The impact of cognitive reserve on neurocognitive performance in Major Depressive Disorder

Cognitive reserve and cognition in mood disorders: A systematic review and meta-analysis

Cognitive functioning heterogeneity is a well-recognized phenomenon in individuals diagnosed with mood disorders. Cognitive Reserve (CR) has been linked to multiple positive outcomes, including cognitive performance in these patients. This systematic review and meta-analysis aim to provide a comprehensive analysis of the relationship between CR and cognitive functioning in individuals with mood disorders, including bipolar disorder and depressive disorders. Following PRISMA guidelines, a systematic review and meta-analysis was conducted of original research exploring the relationship between CR and cognitive performance in adult individuals with mood disorders. The literature search was conducted on PubMed, Scopus, and Web of Science, from 2002 to September 2023, and the Newcastle-Ottawa Scale (NOS) was used to evaluate the quality of studies. Overall, 17 studies met the inclusion criteria for the systematic review and 11 for the meta-analysis. Both qualitative and quantitative findings suggested a positive relationship between CR measures and cognitive domains. CR emerges as a possible protective factor for cognitive functioning in adult individuals with mood disorders, potentially helping to mitigate the cognitive impairments associated with the disorder. These findings underscore the importance of the fact that promoting and enhancing CR could help in the cognitive prognosis of this population.

Which variables moderate the relationship between depressive symptoms and global neurocognition across adulthood?

The current study examined moderators of the relationship between depressive symptoms and global neurocognition in a large non-clinical community-dwelling sample spanning adulthood. Participants comprised 5,430 individuals between the ages of 18-99 years drawn from the Virginia Cognitive Aging Project. Depressive symptoms were measured via the Center for Epidemiologic Studies-Depression scale and neurocognition was operationalized as a composite variable comprising episodic memory, spatial visualization, processing speed, and reasoning tasks. Moderator variables included physical activity, cognitive activity, education, emotional stability, and openness. Hierarchical regressions were used to examine the influence of depressive symptoms and the moderators on neurocognition. Depressive symptoms significantly predicted neurocognition. Cognitive activity, years of education, and emotional stability moderated the depression-neurocognition relationship by buffering the impact of depressive symptoms on neurocognition. Cognitive activity engagement and level of education may function as a protective influence on those with higher levels of depressive symptoms, while emotional stability may be protective for individuals with lower levels of depressive symptoms. No differences in moderation were found across three age groups representing younger, middle, and older adults. Post-hoc analyses showed years of education and openness as moderators in a subsample excluding individuals with potentially clinically meaningful levels of depressive symptoms.

Psychometric Properties of the Chinese Version of the ElectroConvulsive Therapy Cognitive Assessment: An Electroconvulsive Therapy-Specific Cognitive Screening Tool

OBJECTIVES

Electroconvulsive therapy (ECT) is an effective somatic treatment, but it may be limited by cognitive adverse effects. The existing cognitive screening instruments often lack specificity to ECT-associated cognitive deficits. The ElectroConvulsive Therapy Cognitive Assessment was developed and validated in a clinical setting, but the reliability and validity of the Chinese version of ElectroConvulsive Therapy Cognitive Assessment (ECCA-C) have not been studied in a large clinical sample.

METHODS

The ECCA-C and the Montreal Cognitive Assessment (MoCA) were administered to patients with major depressive disorder (MDD) undergoing ECT at 3 time points: pretreatment (baseline), before the fifth treatment, and 1 week posttreatment. The instruments were also administered to a sample of healthy subjects.

RESULTS

Sixty-five patients with MDD and 50 age- and sex-matched healthy controls were recruited in this study. Overall, the patient group had statistically significantly lower MoCA and ECCA-C scores than the control group (both P values <0.001). The Cronbach α of the ECCA-C was 0.88 at baseline. Statistically significant decreases over time were observed in ECCA-C: pre-ECT (23.9 ± 4.0) > mid-ECT (21.3 ± 3.4) > post-ECT (18.7 ± 4.8) (all P values <0.001), whereas no statistically significant changes in MoCA scores were found at these 3 time points (F = 1.86, P = 0.165). A cutoff score of 26.5 on the ECCA-C was found to best differentiate between MDD patients and healthy controls.

