Exploring the cognitive load of negative thinking: A novel dual-task experiment

Background and Objectives

Females are more likely to engage in the preoccupation of past negative experiences than males, which might contribute to their greater tendency toward depression. However, there is limited understanding regarding the cognitive basis for the negative autobiographical information processing of females. In the present study, we assessed the cognitive resources required for negative thinking, by using a novel dual-task paradigm that combined think-aloud and time-estimation tasks.

Methods

Fifty-three Japanese undergraduate students were asked to think aloud about personal past or future emotional episodes for a particular duration. In addition, they were asked to estimate the duration of their speech. Their estimates were compared to the actual time taken, and the errors were used as indices of cognitive burden during the speech task.

Results

As compared to males, females exhibited greater judgment errors, particularly when thinking about their past negative experiences. This suggests that females allocate more attentional resources toward thinking about the past.

Limitations

Participants could rehearse the task during the time reproduction phase, and the quality of the rehearsal and their memory capacity might have influenced the accuracy of their duration judgment.

Conclusions

Females tend to allocate more attentional resources than males to thinking about past negative episodes, which in turn might be associated with reduced availability of resources for central cognitive control processes such as inhibition of and switching away from processing of negative autobiographical information.     

The differential yet concurrent contributions of motor,cognitive and affective disturbance to freezing of gait in Parkinson's disease

Objectives

We sought to concurrently examine the specific motor, cognitive and affective contributions to self-reported FOG symptoms.

Patients and methods

Ninety-six patients with Parkinson's disease completed the validated freezing of gait questionnaire and had their motor function scored on section three of the Unified Parkinson's Disease Rating Scale questionnaire. A 5-choice reaction time task was administered in order to measure cognitive processing speed and the Beck Depression Inventory was utilised to assess affective disturbance.

Results

The results showed that after controlling disease duration and dopaminergic medication dose, the triad of motor disability, cognitive processing speed and affective symptoms were all significant independent predictors of scores on the freezing of gait questionnaire.

Conclusions

These findings suggest the need to consider the interplay between distinct motor, cognitive and affective domains in aetiological studies of freezing and the development of future therapies.     

Differential reward processing in subtypes of adult attention deficit hyperactivity disorder

Objectives

Abnormalities in reward processing have been found in adolescents and adults with ADHD using the ‘Monetary Incentive Delay’ (MID) task. However, ADHD groups in previous studies were heterogeneous regarding ADHD subtype, gender and, in part, drug treatment status.This study sought to compare neural activations in the ventral striatum (VS) and prefrontal regions during reward processing in homogenous ADHD subtype groups and healthy adults, using the MID task.

Methods

In total, 24 drug-naïve, right-handed male adults with ADHD (12 subjects with combined type (ADHD-ct) and 12 subjects with predominantly inattentive (ADHD-it) type ADHD), and twelve healthy right-handed male control subjects were included.

Results

Compared to ADHD-ct and healthy subjects, ADHD-it subjects showed a bilateral ventral striatal deficit during reward anticipation. In contrast, ADHD-ct subjects showed orbitofrontal hyporesponsiveness to reward feedback when compared with ADHD-it and healthy subjects.

Conclusions

This is the first fMRI study that delineates dysfunctional and subtype-divergent neural and behavioural reward processing in adults with ADHD.     

Analyse clinique au cours d’une marche simple et avec une double tâche chez une population de sujets âgés ambulatoires consultant en gériatrie

Introduction

Gait and balance often change with age. Few studies are available on gait analysis in the elderly. In our work, we have focused on slow walking and variation in pace. Since first introduced by Lundlin, the dual-task paradigm has been largely used to test for the risk of falls and to better understand the link between mild cognitive decline and variation in gait. To our knowledge, very few clinical data are available on the gait changes observed in the elderly in the dual-task situation. In this study, we compared changes in gait and balance between the simple task and the dual-task situation in a 10-m walk test conducted in community-dwelling old people.

Methods

Eighty-nine subjects attending a geriatric outpatient clinic (age 80.76 ± 2.82 years) were included in our protocol. Gait, balance and posture were systematically evaluated during a simple and dual-task 10-m walk using a specific 11-item clinical scale. Gait speed was noted.

