Working memory training in patients with chronic schizophrenia: a pilot study

Rehabilitation of working memory after acquired brain injury and multiple sclerosis: A systematic review

The objective is to study the effectiveness of working memory (WM) rehabilitation after Acquired brain injury (ABI) and multiple sclerosis (MS). A systematic database search of published studies, following PRISMA recommendations, with assessment of methodological quality and risk of bias, was conducted. The results were analysed according to the rehabilitation method used. 31 studies (including 14 class I) were included, and 11 different training programs were identified. Despite great variability in training methodology and outcome measures, the results were positive overall. However, only three rehabilitation programs showed a transfer effect to WM (near) and daily life with long-term maintenance. The results were more variable for protocols limited to the use of computerized n-back training tasks. Overall, the current evidence supports multi-task WM training rather than single-task-limited program. It also supports early and long duration training, with some therapist support. However, it is not possible, to date, to make strong recommendations regarding the rehabilitation program to be used preferentially. Although results are encouraging, level of evidence remains modest, particularly regarding the maintenance of the therapeutic effect after the end of training, and the transfer to everyday life skills. The influence of rehabilitation parameters (training duration, therapist involvement … ) remains difficult to assess.

Non-pharmacological randomized intervention trial for the management of neuropsychological symptoms in outpatients with progressive multiple sclerosis

PURPOSE

Despite typically more pronounced cognitive and mental health issues in progressive disease courses of multiple sclerosis (PMS), rehabilitation research in this subgroup is rare. The efficacy of two non-pharmacological interventions with positive results from prior investigations was therefore examined in PMS specifically.

METHODS

Persons with PMS (pwPMS) received either computerized cognitive training (BrainStim), standardized cognitive-behavioral group sessions (Metacognitive Training [MaTiMS]), or a combination of both in an ambulatory setting. Neuropsychological assessment was conducted before and after the four-week intervention.

RESULTS

37 participants (13 with primary/24 with secondary PMS, meanage = 52.87, SDage = 7.11, meanEDSS = 4.02, SDEDSS = 1.35) entered analyses. The BrainStim group improved in immediate and delayed verbal memory, recognition, verbal working memory, and perceived cognitive deficits while experiencing increased anxiety post-intervention. MaTiMS participants reported high program satisfaction and less cognitive difficulties at retest. The Combination group performed better in immediate and delayed verbal memory, and in information processing speed after training. Descriptive data further indicated positive effects on anxiety and depression in the MaTiMS and Combination group.

CONCLUSIONS

While objective cognitive performance improved when explicitly trained, psychoeducative sessions contributed to subjective mental health. The combination of both approaches is thus suggested, considering the specific needs of pwPMS treated in an ambulatory setting.

Working memory and sensory memory in subclinical high schizotypy: An avenue for understanding schizophrenia?

The search for robust, reliable biomarkers of schizophrenia remains a high priority in psychiatry. Biomarkers are valuable because they can reveal the underlying mechanisms of symptoms and monitor treatment progress and may predict future risk of developing schizophrenia. Despite the existence of various promising biomarkers that relate to symptoms across the schizophrenia spectrum, and despite published recommendations encouraging multivariate metrics, they are rarely investigated simultaneously within the same individuals. In those with schizophrenia, the magnitude of purported biomarkers is complicated by comorbid diagnoses, medications and other treatments. Here, we argue three points. First, we reiterate the importance of assessing multiple biomarkers simultaneously. Second, we argue that investigating biomarkers in those with schizophrenia-related traits (schizotypy) in the general population can accelerate progress in understanding the mechanisms of schizophrenia. We focus on biomarkers of sensory and working memory in schizophrenia and their smaller effects in individuals with nonclinical schizotypy. Third, we note irregularities across research domains leading to the current situation in which there is a preponderance of data on auditory sensory memory and visual working memory, but markedly less in visual (iconic) memory and auditory working memory, particularly when focusing on schizotypy where data are either scarce or inconsistent. Together, this review highlights opportunities for researchers without access to clinical populations to address gaps in knowledge. We conclude by highlighting the theory that early sensory memory deficits contribute negatively to working memory and vice versa. This presents a mechanistic perspective where biomarkers may interact with one another and impact schizophrenia-related symptoms.