CONCLUSIONS

The ECCA-C showed satisfactory psychometric properties and may be a more sensitive instrument than the MoCA to assess cognitive impairment associated with ECT.

Cognitive Reserve Moderates the Effects of Fatigue and Depressive Symptoms in Multiple Sclerosis

To investigate cognitive reserve as a possible moderator in the relationship between fatigue and depressive symptoms in persons with multiple sclerosis (PwMS). Fifty-three PwMS (37 female; mean age, 52.66; mean education, 14.81) completed comprehensive neuropsychological testing and psychosocial questionnaires assessing the perceived effects of fatigue (Fatigue Impact Scale) and depressive symptoms (Beck Depression Inventory-Fast Screen). Cognitive reserve (CR) was operationalized as Fixed CR and Malleable CR. Fixed CR was quantified as the standardized mean of years of education and a vocabulary-based estimate of premorbid intelligence. Malleable CR was quantified as the standardized mean of cognitive exertion, exercise, and socializing items from the Cognitive Health Questionnaire. Regressions on depressive symptoms examining fatigue, both conceptualizations of CR, and their interactions were explored. A Bonferroni correction was used; results were considered significant at an alpha level of p < .01. The interactions between fatigue and both conceptualizations of CR were significant, p = .005 (Fixed CR); p = .004 (Malleable CR). Simple effects tests revealed that fatigue only predicted depressive symptoms in PwMS with low Fixed CR or low Malleable CR (p's < .001), and not in those with high Fixed or high Malleable CR (p > .01). Cognitive reserve moderated the relationship between fatigue and depressive symptoms in PwMS. Specifically, fatigue does not appear to influence depression in PwMS with high cognitive reserve. Having higher cognitive reserve (either Fixed or Malleable) may reduce the likelihood that fatigue will lead to depressive symptoms in MS.

Factors associated with objective and subjective cognitive impairment in Chinese patients with acute major depressive disorder

BACKGROUND

Patients diagnosed withmajor depressive disorder (MDD) usually experience impaired cognitive functioning, which might negatively impact their clinical and functional outcomes. This study aimed to investigate the association of specific clinical factors with cognitive dysfunction in a group of MDD patients.

METHODS

A total of 75 subjects diagnosed with recurrent MDD were evaluated during the acute stage. Their cognitive functions were assessed using the THINC-integrated tool (THINC-it) for attention/alertness, processing speed, executive function, and working memory. Clinical psychiatric evaluations, such as the Hamilton Anxiety Scale (HAM-A), the Young Mania Rating Scale (YMRS), the Hamilton Depression Scale (HAM-D), and the Pittsburgh Sleep Quality Index(PSQI), were used to assess patients' levels of anxiety, depression and sleeping problems. The investigated clinical variables were age, years of education, age at onset, number of depressive episodes, disease duration, presence of depressive and anxiety symptoms, sleep problems, and number of hospitalizations.

RESULTS

The results revealed that significant differences were observed between the two groups in the THINC-it total scores, Spotter, Codebreaker, Trails, and PDQ-5-D scores (P < 0.001). The THINC-it total scores, Spotter, Codebreaker, Trails, and Symbol Check were significantly associated with age and age at onset(P < 0.01). In addition, regression analysis found that years of education was positively associated with the Codebreaker total scores (P < 0.05). the THINC-it total scores, Symbol Check, Trails, and Codebreaker were correlated with the HAM-D total scores(P < 0.05). Additionally, the THINC-it total scores, Symbol Check, PDQ-5-D and Codebreaker significantly correlated with the PSQI total scores (P < 0.05).

CONCLUSION

We found a significant statistical association between almost all cognitive domains and different clinical aspects in depressive disorder, such asage, age at onset, severity of depression, years of education, and sleep problems. Additionally, education was shown to be a protective factor against processing speed impairments. Special considerations of these factors might help outline better management strategies to improve cognitive functions in MDD patients.

Predicting normative data in healthy individuals on the computerized wisconsin card sorting test using regression models

BACKGROUND

Computerized neuropsychological tests provide advantages to clinicians with cost, administration, and time. However, studies have pointed out performance differences between manual and computerized versions of some neuropsychological tests. One of these is the Wisconsin Card Sorting Test (WCST). Due to the performance difference, the normative data of manual tests cannot be used for their computerized versions. Therefore, normative data searches are needed for computerized versions.