Results

Few differences were found in the dual-task walk, only reduced speed, more stops during the walk and less compliance with instructions. These results were correlated with the Mini Mental Status (MMS) score. Systematic clinical analysis failed to identify any links with age, the MMS, the UPDRS, the Tinetti scale or gait speed except for the variables freezing, increased sustention polygon and ataxia.

Discussion

This kind of study appears to offer an attractive analytical approach but would require a more pertinent choice of variables for cognitive evaluation and a more exhaustive set of MRI criteria. Nonetheless, clinical gait analysis could improve our understanding of the consequences of mild cognitive impairment and aging.     

Cognitive training and selective attention in the aging brain: An electrophysiological study

Objective

Age-related deficits in selective attention are hypothesized to result from decrements in inhibition of task-irrelevant information. Speed of processing (SOP) training is an adaptive cognitive intervention designed to enhance processing speed for attention tasks. The effectiveness of SOP training to improve cognitive and everyday functional performance is well documented. However, underlying mechanisms of these training benefits are unknown.

Methods

Participants completed a visual search task evaluated using event-related potentials (ERPs) before and after 10 weeks of SOP training or no contact. N2pc and P3b components were evaluated to determine SOP training effects on attentional resource allocation and capacity.

Results

Selective attention to a target was enhanced after SOP training compared to no training. N2pc and P3b amplitudes increased after training, reflecting attentional allocation and capacity enhancement, consistent with previous studies demonstrating behavioral improvements in selective attention following SOP training.

Conclusions

Changes in ERPs related to attention allocation and capacity following SOP training support the idea that training leads to cognitive enhancement. Specifically, we provide electrophysiological evidence that SOP training may be successful in counteracting age-related declines in selective attention.

Significance

This study provides important evidence of the underlying mechanisms by which SOP training improves cognitive function in older adults.     

Underlying mechanisms of verbal memory deficits in obsessive-compulsive disorder and major depression--the role of cognitive self-consciousness

Background and Objectives

Previous studies have demonstrated that some individuals suffering from obsessive-compulsive disorder (OCD) are impaired in verbal memory performance. This study was designed to investigate the role of cognitive self-consciousness (CSC) as a putative underlying mechanism of these cognitive deficits.

Methods

Verbal memory performance of 36 participants with OCD, 36 individuals with major depression disorder (MDD) and 36 healthy controls was assessed with the California Verbal Learning Test under three different experimental conditions: (1) single-task condition, (2) while simultaneously focusing on their thoughts (CSC condition), (3) while simultaneously focusing on external stimuli (dual-task condition).

Results

Memory performance in the CSC condition and in the dual-task condition was reduced compared to single-task condition but no interaction effect was found.

Limitations

It remains unclear whether CSC and other concepts with an inward self-referential focus of attention (e.g. rumination) differ in the way they influence cognitive performance.

Conclusions

These results confirm the deteriorating influence of heightened CSC on verbal memory encoding but suggest that the effect is not specific to OCD.     

Reduced parietal activation in cervical dystonia after parietal TMS interleaved with fMRI

Objective

Clinically normal hand movement with altered cerebral activation patterns in cervical dystonia (CD) may imply cerebral adaptation. Since impaired sensorimotor integration appears to play a role in dystonia, left superior parietal cortex modulation with repetitive transcranial magnetic stimulation (TMS) was employed to further challenge adaptation mechanisms reflected by changes in cerebral activation.

Methods

Seven CD patients and ten healthy controls were scanned on a 3T magnetic resonance imaging (MRI) scanner with 1 Hz inhibitory interleaved TMS. They executed and imagined right wrist flexion/extension movements. Each task was preceded by a 10-s period with or without TMS.

Results

The activations of both tasks after TMS in controls showed a similar pattern as found in CD without TMS, i.e. activation increases in bilateral prefrontal and posterior parietal regions during both tasks and decreases in right anterior parietal cortex during imagery (P < 0.001). the activations of both tasks after TMS in CD were weaker but with a similar trend in activation changes. Only in the right angular gyrus, TMS significantly failed to induce an activation increase in CD as was seen in the controls (P < 0.001).

