Higher IQ in juvenile myoclonic epilepsy: Dodging cognitive obstacles and "masking" impairments

Latent cognitive phenotypes in juvenile myoclonic epilepsy: Clinical, sociodemographic, and neuroimaging associations

OBJECTIVE

Application of cluster analytic procedures has advanced understanding of the cognitive heterogeneity inherent in diverse epilepsy syndromes and the associated clinical and neuroimaging features. Application of this unsupervised machine learning approach to the neuropsychological performance of persons with juvenile myoclonic epilepsy (JME) has yet to be attempted, which is the intent of this investigation.

METHODS

A total of 77 JME participants, 19 unaffected siblings, and 44 unrelated controls, 12 to 25 years of age, were administered a comprehensive neuropsychological battery (intelligence, language, memory, executive function, and processing speed), which was subjected to factor analysis followed by K-means clustering of the resultant factor scores. Identified cognitive phenotypes were characterized and related to clinical, family, sociodemographic, and cortical and subcortical imaging features.

RESULTS

Factor analysis revealed three underlying cognitive dimensions (general ability, speed/response inhibition, and learning/memory), with JME participants performing worse than unrelated controls across all factor scores, and unaffected siblings performing worse than unrelated controls on the general mental ability and learning/memory factors, with no JME vs sibling differences. K-means clustering of the factor scores revealed three latent groups including above average (31.4% of participants), average (52.1%), and abnormal performance (16.4%). Participant groups differed in their distributions across the latent groups (p < 0.001), with 23% JME, 22% siblings, and 2% unrelated controls in the abnormal performance group; and 18% JME, 21% siblings, and 59% unrelated controls in the above average group. Clinical epilepsy variables were unassociated with cluster membership, whereas family factors (lower parental education) and abnormally increased thickness and/or volume in the frontal, parietal, and temporal-occipital regions were associated with the abnormal cognition group.

SIGNIFICANCE

Distinct cognitive phenotypes characterize the spectrum of neuropsychological performance of patients with JME for which there is familial (sibling) aggregation. Phenotypic membership was associated with parental (education) and imaging characteristics (increased cortical thickness and volume) but not basic clinical seizure features.

The relevance of Spearman's g for epilepsy

Whilst the concept of a general mental factor known as 'g' has been of longstanding interest, for unknown reasons, it has never been interrogated in epilepsy despite the 100+ year empirical history of the neuropsychology of epilepsy. This investigation seeks to identify g within a comprehensive neuropsychological data set and compare participants with temporal lobe epilepsy to controls, characterize the discriminatory power of g compared with domain-specific cognitive metrics, explore the association of g with clinical epilepsy and sociodemographic variables and identify the structural and network properties associated with g in epilepsy. Participants included 110 temporal lobe epilepsy patients and 79 healthy controls between the ages of 19 and 60. Participants underwent neuropsychological assessment, clinical interview and structural and functional imaging. Cognitive data were subjected to factor analysis to identify g and compare the group of patients with control participants. The relative power of g compared with domain-specific tests was interrogated, clinical and sociodemographic variables were examined for their relationship with g, and structural and functional images were assessed using traditional regional volumetrics, cortical surface features and network analytics. Findings indicate (i) significantly (P < 0.005) lower g in patients compared with controls; (ii) g is at least as powerful as individual cognitive domain-specific metrics and other analytic approaches to discriminating patients from control participants; (iii) lower g was associated with earlier age of onset and medication use, greater number of antiseizure medications and longer epilepsy duration (Ps < 0.04); and lower parental and personal education and greater neighbourhood deprivation (Ps < 0.012); and (iv) amongst patients, lower g was linked to decreased total intracranial volume (P = 0.019), age and intracranial volume adjusted total tissue volume (P = 0.019) and age and intracranial volume adjusted total corpus callosum volume (P = 0.012)-particularly posterior, mid-posterior and anterior (Ps < 0.022) regions. Cortical vertex analyses showed lower g to be associated specifically with decreased gyrification in bilateral medial orbitofrontal regions. Network analysis of resting-state data with focus on the participation coefficient showed g to be associated with the superior parietal network. Spearman's g is reduced in patients, has considerable discriminatory power compared with domain-specific metrics and is linked to a multiplex of factors related to brain (size, connectivity and frontoparietal networks), environment (familial and personal education and neighbourhood disadvantage) and disease (epilepsy onset, treatment and duration). Greater attention to contemporary models of human cognition is warranted in order to advance the neuropsychology of epilepsy.