OBJECTIVE

This study aimed to determine the norm values of WCST-CV in a healthy sample.

METHODS

422 healthy adults aged 18-78 participated in this study. WCST-CVsub-scores are modeled by Regression Analysis based on Age and Education level to generate normative data. Among the 13 WCST scores, the regression models for WCST 2, WCST 3, WCST 4, WCST 10, and WCST 11 are significant. WCST 2, WCST 4, and WCST 11 scores are estimated with Ordinary Least Squares (OLS). However, WCST 3 and WCST 10 scores are estimated with Weighted Least Squares (WLS) due to the violation of the homoscedasticity assumption.

RESULTS

The regression results show that p-values calculated from error increase as age and education level increase.

CONCLUSION

As a result of our research, norm values between 18-78 years of age were produced using RA. It was determined that gender was not significant for any sub-score. Therefore, only age and education level from socio-demographic variables were included in the model.

The relationship between cognitive reserve and cognition in healthy adults: a systematic review

The concept of Cognitive Reserve (CR) refers to the individual differences allowing some people to cope better with brain pathology. The aim of the present review was to explore the relationship between CR and cognition in adulthood. This association has been addressed in several neuro(psycho)logical disorders and in healthy elderly people. However, few studies explored this issue in adulthood (age range 18–65), when individuals might take advantage the most from psychoeducational approaches aimed at increasing CR. For our systematic review, we selected studies assessing CR and adopting neuropsychological and experimental tasks for evaluation of cognitive functioning in healthy individuals. In the selected articles, we examined the relationship of singular proxies, composite indexes or standardized scales of CR with measures of general cognition, attention, inhibitory control, verbal fluency, constructional abilities, and verbal and spatial memory. The results suggested a positive relationship between singular CR proxies, composite indexes or standardized scales, and almost all the explored cognitive domains. No clear conclusion could be made on constructional abilities due to the scarcity of available studies. CR seems associated with better cognitive performance in adulthood, but definite methodological improvements and the use of standardized scales for CR are necessary to reduce inconsistencies among studies.

The effect of second-generation antidepressant treatment on the attention and mental processing speed of patients with major depressive disorder: A meta-analysis study with structural equation models

Major depressive disorder (MDD) has been linked to attention and mental processing speed deficits that can be improved after pharmacological treatment. However, it is unclear whether a class of antidepressants is more effective than others to ameliorate these deficits in MDD. Additionally, the possible effects of clinical and demographic variables on improving MDD attention and processing speed deficits after antidepressant treatment are unknown. We aimed to study the possible neuropsychological effects of second-generation antidepressant classes on the attention and processing speed of MDD patients and the potential influences of clinical and demographic variables as moderators of these effects using a meta-analytic approach. Twenty-five papers were included in our study. A structural equation model meta-analysis was performed. The improvement of attention and processing speed after pharmacological treatment is clinically relevant but incomplete. Selective serotonin reuptake inhibitors (SSRIs) and dual inhibitors are the drugs causing the greatest improvement in the processing speed of MDD patients. Antidepressant class is an important variable linked to processing speed improvement after MDD treatment. However, the degree of improvement in both cognitive functions is strongly influenced by some clinical and demographic variables of depressed patients, such are age and education of the MDD patients, the duration of the antidepressant treatment, and the depression status of the patients.

Dealing with heterogeneity of cognitive dysfunction in acute depression: a clustering approach

BACKGROUND

Heterogeneity in cognitive functioning among major depressive disorder (MDD) patients could have been the reason for the small-to-moderate differences reported so far when it is compared to other psychiatric conditions or to healthy controls. Additionally, most of these studies did not take into account clinical and sociodemographic characteristics that could have played a relevant role in cognitive variability. This study aims to identify empirical clusters based on cognitive, clinical and sociodemographic variables in a sample of acute MDD patients.

METHODS

In a sample of 174 patients with an acute depressive episode, a two-step clustering analysis was applied considering potentially relevant cognitive, clinical and sociodemographic variables as indicators for grouping.