Conclusion

The similarity between TMS effects on the distribution of cerebral activations in controls and the pattern seen in CD may support the concept that CD make use of compensatory circuitry enabling clinically normal hand movement. The fact that a similar but weaker TMS effect occurred in CD could suggest that the capacity of compensation is reduced. Particularly for the right angular gyrus, this reduction was statistically significant.     

Linear and non-linear EEG analysis of adolescents with attention-deficit/hyperactivity disorder during a cognitive task

Objective

We aimed to investigate whether electroencephalograph (EEG) dynamics differ in adolescents with attention-deficit/hyperactivity disorder (ADHD) compared with healthy subjects during the performance of a cognitive task.

Methods

We recorded EEGs from 19 scalp electrodes in 11 adolescent boys with ADHD and 12 age-matched healthy boys while the subjects were at rest and during a continuous performance test (CPT). The approximate entropy (ApEn), a non-linear information-theoretic measure, was calculated to quantify the complexity of the EEGs.

Results

The mean ApEn of the ADHD patients was significantly lower than the healthy subjects over the right frontal regions (Fp2 and F8) during the performance of the cognitive task, but not at rest. The spectral analysis showed significant differences between the two groups in the P3 and T4 regions at rest and the Fp2 and F8 regions during task performance.

Conclusions

The differences in EEG complexity between the two groups suggest that cortical information processing is altered in ADHD adolescents, and thus their levels of cortical activation may be insufficient to meet the cognitive requirements of attention-demanding tasks.

Significance

This study suggests that a non-linear measure such as ApEn is useful for investigating neural dysfunctions in adolescents with ADHD.     

Effect of task-irrelevant high-speed verbal stimulation on a visual/verbal word-discrimination task: An event-related potential study

Objectives

We investigated whether incomprehensible high-speed auditory speech stimulation was processed and interacted with visual-word discrimination processing. We hypothesised that an interaction might indicate the capacity of working memory (WM) to perform the temporal processing of auditory verbal information.

Methods

We recorded P300 for a visual-word discrimination Oddball paradigm in 14 healthy subjects. Auditory speech and reversed speech stimulation were presented at various speeds as task-irrelevant stimuli during the P300 tasks.

Results

The P300 latency was prolonged under forward high-speed speech stimuli (×2.5 and ×3.5) compared with the standard speed and white noise, but there was no effect of reversed speech stimuli on the P300 latency during the word-discrimination paradigm.

Conclusions

We considered that high-speed speech stimulation was processed without conscious comprehension and competed with verbal processing during the visual-word-discrimination task, possibly by interfering with the use of WM.

Significance

The present study shows the capacity of the brain to process high-speed verbal stimulation and the interaction with a visual-verbal task.     

Evaluation of mirrored muscle activity in patients with Complex Regional Pain Syndrome

Objective

Motor dysfunction in Complex Regional Pain Syndrome (CRPS) has been associated with bilateral changes in central motor processing, suggesting abnormal coupling between the affected and unaffected limb. We evaluated the occurrence of involuntary muscle activity in a limb during voluntary movements of the contralateral limb (i.e., mirror activity) in unilaterally affected patients to examine disinhibition of contralateral motor activity in CRPS.

Methods

Mirror activity was examined during unimanual rhythmic flexion–extension movements of the wrist through in-depth analysis of electromyography recordings from the passive arm in 20 CRPS patients and 40 controls.

Results

The number of mirror-epochs was comparable for both arms in both CRPS patients and controls. Mirror-epochs in the affected arm of patients were comparable to those in controls. Mirror-epochs in the unaffected arm were shorter and showed less resemblance (in terms of rhythm and timing) to activity of the homologous muscle in the moving arm compared to mirror-epochs in controls.

Conclusions

No evidence for disinhibition of contralateral motor activity was found during unimanual movement.

Significance

Although motor dysfunction in CRPS has been associated with bilateral changes in cortical motor processing, the present findings argue against disinhibition of interhemispheric projections to homologous muscles in the contralateral limb during unimanual movement.     

