Memory complaints in epilepsy: An examination of the role of mood and illness perceptions

Statistical learning in epilepsy: Behavioral and anatomical mechanisms in the human brain

OBJECTIVE

Statistical learning, the fundamental cognitive ability of humans to extract regularities across experiences over time, engages the medial temporal lobe (MTL) in the healthy brain. This leads to the hypothesis that statistical learning (SL) may be impaired in patients with epilepsy (PWE) involving the temporal lobe, and that this impairment could contribute to their varied memory deficits. In turn, studies done in collaboration with PWE, that evaluate the necessity of MTL circuitry through disease and causal perturbations, provide an opportunity to advance basic understanding of SL.

METHODS

We implemented behavioral testing, volumetric analysis of the MTL substructures, and direct electrical brain stimulation to examine SL across a cohort of 61 PWE and 28 healthy controls.

RESULTS

We found that behavioral performance in an SL task was negatively associated with seizure frequency irrespective of seizure origin. The volume of hippocampal subfields CA1 and CA2/3 correlated with SL performance, suggesting a more specific role of the hippocampus. Transient direct electrical stimulation of the hippocampus disrupted SL. Furthermore, the relationship between SL and seizure frequency was selective, as behavioral performance in an episodic memory task was not impacted by seizure frequency.

SIGNIFICANCE

Overall, these results suggest that SL may be hippocampally dependent and that the SL task could serve as a clinically useful behavioral assay of seizure frequency that may complement existing approaches such as seizure diaries. Simple and short SL tasks may thus provide patient-centered endpoints for evaluating the efficacy of novel treatments in epilepsy.

Influence of psychological factors on the relationship between subjective and objective memory in adults with pharmacoresistant temporal lobe epilepsy

PURPOSE

Many adults with temporal lobe epilepsy (TLE) report subjective cognitive impairment; however, prior studies have shown a discrepancy between these subjective complaints and objective cognitive deficits on neuropsychological measures. Mood disorders/symptoms are also common in TLE and have been linked to greater subjective cognitive difficulties. To further understand these relationships, this retrospective study sought to determine if symptoms of depression and anxiety moderate or mediate the relationship between subjective cognitive impairment and objective cognitive performance in adults with TLE.

METHOD

Participants were 345 adults (mean age = 40.7; 55 % female) with pharmacoresistant TLE who completed self-report screening measures of depression, anxiety, and subjective cognitive function along with objective memory measures as part of a pre-surgical clinical neuropsychological evaluation. A series of linear regression analyses was conducted to examine the potential moderating and mediating effects of mood on the relationship between subjective and objective memory function after adjusting for relevant covariates.

RESULTS

Consistent with existing literature, self-reported depression and anxiety symptoms were significantly correlated with subjective memory difficulties across all scales (all p < .001). Subjective memory impairment was also significantly correlated with objective memory performance on neuropsychological measures, albeit with small effect sizes (estimate range 0.04-0.20). Contrary to our hypothesis, depression and anxiety did not moderate or mediate the relationship between subjective memory complaints and objective memory performance.

CONCLUSIONS

While symptoms of depression and anxiety were associated with subjective memory ability in this cohort of adults with TLE, this study suggests that mood symptoms do not fully explain the relationship between subjective and objective memory function, likely reflecting the complex and multifactorial relationships among these variables. Nevertheless, our results highlight the importance of screening for depression and anxiety symptoms and assessing patients' subjective memory complaints as part of a neuropsychological evaluation as each of these factors tap into a different aspect of the patient functioning.

Statistical learning in epilepsy: Behavioral, anatomical, and causal mechanisms in the human brain

Statistical learning, the fundamental cognitive ability of humans to extract regularities across experiences over time, engages the medial temporal lobe in the healthy brain. This leads to the hypothesis that statistical learning may be impaired in epilepsy patients, and that this impairment could contribute to their varied memory deficits. In turn, epilepsy patients provide a platform to advance basic understanding of statistical learning by helping to evaluate the necessity of medial temporal lobe circuitry through disease and causal perturbations. We implemented behavioral testing, volumetric analysis of the medial temporal lobe substructures, and direct electrical brain stimulation to examine statistical learning across a cohort of 61 epilepsy patients and 28 healthy controls. Behavioral performance in a statistical learning task was negatively associated with seizure frequency, irrespective of where seizures originated in the brain. The volume of hippocampal subfields CA1 and CA2/3 correlated with statistical learning performance, suggesting a more specific role of the hippocampus. Indeed, transient direct electrical stimulation of the hippocampus disrupted statistical learning. Furthermore, the relationship between statistical learning and seizure frequency was selective: behavioral performance in an episodic memory task was impacted by structural lesions in the medial temporal lobe and by antiseizure medications, but not by seizure frequency. Overall, these results suggest that statistical learning may be hippocampally dependent and that this task could serve as a clinically useful behavioral assay of seizure frequency distinct from existing neuropsychological tests. Simple and short statistical learning tasks may thus provide patient-centered endpoints for evaluating the efficacy of novel treatments in epilepsy.