RESULTS

Treatment resistance was the most important factor for clustering, closely followed by cognitive performance. Three empirical subgroups were obtained: cluster 1 was characterized by a sample of non-resistant patients with preserved cognitive functioning (n = 68, 39%); cluster 2 was formed by treatment-resistant patients with selective cognitive deficits (n = 66, 38%) and cluster 3 consisted of resistant (n = 23, 58%) and non-resistant (n = 17, 42%) acute patients with significant deficits in all neurocognitive domains (n = 40, 23%).

CONCLUSIONS

The findings provide evidence upon the existence of cognitive heterogeneity across patients in an acute depressive episode. Therefore, assessing cognition becomes an evident necessity for all patients diagnosed with MDD, and although treatment resistant is associated with greater cognitive dysfunction, non-resistant patients can also show significant cognitive deficits. By targeting not only mood but also cognition, patients are more likely to achieve full recovery and prevent new relapses.

Cognitive reserve may outperform age, mood and psychiatric comorbidities as a predictor of executive functioning in bipolar disorder and healthy adults

INTRODUCTION

Cognitive reserve plays a protective role against executive dysfunction in healthy adults and individuals with psychiatric illnesses such as bipolar disorder. However, the magnitude of the influence of cognitive reserve on specific executive functions (EFs), and its impact relative to variables such as depressive symptoms, age and psychiatric comorbidities, is unexplored. This study aimed to quantify the influence of cognitive reserve on specific EFs, and compare its impact with that of depressive symptoms, age and psychiatric comorbidities, in separate models for patients with bipolar disorder and healthy adults.

METHOD

This was a cross-sectional study of 121 adults with no mood disorders and 109 with bipolar disorder, all of whom underwent a comprehensive psychiatric assessment and evaluation of the EFs. Cognitive reserve was measured using years of education, IQ and reading and writing habits. The association between EFs and predictors (cognitive reserve, depressive symptoms, age and psychiatric comorbidities) was evaluated through structural equation modeling. Four models were constructed for each group independently (bipolar disorder and control), one each for working memory, verbal fluency, inhibition and flexibility, due to group differences in age and cognitive reserve.

RESULTS

Working memory, inhibition and flexibility were most significantly predicted by cognitive reserve and age. Verbal fluency was only predicted by cognitive reserve. Comorbidities and depressive symptoms were not significant in any of the models. Cognitive reserve had a positive influence on all EFs in models for patients with bipolar disorder and models for control participants. Age had a negative impact on three of the four EFs tested.

CONCLUSION

Fostering cognitive reserve through continued education and cognitively stimulating leisure activities may be an effective intervention for executive dysfunction in patients and non-patients alike. In some cases, the effects of these interventions may outweigh the negative cognitive impact of aging, depressive symptoms and psychiatric conditions.

Is there a combined effect of depression and cognitive reserve on cognitive function? Findings from a population-based study

OBJECTIVE

To analyse the combined effect of depression and cognitive reserve (CR) on cognition over a three-year follow-up period; and to explore this relationship specifically in individuals aged 65+ years.

DESIGN

Data from the 'Edad con Salud' project were analysed (n = 1,144; 50+ years).

MAIN OUTCOME MEASURES

The Composite International Diagnostic Interview was used to evaluate depression. CR was assessed with the Cognitive Reserve Questionnaire. Episodic memory was assessed with the word list memory and recall. Verbal fluency was measured through the animal naming task. Random coefficient regression analyses were performed.

RESULTS

Depression was associated with lower scores in episodic memory, whereas increased levels of CR were related with higher scores across all the cognitive tests. Among older-aged individuals, cognition decreased at lower levels of CR regardless of depression, while participants with depression exhibited decreased values in both measures of memory at higher levels of CR.

CONCLUSION

Depression and CR were related with cognitive performance. Among older individuals, those with low levels of CR may constitute a vulnerable group with poor cognitive prognosis, whilst a harmful effect of depression on memory performance was observed among individuals with greater CR. Further evidence needs to be gathered to understand these associations.

Age at illness onset and physical activity are associated with cognitive impairment in patients with current diagnosis of major depressive disorder

BACKGROUND

Cognitive impairment has been reported in patients with Major Depressive Disorder (MDD). This study aims to explore the association between lifestyle habits and health-related factors and the presence of cognitive symptoms in MDD patients.