Obstetric complications and cognition in schizophrenia: a systematic review and meta-analysis

BACKGROUND

Schizophrenia (SZ) is a complex brain disorder linked to cognitive and neurostructural abnormalities that involves genetic and environmental factors with obstetric complications (OCs) at birth conferring a high risk for the disease. Indeed, current research in the general population describes the deleterious effect of OCs on cognitive performance in adulthood. With this rationale, we aim to review the relationship between OCs and cognition in SZ and related psychotic disorders.

METHODS

A systematic review and meta-analysis describing cognitive function and OCs in patients with SZ and related disorders were conducted. PubMed, EmBase, SCOPUS, and the Cochrane Library were systematically searched to identify eligible studies up to January 2022. We calculated the effect sizes (Hedges' g) of cognitive domains within each study and quantified the proportion of between-study variability using the I² statistic. Homogeneity was assessed using the Q-statistic (X²). The study was registered on PROSPERO (CRD42018094238).

RESULTS

A total of 4124 studies were retrieved, with 10 studies meeting inclusion criteria for the systematic review and eight for meta-analysis. SZ subjects with OCs showed poor verbal memory [Hedges' g = -0.89 (95% CI -1.41 to -0.37), p < 0.001] and working memory performance [Hedges' g = -1.47 (95% CI -2.89 to -0.06), p = 0.01] in a random-effect model compared to those without OCs.

CONCLUSIONS

OCs appear to have a moderate impact on specific cognitive such as working memory and verbal memory. Our findings suggest that OCs are associated with brain development and might underlie the cognitive abnormalities described at onset of psychosis.

Advances in Cognitive Remediation Training in Schizophrenia: A Review

Cognitive Remediation Training (CRT) in schizophrenia has made great strides since its introduction in the 1990s. CRT was developed with the aim of improving the everyday functioning of individuals living with cognitive impairment. MEDLINE, PsychINFO, and Google Scholar were searched to extract peer-reviewed randomized controlled trials to produce the current review article. The aim of the present review is to summarize CRT effects on addressing cognitive changes in patients undergoing CRT as defined by the Cognitive Remediation Experts Workshop and to describe the areas of greatest impact in specific cognitive domains. Another area of this review aims to summarize the modalities of intervention (paper and pencil; computerized; home bound), the persistence of improvements, and their generalization to other domains of functioning. Finally, this review delineates barriers for wider dissemination of CRT, such as the transfer of research findings into clinical everyday practice and future developments of CRT.

A randomized controlled trial of working memory and processing speed training in schizophrenia

BACKGROUND

Although prior research has shown that cognitive training may improve cognition for schizophrenia patients, it is currently unclear which domains of cognition should be targeted in training. One suggestion is to target low- or mid-level cognitive processes. In particular, working memory (WM) and processing speed (PS) have been named as two key areas of impairment in schizophrenia, and two domains of cognition that are linked to higher-order cognition and daily functioning. This study aimed to investigate the near-transfer (transfer of gains to related contexts), far-transfer (transfer of gains to unrelated contexts), and real-world gains associated with WM and PS training in schizophrenia.

METHODS

Eighty-three participants with schizophrenia were recruited and randomly assigned to computerized WM training, PS training, or a no-training control group. Outcome measures included WM, PS, fluid intelligence, executive functioning, social cognition, and daily functioning and symptoms.

RESULTS

PS training led to significant gains in untrained PS tasks, as well as gains in far-transfer tasks that required speed of processing. WM training did not lead to gains in untrained WM tasks and showed inconsistent effects on some far-transfer tasks.

CONCLUSIONS

These results suggest some benefit of domain-specific cognitive training, specifically PS training, in schizophrenia. Far-transfer of gains to other cognitive domains and to real-world functioning may not occur after targeted WM or PS training, though non-specific effects (e.g. through behavioral activation, increased motivation) may lead to improvements in some tasks. Future studies should continue to investigate the mechanisms by which cognitive training may enhance cognition and functioning in schizophrenia.