Outpatient visit behavior in patients with epilepsy: Generalized Epilepsy is more frequently non-attendance than Focal Epilepsy

BACKGROUND

Patients with epilepsy (PWE), especially those with Idiopathic Epilepsy (GE), are at a high risk of disadvantage caused by non-adherence. It has been suggested that medical visit behavior may be a surrogate indicator of medication adherence. We hypothesized that patients with IGE would adhere poorly to visits.

METHODS

This was a retrospective study of PWE who visited the Department of Psychiatry and Neurology at Hokkaido University Hospital between January 2017 and December 2019. Demographic and clinical information on PWE were extracted from medical records and visit data from the medical information system. Non-attendance of outpatient appointments was defined as "not showing up for the day of an appointment without prior notice." Mixed-effects logistic regression analysis was conducted with non-attendance as the objective variable.

RESULTS

Of the 9151 total appointments, 413 were non-attendances, with an overall non-attendance rate of 4.5%. IGE was a more frequent non-attendance than Focal Epilepsy (FE) (odds ratio (OR) 1.94; 95% confidence interval (CI) 1.17-3.21; p = 0.010). History of public assistance receipt was associated with higher non-attendance (OR 2.04; 95% CI 1.22-3.43; p = 0.007), while higher education (OR 0.64; 95% CI 0.43-0.93; p = 0.021) and farther distance to a hospital (OR 0.33; 95% CI 0.13-0.88; p = 0.022), and higher frequency of visits (OR 0.18; 95% CI 0.04-0.86; p = 0.031) were associated with fewer non-attendances. In a subgroup analysis of patients with GE, women were associated with fewer non-attendance (OR 0.31; 95% CI 0.14-0.72; p = 0.006).

CONCLUSIONS

GE was more frequent in the non-attendance group than in the FE group. Among patients with GE, females were found to have non-attendance less frequently; however, there was no clear difference in the odds of non-attendance between Juvenile Myoclonic Epilepsy (JME) and IGE other than JME.

Understanding frontal lobe function in epilepsy: Juvenile myoclonic epilepsy vs. frontal lobe epilepsy

AIM

To compare neuropsychological function in juvenile myoclonic epilepsy (JME) and frontal lobe epilepsy (FLE) since frontal circuitry is involved in both conditions. By drawing on previously theory-guided hypotheses and findings, a particular emphasis is placed on the way different cognitive-pathophysiological mechanisms act upon to produce frontal dysfunction in JME (frontal-executive and attention-related problems: vigilance, reaction times, processing speed, and response inhibition) and in FLE (reflecting the coproduct of the functional deficit zone), respectively.

METHODS

A total of 16 patients with JME, 34 patients with FLE, and 48 normal controls, all matched for age and education, were administered a comprehensive battery of tests to assess frontal-executive functions, as well as attention, memory, and learning domains. Participants did not take medications other than antiepileptics or have a psychiatric history.

RESULTS

Patients with FLE overall showed worse neuropsychological performance compared to both JME and HCs. With respect to JME, patients with FLE did significantly worse in measures of verbal and nonverbal executive function, short-term-, and long-term- auditory-verbal memory and learning, immediate and delayed episodic recall, visual attention and motor function, visuo-motor coordination and psychomotor speed, speed of visual information processing, and vocabulary. Patients with JME performed significantly worse compared to FLE only in associative semantic processing, while the former outperformed all groups in vocabulary, visuomotor coordination, and psychomotor speed.