METHODS

Demographic, clinical, health-related variables and cognitive scores measured with the Cambridge Neuropsychological Test Automated Battery (CANTAB) were compared between 74 patients with current MDD and 68 healthy controls (HC). To test the hypothesis of associated factors to cognitive symptoms, multivariate backward stepwise linear regression models were run.

RESULTS

Significant neuropsychological deficits were evident in MDD compared with HC in the global cognitive index (F=8.29; df=1, 140; p=0.005). In the regression analysis performed on MDD and HC, years of schooling (β=-0.11; p=<0.001), job status (β=-0.50; p=0.016), physical activity (β=-0.25; p=0.04) and age at illness onset (β=0.17; p=0.017) were statistically significant factors associated to cognitive impairment. The regression model ran in HC showed that only years of schooling were significant (β=-0.07; p=<0.001) in this group.

LIMITATIONS

Sample size was relatively small. Everyday cognitive skills were not evaluated.

CONCLUSIONS

MDD patients have cognitive deficits. These deficits are linked with the years of education, job status, age of onset of the disease and the performance of physical activity. These results support the importance of the implementation of interventions targeting the cognitive reserve and lifestyle habits of MDD patients, in addition to the conventional therapeutic approach focused on symptoms control.

Predictors of Long-Term Improvement Following Cognitive Remediation in a Sample With Elevated Depressive Symptoms

Objective

Cognitive remediation (CR) techniques (interventions to enhance cognitive functioning) have proven moderately effective in improving cognition and daily functioning in major depressive disorder (MDD). However, baseline predictors of treatment response are lacking. The present study aimed to identify factors influencing long-term CR outcomes in a sample with current or previous, mild or moderate MDD and with self-reported cognitive deficits.

Methods

Forty-two completers of group-based CR (strategy learning or drill-and-practice), were pooled into one sample. Based on change scores from baseline to 6-month follow-up, participants were categorized as “improvers” or “non-improvers” using reliable change index calculations. Measures included a questionnaire of everyday executive functioning and a neuropsychological test of attention. Finally, improvers and non-improvers were compared in terms of various sociodemographic, psychological, illness-related, and neuropsychological baseline variables.

Results

Seventeen participants improved reliably in everyday executive functioning, and fourteen demonstrated a reliable improvement in attention. No statistically significant differences emerged between improvers and non-improvers.

Conclusion

No major predictors of CR were identified. Importantly, the current findings are insufficient to guide clinical decision-making. Large-scale studies with a priori hypotheses are needed to make advances in the future.

Goal management training as a cognitive remediation intervention in depression: A randomized controlled trial

BACKGROUND

Major depressive disorder (MDD) is associated with deficits in executive functioning (EF) that may have a detrimental effect on everyday functioning. Despite this, there are no established cognitive remediation interventions available targeting EF in MDD. Hence, the primary aim of the present pre-registered randomized controlled trial was to evaluate the effectiveness of Goal Management Training (GMT), a metacognitive and strategy-based cognitive remediation intervention to improve EF in MDD.

METHODS

Sixty-three participants with current or previous mild or moderate MDD and self-reported executive deficits were included and randomized to nine sessions of either GMT (two hours, once weekly; n = 35) or computerized cognitive training (one hour, twice weekly; n = 28). Assessments were conducted at baseline (T1), immediately following training (T2), and at six-month follow-up (T3). The primary outcome measure was The Behavior Rating Inventory of Executive Function - Adult version, pertained to daily life EF. Secondary outcome measures included additional EF assessments (performance-based measures and questionnaires), and depressive symptom severity.

RESULTS

Forty-three participants completed treatment. Both groups improved following training, and linear mixed model analyses revealed no statistically significant differences between the groups for any outcome measure. Additional exploratory within-group analyses revealed a statistically significant reduction of everyday executive dysfunction and reduced depressive symptoms at the six-month follow-up in GMT only.

LIMITATIONS

The study was single-blind, and the sample size was modest.

CONCLUSIONS

Our findings indicate comparable improvements in everyday and performance-based measures of EF, in addition to reductions in depressive symptoms following both GMT and CCT.