Recall and Self-Relevance of Emotional Words Predict Subjective Self-Evaluation of Cognition in Patients with MTLE with or without Depressive Symptoms

We examined whether word processing is associated with subjective self-evaluation of cognition in patients with mesial temporal lobe epilepsy (MTLE) as a function of their depressive symptoms. MTLE patients with (MTLE +d, N = 28) or without (MTLE -d, N = 11) depression were compared to pair-matched healthy control participants on free recall and self-relevance ratings of emotionally valenced words. Correlation and hierarchical analyses were conducted to investigate whether the subjective self-evaluation of cognition in MTLE patients is predicted by the negative emotional bias reflected in task performance. MTLE +d patients endorsed as self-relevant fewer positive words and more negative words than the MTLE -d patients and healthy participants. They also self-evaluated their cognition poorer than the MTLE -d patients. Analyses indicated that recall and self-endorsement of emotional words predicted both self-evaluation of cognition as well as epilepsy duration. Our findings indicate that negative self-relevance emotional bias is observed in MTLE patients and is predictive of subjective self-evaluation of cognition. Application of brief behavioral tasks probing emotional functions could be valuable for clinical research and practice in the patients with MTLE.

Visuospatial/executive abilities and mood affect the reliability of a subjective memory complaints measure

BACKGROUND

Inconsistent results are reported so far in the literature on the relationship between subjective memory complaints (SMC) and objective memory performance. Mixed findings triggered the need to investigate whether other potential mediating variables, such as mood and non-memory domains, affect the relationship between SMC and memory performance.

AIMS

The present study aimed to contribute in clarifying the relation between subjective and objective memory considering the potential role of mood and visuospatial/executive functions.

METHODS

Six hundred and sixty Italian community-dwelling adults (52-91 years old) were enrolled. Italian version of Montreal Cognitive Assessment Test (MoCA), Geriatric Depression Scale and Subjective Memory Complaints Questionnaire (SMCQ) were administered. Four subsamples were composed according to the following criteria: (a) participants with high visuospatial/executive function (VSE) score at MoCA and high mood; (b) participants with high VSE score and low mood; (c) participants with low VSE score and high mood and; (d) participants with low VSE score and low mood.

RESULTS

Preliminarily, two confirmatory factor analysis have set the one-factor structure of SMCQ as the best fitting model. Diagnostic accuracy of the SMCQ in discriminating high and low memory score was assessed. ROC analyses confirmed that a low score in executive tasks was associated with poor reliability of the SMCQ. On the contrary, well-preserved executive functions and high mood levels ensured a good reliability of SMCQ in detecting memory problems.

DISCUSSION AND CONCLUSIONS

Although mood is a key mediator in the relationship between subjective and objective memory, preserving executive functions is essential for ensuring the accuracy of memory self-appraisal in adulthood and elderly.

Sex differences in self-regulation in early, middle and late adolescence: A large-scale cross-sectional study

This large-scale cross-sectional study had the aim to investigate whether adolescent males and females differ in self-perceived self-regulation. The large sample size allowed us to investigate sex differences in three age-groups of young (n = 161), middle (n = 133) and late (n = 159) adolescents. Self-regulation was evaluated with a self-report questionnaire, the Amsterdam Executive Functioning Inventory (AEFI). This questionnaire gives a proxi for three executive functions that are important for proper self-regulation: (1) self-control & self-monitoring, (2) attention, and (3) planning & initiative taking. Results revealed clear sex differences in the self-regulation as perceived by mid-adolescents (i.e., 13-16 years). In this age period, females evaluated their attention higher than males, and they reported higher levels of self-control & self-monitoring. Our findings offer important new insights with respect to the decision making, academic achievements and behaviour of 13-16-year olds. Self-regulation is known to have a central role in academic achievement and in behavioural organisation. The sex differences in self-regulation in mid-adolescence may therefore explain part of the difference which males and females in this age-group exhibit in academic achievements and behavioural organisations. The results imply that self-regulation may be a relevant intervention target: rather than focussing on changing behaviour, interventions may focus more on self-insights and thereby changing the adolescent's perceptions about their behaviour. Increased self-insight may have the potency to actually change behaviour, which might be an interesting target for future investigation.