The efficacy of computerized cognitive drill and practice training for patients with a schizophrenia-spectrum disorder: A meta-analysis

BACKGROUND

Computerized methods for improving cognitive functioning in schizophrenia have gained popularity during the past decades. Therefore, this study evaluates the available evidence for the efficacy of computerized cognitive drill and practice training for patients with schizophrenia-spectrum disorders.

METHODS

A systematic search was carried out using PubMed, Embase, Cochrane Database of Systematic Reviews, and PsycINFO. A meta-analysis was performed to compare cognitive drill and practice training in patients with a schizophrenia-spectrum disorder with non-cognitively oriented control conditions. The primary outcome was cognitive functioning. Secondary outcome measures included psychotic symptoms, depressive symptoms, and functional outcomes. Effect sizes (ES) for all included studies were calculated as Hedges' g.

RESULTS

24 studies were included with 1262 patients in total. Compared to a control condition, patients receiving computerized cognitive drill and practice training showed significantly more improvement on attention (ES = 0.31, p = 0.001), working memory (ES = 0.38, p < 0.001), positive symptoms (ES = 0.31, p = 0.003), and depressive symptoms (ES = 0.37, p = 0.002). Small, marginally significant effect sizes were found for processing speed, verbal and visual learning and memory, and verbal fluency. However, significant effects on functional outcomes and social cognition were absent.

DISCUSSION

The current study showed evidence for the efficacy of computerized cognitive drill and practice training in patients with schizophrenia-spectrum disorders. However, the absence of effects on social cognition and functional outcomes questions the generalization of treatment effects. Together, these results stimulate further development of computerized training programs for schizophrenia that not only improve cognitive functioning, but also generalize cognitive improvement to functional outcomes.

Effects of cognitive remediation therapy versus other interventions on cognitive functioning in schizophrenia inpatients

Computerised cognitive remediation therapy (CCRT) has been shown to improve cognitive function in individuals with schizophrenia beyond effects of other forms of therapy. However, results vary between studies, and most are aimed at individuals who are living in the community. Very few studies have investigated its efficacy in psychiatric wards in order to assess whether or not this is a suitable site to start the therapy. This study evaluated CCRT efficacy among schizophrenia inpatients who received a broad range of therapeutic interventions in a psychiatric ward. A randomised controlled trial of CCRT versus an active control in 66 young inpatients with a diagnosis of schizophrenia was conducted. The intervention lasted for 6 weeks and its efficacy was assessed with the composite score of the MATRICS Consensus Cognitive Battery. Both groups improved similarly in cognitive function and psychopathological symptoms. However, the CCRT group improved more than the controls in negative symptoms. This result shows that providing a drill and practice cognitive remediation to inpatients does not produce benefits for cognitive functioning substantially greater than other forms of therapy provided in a ward, but it is more efficient in reduction of negative symptoms. Our results suggest that CRT might be considered as a promising intervention for reducing negative symptoms in schizophrenia individuals.

Increased integrity of white matter pathways after dual n-back training

Dual n-back WM training has been shown to produce broad transfer effects to different untrained cognitive functions. The task is demanding to the cognitive system because it includes a bi-modal (auditory and visual) dual-task component. A previous WM training study showed increased white matter integrity in the parietal lobe as well as the anterior part of the corpus callosum after visual n-back training. We investigated dual n-back training-related changes in white matter pathways. We anticipated dual n-back training to increase white matter integrity in pathways that connect brain regions related to WM processes. Additionally, we hypothesized that dual n-back training would produce more brain-wide white matter changes than single n-back training because of the involvement of two modalities and the additional dual-task coordination component of the task. The dual n-back training group showed increased white matter integrity (reflected as increased fractional anisotropy, FA) after training. The effects were mostly left lateralized as compared with changes from pretest to posttest in the passive and active control groups. Additionally, significant effects were observed in the anterior part of the corpus callosum, when the training group was compared with the passive control group. There were no changes in pretest to posttest FA changes between the passive and active control groups. The results therefore show that dual n-back training produces increased integrity in white matter pathways connecting different brain regions. The results are discussed in reference to the bi-modal dual-task component of the training task.