Animal category-preferential gamma-band responses in the lower- and higher-order visual areas: Intracranial recording in children

Objective

We determined where and when category-preferential augmentation of gamma activity took place during naming of animal or non-animal pictures.

Methods

We studied 41 patients with focal epilepsy who underwent measurement of naming-related gamma-augmentation at 50–120 Hz during extraoperative electrocorticography. The assigned task consisted of naming of a visually-presented object classified as either ‘animal’ or ‘non-animal’.

Results

Within 80 ms following the onset of picture presentation, regardless of stimulus type, gamma-activity in bilateral occipital regions began to be augmented compared to the resting period. Initially in the occipital poles (at 140 ms and after) and subsequently in the lateral, inferior and medial occipital regions (at 320 ms and after), the degree of gamma-augmentation elicited by ‘animal naming’ became larger (by up to 52%) than that by ‘non-animal naming’. Immediately prior to the overt response, left inferior frontal gamma-augmentation became modestly larger during ‘animal naming’ compared to ‘non-animal naming’.

Conclusions

Animal category-preferential gamma-augmentation sequentially involved the lower- and higher-order visual areas. Relatively larger occipital gamma-augmentation during ‘animal naming’ can be attributed to the more attentive analysis of animal stimuli including the face. Animal-preferential gamma-augmentation in the left inferior frontal region could be attributed to a need for selective semantic retrieval during ‘animal naming’.

Significance

A specific program of cortical processing to distinguish an animal (or face) from other objects might be initiated in the lower-order visual cortex.     

Perceptual and response interference in Alzheimer’s disease and mild cognitive impairment

Objectives

The ability to resolve conflicts is indispensable to the function of daily life and decreases with cognitive decline. We hypothesized that subjects with different levels of cognitive impairment exhibit different conflict resolution performances and may be susceptible to interference effects at different stages.

Methods

Sixteen normal controls (NC), 15 mild cognitive impairment (MCI) and seven Alzheimer’s disease (AD) patients were recruited to perform in a modified Eriksen flanker task.

Results

We observed that the AD and MCI patients exhibited smaller accuracy rate and longer response time compared to NC subjects. Longer N2 and P300 latencies were observed in the AD group. Furthermore, the MCI group showed a longer latency than the NC group in the P300 latency. The magnitude of the perceptual and response interference effects was larger in the AD group than the other groups, and the MCI group significantly differed from the NC group at the perceptual level.

Conclusion

The ability to resolve conflict decreased with impaired cognition and the perceptual and response interference effects may be useful in distinguishing MCI and AD.

Significance

The perceptual or response interference effect may potentially be employed as a useful non-invasive probe for the clinical diagnosis of MCI and AD.     

Cognitive traits in inpatient adolescents with and without prior suicide attempts and non-suicidal self-injury

Objective

Establishing a psychiatric diagnosis and assessing suicidal tendencies is often a challenging task particularly in the early stages of an illness. Cognitive impairments characterize different psychiatric entities, but there is no known specific cognitive deficit profile that could help the clinician in achieving the diagnostic task. This study’s aim was to establish a cognitive profile and test its ability to differentiate psychiatric inpatient subgroups, in terms of suicidal risk and diagnosis. The sample constituted of 76 consecutive admissions to the psychiatric adolescent day-care unit, who were admitted for any diagnosis. Assessment included full psychiatric interview and cognitive evaluation, using the COGNISTAT test.

Results

Of the 76 participants, 58% reported having suicidal ideation and 29% reported a prior attempted suicide. Subjects who had a prior suicide attempt had better orientation and attention scores in the COGNISTAT. Other cognitive domains did not differentiate between groups or diagnoses.

Conclusion

These preliminary results suggest a significant association between specific cognitive characteristics and suicidal behavior in adolescents. Those cognitive characteristics might prove clinically useful in the assessment of suicide risk. Further study is needed to establish this association and generalize the conclusion to different populations.     

Comprehension of metaphors in patients with schizophrenia-spectrum disorders

Background

Metaphors, mainly proverbs and idiomatic expressions of ordinary life are commonly used as a model for concretism. Previous studies have shown impaired metaphor comprehension in patients with schizophrenia-spectrum disorders compared to either psychiatric or non-psychiatric control subject. The aim of this study was to detect possible quantitative differences in figurative processing between patients with schizophrenia-spectrum disorders and healthy controls.