Contribution of autobiographic memory impairment to subjective memory complaints in focal epilepsy

"My memory is terrible!" is a common refrain among people with epilepsy, but such complaints are not reliably linked to poor performances on standard tests of memory. Negative affect like depression and anxiety are the most robust predictor of these complaints; however, neither do they entirely account for the phenomenon. The contribution of autobiographic memory impairment to subjective memory complaints in focal epilepsy has not been well-explored despite autobiographic memory impairments being common in patients with epilepsy, and the face validity of relating day-to-day memory failings to such a personally relevant form of memory. The current study sought to clarify whether autobiographic memory dysfunction contributes to subjective complaints in epilepsy, above and beyond negative affect, objective memory impairment, and epileptological factors in a large sample of patients with drug-resistant focal epilepsy relative to healthy controls (N = 135). Patients were stratified into groups with mesial temporal (MT; n = 40) versus nonmesial temporal (NMT; n = 46) foci. Compared to controls (n = 46), both patient groups reported more bitter subjective memory complaints (p < 0.001, large effect size), demonstrated poorer episodic (p = 0.001, large effect size) and semantic autobiographical recall (p = 0.004, medium effect size), and had higher levels of depressive symptomatology (p = 0.011, medium effect size), and trait neuroticism (p = 0.015, medium effect size). Contrary to expectations, multiple regression analyses revealed that autobiographic memory function was not an independent predictor of subjective memory complaints in either group with epilepsy. In people with epilepsy with MT foci, objective verbal memory dysfunction, neuroticism, and female gender predicted memory complaints (R² = 0.70, p = 0.015), whereas only neuroticism predicted memory complaints in people with epilepsy with NMT foci (R² = 0.21, p = 0.001). Although patients' poor recall of their autobiographical memories did not contribute to their concerns about their day-to-day memory function, the findings indicate that the location of the epileptogenic focus can provide clues as to the underlying contributors to subjective memory complaints in focal epilepsy. Important clinical implications to stem from these findings include the need for clinicians to adopt a patient-tailored, multifactorial lens when managing memory complaints in people with epilepsy, taking into account both psychological and cognitive factors.

Is the computerized assessment of psychomotor speed more sensitive to cognitive effects of antiepileptic pharmacotherapy than tests with a focus on higher-order cognitive processing? Implications for the choice of sensitive test parameters

The study evaluated whether it is psychomotor speed or higher-order cognitive processing which is primarily affected by antiepileptic drug (AED) treatment in epilepsy and whether computerized testing versus paper-pencil testing of executive functions is more sensitive. In this retrospective observational study, 55 patients with epilepsy underwent NeuroCog FX^Ⓡ, a computerized battery assessing "psychomotor speed/alertness" and "cognitive processing" via 8 tasks, and EpiTrack^Ⓡ, a paper-pencil screening of "executive functions and working memory" based on 6 subtests. Test performance was related to the number of drugs and the Defined Daily Dose and the presence/absence of AEDs with known adverse psychotropic effects. EpiTrack^Ⓡ performance correlated with "cognitive processing" of the NeuroCog FX^Ⓡ but not with "psychomotor speed/alertness". Significant correlations with drug load were mainly yielded for EpiTrack^Ⓡ (number of AEDs: r = -0.551, total DDD: r = -0.452) and "cognitive processing" (number of AEDs: r = -0.433, total DDD: r = -0.415). "Psychomotor speed/alertness" was less related to drug load (number of AEDs: r = -0.285, total DDD: r = -0.232). Statistical control for "psychomotor speed/alertness" hardly changed the correlations of EpiTrack^Ⓡ or "cognitive processing" with drug load indices. AEDs with known adverse profiles negatively affected EpiTrack^Ⓡ and the "cognitive processing" but not the "psychomotor speed/alertness" domain of the computerized test. The results demonstrate that it is less basal psychomotor speed than higher-order cognitive processing which is negatively affected by antiepileptic pharmacotherapy. The results question the value of (computer-)tests with a major emphasis on psychomotor speed and alertness for cognitive drug monitoring.

Cognitive assessment in an epilepsy clinic using the AD8 questionnaire

OBJECTIVE

This study examined cognitive function in patients with epilepsy using the AD8 screening questionnaire to assess the frequency of, and factors associated with, cognitive impairment in these patients.

METHOD

The AD8 screening questionnaire for cognitive impairment was administered to one hundred consecutive patients diagnosed with epilepsy who attended a dedicated epilepsy clinic based in a tertiary care neuroscience center. Where possible, accompanying informants also completed AD8 on behalf of the patient.

RESULTS

Forty-eight percent of patients in this cohort scored above the AD8 cutoff (higher scores are considered worse) for cognitive impairment. Categorizing patient groups by AD8 score showed no difference (null hypothesis not rejected) in patient age, new or follow-up appointment, epilepsy type (partial/generalized), or treatment (monotherapy/polytherapy), but a significant difference (null hypothesis rejected) was found for disee duration, with those scoring above the AD8 cutoff having a significantly longer disease duration. There was no correlation between AD8 scores and patient age but a weak positive correlation with disease duration. AD8 questionnaires completed by informants showed a similar frequency of cognitive impairment (54%), and patient:informant AD8 scores showed substantial agreement beyond chance.

CONCLUSIONS

AD8 is acceptable to patients with epilepsy and their informants for the assessment of cognitive function. In this dedicated epilepsy clinic, its use suggested a high frequency of cognitive impairment in both self-rating and informant assessments. A less sensitive, more specific cognitive screening instrument (CSI) might be more desirable in this population. Duration of epilepsy or some factor related to it may contribute to cognitive symptoms.