A pilot study on the benefit of cognitive rehabilitation in Parkinson's disease

PURPOSE

Patients with Parkinson's disease (PD) show inefficiencies in cognitive performance including working memory functions. Since these problems impact on quality of life and overall well-being, the current study was aimed at improving patients' situations by evaluating the computerized cognitive training tool, BrainStim.

METHOD

A total of 19 healthy controls (HCs) and six patients with PD were included in the study. While all PD patients received cognitive training, the HC sample was subdivided into 12 subjects with training (HC-T) and 10 subjects without (HC-NT). Participants underwent a double baseline assessment, a post-training assessment, and a 3-month follow up on neuropsychological tests and self-report measures on fatigue and depression. Training was administered between the second baseline and postassessment. It comprised 16 supervised sessions according to a standardized training protocol over 4 weeks.

RESULTS

Significant improvements in verbal and visuospatial short-term and long-term memory were found in both training groups. In addition, the HC-T improved on mental speed, and verbal and visuospatial working memory. Both training groups showed stable results for all short-term visuospatial measures after 3 months. Further, the HC-T showed stable results for working memory, verbal, and visuospatial short-term and long-term memory.

CONCLUSIONS

The efficacy of the applied computerized cognitive training tool BrainStim could be verified in patients with PD and healthy age-matched controls. The preliminary findings highlighted the suitability of a specific cognitive intervention to improve cognitive inefficiencies in patients with PD as well as in healthy older people. Further research on cognitive training in combination with PD drug therapy is needed to better understand the mutual interaction and to offer optimal therapeutic approaches to patients.

Working memory and processing speed training in schizophrenia: study protocol for a randomized controlled trial

BACKGROUND

In most domains of cognition, individuals with schizophrenia are generally found to be one standard deviation below the mean of the controls. As a result, examining the impact of cognitive remediation in individuals with schizophrenia has been a burgeoning area of research. However, the state of the literature remains unclear as to which domains of cognition should be targeted to produce the most widespread and durable benefits for individuals with schizophrenia. One suggestion is that targeting lower-level cognitive processes that are important for higher-level and more complex aspects of cognition may produce the most widespread benefits in cognition and everyday functioning. Relatively few studies have examined the effects of working memory or processing speed training in schizophrenia, as most studies examine broad-based remediation programs. Thus, a need exists for targeted working memory and processing speed training studies to better understand the mechanisms of cognitive enhancement in patients. This study aims to 1) investigate near-transfer gains (that is, the transfer of learning to related contexts) associated with working memory and processing speed training in schizophrenia patients; 2) investigate far-transfer gains (that is, the transfer of learning to new contexts) associated with working memory and processing speed training (that is, gains in other neurocognitive domains and social cognition); and 3) investigate real-world gains associated with training (that is, gains in daily functioning).

METHODS/DESIGN

A double-blind randomized controlled trial with a three parallel group design will be conducted. A random sample of 81 patients with schizophrenia or schizoaffective disorder will be recruited through outpatient clinics at Foothills Hospital and community support programs in Calgary, Alberta. Participants will be randomly assigned using a computer-generated program in a 1:1:1 ratio to a working memory-training group, a processing speed-training group, or a no-training control group. Training will be completed at home for 30 minutes per day, 5 days per week, for a total of 10 weeks. Neurocognitive, social cognitive, and daily functioning measures will be administered both pre- and post-training to detect training-related gains. The primary outcome measures will include working memory and processing speed (near-transfer measures), as well as fluid intelligence (far-transfer measure).

TRIAL REGISTRATION

Current controlled trials NCT02478827 (ClinicalTrials.gov, registered on 15 June 2015).

Computerised working-memory focused cognitive remediation therapy for psychosis--A preliminary study

BACKGROUND

Cognitive deficits are a core feature of schizophrenia and related psychotic disorders and are associated with decreased levels of functioning. Behavioural interventions have shown success in remediating these deficits; determining how best to maximise this benefit while minimising the cost is an important next step in optimising this intervention for clinical use.

AIMS

To examine the effects of a novel working-memory focused cognitive remediation (CR) training on cognitive difficulties based on internet delivery of training and weekly telephone support.