Methods

In order to analyse possible dissociations of different aspects of figurative speech, a range of metaphor tasks was used to distinguish between recognition of familiar metaphors, paraphrasing the meaning of the latter and generating novel metaphors: we used a standard proverb test for conventional metaphors consisting of a multiple-choice and a paraphrasing task, and the Metaphoric Triads Test for the assessment of novel metaphors. We included 40 patients with schizophrenia-spectrum disorders and 43 healthy control subjects.

Results

Our results showed that patients had impaired figurative speech processing regarding novel and conventional metaphors. Associations with cognitive functions were detected. Performance on the paraphrasing task was associated with the severity of negative symptoms.

Conclusion

We conclude that patients with schizophrenia-spectrum disorders do exhibit impairments in the recognition and paraphrasing of conventional and the generation of novel metaphors and that some cognitive domains as well the extent of negative symptoms might be associated with these deficits.     

Which cognitive dual-task walking causes most interference on the Timed Up and Go test in Parkinson’s disease: a controlled study

Background

There is evidence that cognitive load has a negative effect on the gait of patients with Parkinson’s disease (PD). However, it is not clear which type of cognitive activities are more likely to affect dual-task abilities in this patient group.

Aims

To compare the cognitive dual-task abilities in patients with PD and control subjects and to analyze the effect of different cognitive activities on the walking ability of patients with PD.

Methods

The Hoehn and Yahr scale, the Freezing of Gait Questionnaire (FOGQ), Montreal Cognitive Assessment (MoCA), and the Functional Reach Test were used to include and exclude the patients. The Timed Up and Go (TUG) test was applied under single and dual-task conditions.

Results

The completion time of TUG was found to be increased in the PD group compared with the healthy controls under single- and dual-task conditions (p?<?0.05). The completion time of TUG was significantly increased in dual-task conditions with complex attention activity (serial subtractions test) compared with other dual-task conditions in patients with PD (p?<?0.001).

Discussion

The gait performance of both healthy subjects and patients with PD was impaired with cognitive activity during walking, and patients with PD showed more impairment under different cognitive dual tasks. Among the other cognitive tasks, the ‘serial sevens’ test, a measure of complex attention, significantly increased the completion time of TUG.

Conclusions

While assessing the dual-task ability of patients with early-stage PD, tasks that increase the demand for complex attention seem to be more sensitive to showing impaired dual-task ability.

     

Investigating cognitive flexibility as a potential mechanism of mindfulness in Generalized Anxiety Disorder

Background and objectives

Research suggests mindfulness-based treatments may enhance efficacy of CBT for Generalized Anxiety Disorder (GAD). One hypothesized mechanism of mindfulness is cognitive flexibility; however, research findings to date are mixed as to a) whether cognitive inflexibility represents a characteristic of GAD, and b) whether mindfulness impacts cognitive flexibility. It is proposed that limitations in study methodology may partially account for these mixed findings. The present study investigated cognitive flexibility as a potential mechanism of mindfulness in a sample with elevated GAD symptoms using a modified emotional Stroop switching task while attempting to control for limitations of previous research. The purpose of the study was: 1) to explore cognitive inflexibility as a potential characteristic of GAD, and 2) to examine whether a brief mindfulness induction has measurable impact on cognitive flexibility.

Methods

A total of 66 participants (53 with elevated GAD symptoms, and 13 non-anxious) were randomized to a mindful-breathing, music-assisted relaxation, or thought wandering condition prior to completing an emotional Stroop and emotional Stroop switching task.

Results

Results suggest that GAD may be characterized by an inflexible style of responding, and exposure to mindfulness and relaxation result in partial improvements in cognitive flexibility.

Limitations

Limitations of this study include small sample size, brief induction period, and use of an analog sample.

Conclusions

The present findings suggest that mindfulness may be associated with partial improvement in cognitive flexibility.     