The effects of cognitive reserve and depressive symptoms on cognitive performance in major depression and bipolar disorder

BACKGROUND

Significant heterogeneity is observed in the cognitive profiles of bipolar disorder (BD) and major depression (MDD), characterized in part by differences in individual and clinical variables such as cognitive reserve (CR) and depression severity. However, no other study evaluated how this variables may interact regarding neurocognitive functioning. The aim of the present exploratory study was to evaluate the interaction between different depressive symptoms severity, CR and diagnosis with neurocognitive functioning.

METHOD

202 participants (MDD=91; BD=111) classified either as euthymic, with mild depression or moderate to severe depression, and low or high CR completed a neuropsychological evaluation of verbal fluency, working memory (WM), inhibitory control (IC), cognitive flexibility (CF) and attention (Att).

RESULTS

Neuroprotective effects of CR were observed in patients with BD within a major depressive episode in WM, IC, FC and Att. In MDD, CR acted as a neuroprotective factor during euthymia and moderate to severe depression in the same cognitive functions. CR and depression severity differentiated the cognitive profiles of individuals with BD and MDD.

LIMITATIONS

Some variables related to neurocognitive performance like medication use, number of mood episodes, illness duration or previous hospitalizations were not controlled.

CONCLUSION

CR may be protective against cognitive impairment in both BD and MDD, and these effects were observed in euthymia and during depressive episodes of varying severity. These findings highlight the importance of investigating such variables in the neuropsychological evaluation of mood disorders, which may help to understand the cognitive heterogeneity within these populations.

Age, Education and Intellectual Quotient Influences: Structural Equation Modeling on the study of Benton Visual Retention Test (BVRT)

This study searched for sociodemographic influences on visual memory and visuoconstructive ability in healthy and clinical samples evaluated with Benton Visual Retention Test (BVRT) in two studies. In Study 1, we searched for changes related to age in children, adolescents, adults and elderly on the performance of the BVRT. In Study 2, we investigated the relations among age, years of education and intellectual quotient (IQ) on the performance of the BVRT using Structural Equation Modeling (SEM). Participants were 624 individuals aged between six and 89 years old (M = 25.40; SD = 22.34) from the normatization and evidence validity studies at Brazil. We used a sociodemographic questionnaire, BVRT and IQ measure was estimated. Study 1 has shown a performance similar to the developmental graphics with a U-inverted pattern in relation to age: An increase of the visual memory ability in the children and adolescent groups as age increases, a tendency of a decrease in the performance in the adult group that intensifies in the elderly group. Study 2 found that the model for the BVRT performance tested by SEM denoted satisfactory goodness-of-fit indexes, χ2/gl = 2.67, p < .001; CFI = .92; TLI = .93; RMSEA = .004, 90% CI = [.03, .05];WLSMV = 1.79, and corroborated the theoretical assumption. The SEM model confirmed in this study highlight the strong role of years of education in the prediction of BVRT scores.

Classification of cognitive reserve in healthy older adults based on brain activity using support vector machine

OBJECTIVE

Cognitive reserve (CR) refers to the capacity of the brain to actively cope with damage via the implementation of remedial cognitive processes. Traditional CR measurements focus on static proxies, which may not be able to appropriately estimate dynamic changes in CR. This study therefore investigated the cognitive performance and characteristics of brain activity of low- and high-CR healthy adults during resting and n-back task states and categorized subjects according to magnetoencephalographic (MEG) information using a support vector machine (SVM) classifier.

APPROACH

Forty-one volunteers were divided into groups with low and high CR indexes based on their education, occupational attainment, leisure and social activities.

MAIN RESULTS

The results can be summarized as follows. First, subjects with a higher CR had higher accuracies and faster reaction times in the task. Second, subjects with a lower CR had a higher M300 intensity but a constant M300 latency. Third, subjects with a higher CR had a higher beta intensity in the parietal and occipital regions during the task, whereas subjects with a higher CR had a higher gamma intensity in the right temporal region in the resting state. Finally, subjects with a higher CR had negative gamma asymmetry between the right and left occipital regions, whereas subjects with a lower CR had positive values in the resting state.