METHOD

Participants with a diagnosis of psychosis (n=56) underwent either 8 weeks of CR (approximately 20 h) or 8 weeks of treatment as usual (TAU). General cognitive ability, working memory and episodic memory were measured both pre and post intervention for all participants.

RESULTS

In addition to improvements on trained working memory tasks, CR training was associated with significant improvements in two tests of verbal episodic memory. No association between CR and changes in general cognitive ability was observed. Effect sizes for statistically significant changes in memory were comparable to those reported in the literature based primarily on 1:1 training.

CONCLUSIONS

The cognitive benefits observed in this non-randomised preliminary study indicate that internet-based working memory training can be an effective cognitive remediation therapy. The successes and challenges of an internet-based treatment are discussed.

Working memory training triggers delayed chromatin remodeling in the mouse corticostriatothalamic circuit

Working memory is a cognitive function serving goal-oriented behavior. In the last decade, working memory training has been shown to improve performance and its efficacy for the treatment of several neuropsychiatric disorders has begun to be examined. Neuroimaging studies have contributed to elucidate the brain areas involved but little is known about the underlying cellular events. A growing body of evidence has provided a link between working memory and relatively long-lasting epigenetic changes. However, the effects elicited by working memory training at the epigenetic level remain unknown. In this study we establish an animal model of working memory training and explore the changes in histone H3 acetylation (H3K9,14Ac) and histone H3 dimethylation on lysine 27 (H3K27Me2) triggered by the procedure in the brain regions of the corticostriatothalamic circuit (prelimbic/infralimbic cortex (PrL/IL), dorsomedial striatum (DMSt) and dorsomedial thalamus (DMTh)). Mice trained on a spontaneous alternation task showed improved alternation scores when tested with a retention interval that disrupts the performance of untrained animals. We then determined the involvement of the brain areas of the corticostriatothalamic circuit in working memory training by measuring the marker of neuronal activation c-fos. We observed increased c-fos levels in PrL/IL and DMSt in trained mice 90min after training. These animals also presented lower immunoreactivity for H3K9,14Ac in DMSt 24h but not 90min after the procedure. Increases in H3K27Me2, a repressive chromatin mark, were found in the DMSt and DMTh 24h after the task. Altogether, we present a mouse model to study the cellular underpinnings of working memory training and provide evidence indicating delayed chromatin remodeling towards repression triggered by the procedure.

Working memory training in schizophrenia and healthy populations

Cognitive deficits are consistently demonstrated in individuals with schizophrenia. Cognitive training involves structured exercises prescribed and undertaken with the intention of enhancing cognitive abilities such as attention, memory, and problem solving. Thus, cognitive training represents a potentially promising intervention for enhancing cognitive abilities in schizophrenia. However, cognitive training programs are numerous and heterogeneous, hence, the generalizability of training related outcomes can be challenging to assess. This article will provide a brief overview of current literature on cognitive training and explore how knowledge of working memory training in healthy populations can potentially be applied to enhance cognitive functioning of individuals with schizophrenia.

Executive function processes mediate the impact of working memory impairment on intelligence in schizophrenia

OBJECTIVE

The study investigated working memory, executive functions (conceptualized as response inhibition, updating, and shifting), and intelligence in schizophrenia, using structural equation modelling to determine the relationship between working memory and intelligence, testing whether specific executive functions act as a mediator for the association.

METHOD

One hundred and twenty-five individuals diagnosed with schizophrenia and 64 healthy participants were included in the study, tested using measures of working memory, intelligence and executive functioning. Structural equation modelling (SEM) was used to estimate direct and indirect associations between main measures.

RESULTS

The schizophrenia group had significantly lower working memory, executive function and intelligence than the healthy group. The relationship between working memory and intelligence was significantly mediated by inhibition, updating and shifting functions.

CONCLUSION

The study indicates a mediating role of executive functions in determining the association between working memory and intellectual function in schizophrenia. It is further proposed that in people with schizophrenia, cognitive remediation approaches targeting working memory through executive functioning may in turn improve intellectual function generally.