Dual-task clinical and functional MRI correlates in Parkinson's disease with postural instability and gait disorders

BackgroundDual-task is a challenge for Parkinson's disease patients with postural instability and gait disorders (PD-PIGD).ObjectiveThis study investigated clinical, cognitive and functional brain correlates of dual-task deficits in PD-PIGD patients using quantitative gait analysis, neuropsychological evaluations and functional MRI (fMRI).MethodsTwenty-three PD-PIGD patients performed a clinical assessment of gait/balance abilities. Single and dual-task Timed-Up-and-Go tests were monitored using an optoelectronic system to study turning velocity. Patients underwent executive-attentive function evaluation and two fMRI tasks: motor-task (foot anti-phase movements), and dual-task (foot anti-phase movements while counting backwards by threes starting from 100). Twenty-three healthy subjects underwent neuropsychological and fMRI assessments.ResultsDual-task in PD-PIGD patients resulted in worse gait performance, particularly during turning. Performing the dual-task relative to the motor-fMRI task, healthy subjects showed widespread increased recruitment of sensorimotor, cognitive and cerebellar areas and reduced activity of inferior frontal and supramarginal gyri, while PD-PIGD patients showed increased recruitment of inferior frontal gyrus and supplementary motor area and reduced activity of primary motor, supramarginal and caudate areas. Dual-task gait alterations in patients correlated with balance and executive deficits and with altered dual-task fMRI brain activity of frontal areas.ConclusionsThis study suggested the correlation between dual-task gait difficulties, postural instability and executive dysfunction in PD-PIGD patients. FMRI results suggest that an optimized recruitment of motor and cognitive networks is associated with a better dual-task performance in PD-PIGD. Future studies should evaluate the effect of specific gait/balance and dual-task trainings to improve gait parameters and optimize brain functional activity during dual-tasks.     

Cognitive reserve modulates attention processes in healthy elderly and amnestic mild cognitive impairment: An event-related potential study

Objectives

The study aimed to investigate and compare the effect of cognitive reserve (CR) on brain activation in healthy controls (HC) and amnestic mild cognitive impairment (aMCI) patients during 0-back and 1-back tasks measured by event-related potential (ERP).

Sequential processing in the equiprobable auditory Go/NoGo task: Children vs. adults

Objective

To compare sequential processing in the unwarned auditory equiprobable Go/NoGo task in children and adults, in the context of a recently developed adult schema.

Methods

Adult and child samples completed an equiprobable auditory Go/NoGo task while EEG was recorded from 19 channels. Go and NoGo ERPs were decomposed using unrestricted Varimax-rotated PCAs for the groups separately, and in combination. The separate adult and child components were compared using the Congruence Coefficient. Brain sources of each assessed component were examined using eLORETA.

Results

Corresponding adult/child components were tentatively identified: two N1 subcomponents (N1-1, PN) and P2, followed by N2, P3 (separate P3a/P3b in children), the classic Slow Wave (SW), and a diffuse Late Positivity (LP). While early and late components showed similarities, the intermediate P2 and N2 differed substantially in their stimulus effects.

Conclusions

Aspects of “Go” vs. “NoGo” categorisation differ between adults and children, but subsequent processing reflected in the different Go/NoGo P3 components, and their sequellae, are similar.

Significance

This is the first detailed examination of child responses in this paradigm. The tested schema appears relatively robust in adults, and the child results may aid our understanding of developmental aspects of cognitive processing in normal and atypical individuals.     

Generalization of cognitive training in an Australian sample of schizophrenia patients

Objective

The present study was undertaken to evaluate the effect of cognitive training in improving trained and untrained cognitive processes in schizophrenia.

Methods

A simple pre- and post experimental study with a three month follow-up was conducted to determine the efficacy of cognitive training in speed of processing and executive functions improving cognition in 22 schizophrenia patients.

Results

Significant improvement was found in those cognitive domains specifically targeted in the training protocol, but also to a limited extent on verbal memory and social cognition. There was also evidence of improvements in symptoms and social functioning. The training effects failed to transfer to community functioning skills however. Except for social cognition, these improvements were maintained at 3 month follow-up.

Conclusion

The study highlights the importance of understanding the mechanisms that contribute to the transfer of skills as well as the maintenance of cognitive changes in individuals with schizophrenia.