SIGNIFICANCE

These MEG results were subsequently used to classify subjects into high-/low-CR subjects using an SVM classifier, and a mean accuracy of 88.89% was obtained. This objective and nonstatic method for determining CR level warrants further research for a wider variety of future clinical applications.

The effects of cognitive reserve on predicting and moderating the cognitive and psychosocial functioning of patients with bipolar disorder

BACKGROUND

Cognitive reserve (CR) reflects the resilience of the brain to cope with neuropathological changes and minimize clinical manifestations. In the present study, we explore the association between CR and cognitive and psychosocial functioning, and examined the potential moderating role of CR in patients with bipolar disorder (BD).

METHODS

One hundred and twenty-five outpatients with BD type I and sixty healthy individuals were recruited. All participants were assessed with a neuropsychological battery examining attention and processing speed, working memory, visual memory and executive functioning, the Global Assessment of Functioning scale and the Cognitive Complaints in Bipolar Disorder Rating Assessment. Proxies for cognitive reserve included premorbid intelligence and educational level.

RESULTS

Patients with bipolar disorder presented with worse cognitive performance and psychosocial functioning than healthy controls. Multiple regression models revealed that educational level negatively associated with all assessed domain-specific cognition scores and premorbid intelligence predicted attention and processing speed and psychosocial functioning. Notably, premorbid intelligence significantly moderated the associations between the number of episodes (total, hypo/manic and depressed) and neurocognitive functioning, and the educational level also moderated the relationships between the numbers of hypo/manic and total episodes and subjective cognitive functioning.

CONCLUSIONS

Cognitive reserve contributes to functional outcomes in patients with BD and may emerge as a key factor contributing to the course and prognosis of patients with BD. In the future, cognitive reserve must be considered in both research and clinical interventions related to bipolar disorder.

Testing whether cognitive reserve as measured by self-rating of stimulating activities moderates the association of polysubstance use and neurocognitive disorder

Introduction: The objectives were to identify a latent factor of cognitive reserve (CR) assessed by self-rating of cognitively stimulating activities, to analyze the association between this factor and educational attainment, and to test whether CR moderates the association between polysubstance use and neurocognitive disorder (NCD). Methods: Cross-sectional data of 753 participants was collected in Mexico City. A questionnaire for self-rating of stimulating activities (work/education, leisure, physical, social, usual- and current environments) was designed. Confirmatory factor analysis was performed to test unifactoriality. This CR factor was then used within a structural equation model of moderation between recent- and years of substance use and indicators of NCD (Montreal Cognitive Assessment and an interview for subjective cognitive deficits). Results: We found acceptable goodness-of-fit values for the unifactorial model, but no association of this factor with educational attainment, nor with recent- and years of substance use (suggesting independence of CR and severity of neuropathology). We did not find a moderation effect of CR between substance use and indicators of NCD; CR was negatively associated with subjective cognitive deficits only. Conclusions: Moderation effect of self-rated CR should be further tested using direct measures of substance-induced neuropathology. Measurement of self-rated CR may complement self-reported cognitive examination.

Cognitive reserve-mediated neural modulation of emotional control and regulation in people with late-life depression

Late-life depression (LLD) is an affective disorder that is highly prevalent among older people. Cognitive reserve (CR) refers to an active process that facilitates the flexibility and efficiency of the neural networks to compensate for impairments that emerge in consequence of brain pathology. The current functional magnetic resonance imaging study investigated whether and how CR affects emotional regulation, level of depression severity and neural activity associated with affective control during emotional Stroop (eStroop) task. Altogether, 90 older people participated in this study, 50 of whom suffered from LLD. We used years of education and verbal fluency capacity as proxies for CR. Clinical participants with relatively higher CR presented with milder degrees of depression, better eStroop performance and stronger neural activity in the middle frontal gyrus (MFG) involved with exercising affective control. Results of the mediation analysis indicated that both education and verbal fluency significantly mediated the association between the depression severity and MEG activity. These results suggest a negative association between CR and age-related clinical symptoms of emotional dysregulation. Our neurobehavioral findings provide supportive evidence that CR implies efficiency of top-down emotional regulation and operates as a protective factor against emotional and cognitive vulnerability in the aging brain.