated prediabetes.

Ocular motor measures of cognitive dysfunction in multiple sclerosis II: working memory

Our companion paper documents pervasive inhibitory deficits in multiple sclerosis (MS) using ocular motor (OM) measures. Here we investigated the utility of an OM working memory (WMem) task in characterising WMem deficits in these patients as a function of disease status and disease duration. 22 patients with CIS, 22 early clinically definite MS patients (CDMS: <7 years of diagnosis), 22 late CDMS patients (>7 years from diagnosis), and 22 healthy controls participated. All participants completed the ocular motor WMem task, the paced auditory serial addition test (PASAT), and the symbol digit modalities test (SDMT). Clinical disability was characterised in CDMS patients using the Expanded Disability Severity Scale (EDSS). WMem performance was measured as proportion of errors (WMem errors), saccade latency, and relative sensitivity to WMem loading (WMem effect), an indicator of WMem capacity. All patient groups performed more WMem errors than controls with proportion of WMem errors, and degree of WMem effect increasing with increasing disease duration. A larger WMem effect, reflecting poorer WMem capacity, corresponded to poorer performance on neuropsychological measures, and a higher disability score for CDMS patients with the longest disease duration; an observation that suggests wider implication of WMem executive processes with advancing disease. Conspicuously, performance decrements on standard neuropsychological testing did not similarly increase commensurate with disease duration. The ocular motor WMem task appears to meaningfully dissociate WMem deficit from healthy individuals as well as a function of increasing disease duration. Potentially, this task represents a highly informative and objective method by which to ascertain progressive WMem changes from the earliest inception of MS.

Oculomotor executive function abnormalities with increased tic severity in Tourette syndrome

BACKGROUND

Reports conflict as to whether Tourette syndrome (TS) confers deficits in executive function. This study's aim was to evaluate executive function in youths with TS using oculomotor tasks while controlling for confounds of tic severity, age, medication, and severity of comorbid disorders.

METHOD

Four saccade tasks requiring the executive functions of response generation, response inhibition, and working memory (prosaccade, antisaccade, 0-back, and 1-back) were administered. Twenty youths with TS and low tic severity (TS-low), nineteen with TS and moderate tic severity (TS-moderate), and 29 typically developing control subjects (Controls) completed the oculomotor tasks.

RESULTS

There were small differences across groups in the prosaccade task. Controlling for any small sensorimotor differences, TS-moderate subjects had significantly higher error rates than Controls and TS-low subjects in the 0-back and 1-back tasks. In the 1-back task, these patients also took longer to respond than Controls or TS-low subjects.

CONCLUSIONS

In a highly controlled design, the findings demonstrate for the first time that increased tic severity in TS is associated with impaired response inhibition and impaired working memory and that these executive function deficits cannot be accounted for by differences in age, medication or comorbid symptom severity.

Delineation of the working memory profile in female FMR1 premutation carriers: the effect of cognitive load on ocular motor responses

Fragile X mental retardation 1 (FMR1) premutation carriers (PM-carriers) are characterised as having mid-sized expansions of between 55 and 200 CGG repeats in the 5' untranslated region of the FMR1 gene. While there is evidence of executive dysfunction in PM-carriers, few studies have explicitly explored working memory capabilities in female PM-carriers. 14 female PM-carriers and 13 age- and IQ-matched healthy controls completed an ocular motor n-back working memory paradigm. This task examined working memory ability and the effect of measured increases in cognitive load. Female PM-carriers were found to have attenuated working memory capabilities. Increasing the cognitive load did not elicit the expected reciprocal increase in the task errors for female PM-carriers, as it did in controls. However female PM-carriers took longer to respond than controls, regardless of the cognitive load. Further, FMR1 mRNA levels were found to significantly predict PM-carrier response time. Although preliminary, these findings provide further evidence of executive dysfunction, specifically disruption to working memory processes, which were found to be associated with increases in FMR1 mRNA expression in female PM-carriers. With future validation, ocular motor paradigms such as the n-back paradigm will be critical to the development of behavioural biomarkers for identification of PM-carrier cognitive-affective phenotypes.