CONCLUSION

We suggest that selective impairments of visual- and mostly auditory-speed of information processing, vigilance, and response inhibition may represent a salient neuropsychological feature in JME. These findings suggest the existence of an aberrantly working executive-attention system, secondary to pathological reticulo-thalamo-cortical dynamics. Contrariwise, cortically (frontal and extra-frontal) and subcortically induced malfunction in FLE is determined by the functional deficit zone i.e., the ensemble of cortical and subcortical areas that are functionally abnormal between seizures.

Neurobehavioural comorbidities of epilepsy: towards a network-based precision taxonomy

Cognitive and behavioural comorbidities are prevalent in childhood and adult epilepsies and impose a substantial human and economic burden. Over the past century, the classic approach to understanding the aetiology and course of these comorbidities has been through the prism of the medical taxonomy of epilepsy, including its causes, course, characteristics and syndromes. Although this 'lesion model' has long served as the organizing paradigm for the field, substantial challenges to this model have accumulated from diverse sources, including neuroimaging, neuropathology, neuropsychology and network science. Advances in patient stratification and phenotyping point towards a new taxonomy for the cognitive and behavioural comorbidities of epilepsy, which reflects the heterogeneity of their clinical presentation and raises the possibility of a precision medicine approach. As we discuss in this Review, these advances are informing the development of a revised aetiological paradigm that incorporates sophisticated neurobiological measures, genomics, comorbid disease, diversity and adversity, and resilience factors. We describe modifiable risk factors that could guide early identification, treatment and, ultimately, prevention of cognitive and broader neurobehavioural comorbidities in epilepsy and propose a road map to guide future research.

The burden of disease of idiopathic/genetic generalized epilepsy - A nationwide online survey

The aim of the study was to assess the self-reported burden of disease in people with idiopathic/genetic generalized epilepsy and risk factors associated with high disease burden. We performed a nationwide online survey on epilepsy characteristics/treatment, quality of life/daily living followed by Standardized Assessment of Personality-Abbreviated Scale, Major Depression Inventory, Barratt Impulsiveness Scale (brief) and the brief Epilepsy Anxiety Survey Instrument. The survey was sent to 275 representative patients with IGE ('Funen cohort') and later publicly distributed via the Danish Epilepsy Association. The characteristics of the responders of the 'Funen cohort' (n = 119) did not differ from non-responders and previously assessed data. Out of 753 persons accessing the public survey, 167 had probable IGE. As compared to the 'Funen cohort', patients from the public survey reported similar age, time since last seizure, years with disease, seizure types, and IGE syndromes but more current and previously tried anti-seizure medications (ASMs). In both cohorts, patients had higher scores for depression, impulsivity, and personality disorders as compared to Danish normal values irrespective of seizure control or medication. Higher depression and anxiety scores but neither impulsivity nor personality disorders were associated with ongoing seizures. Overall health condition was estimated as bad by 28%. In the last four weeks, 20.4% reported limitations of activities of daily living due to epilepsy; 27.8% felt fed up because of their epilepsy. Patients with high subjective disease burden had more current ASMs, shorter time since last seizure and increased scores for depression, anxiety, impulsivity, and personality disorders. In conclusion, having IGE was associated with higher scores for impulsivity, depression, and personality disorders irrespective of seizure control and current treatment. High subjective disease burden was common and associated with ongoing seizures, absence/myoclonic seizures and high scores for impulsivity, depression, anxiety, and personality disorders.

The impact of processing speed on cognition in temporal lobe epilepsy

PURPOSE

To characterize the impact of slowed processing speed on the efficiency of broader cognitive function in temporal lobe epilepsy (TLE).

METHODS

Participants included 100 patients with TLE and 89 healthy controls (mean ages 36.8 and 33.6, respectively) administered a neuropsychological battery consisting of 15 cognitive metrics. Confirmatory factor analysis using structural equation modeling (SEM) latent variable modeling demonstrated a cognitive structure representing the domains of verbal intelligence, immediate memory, delayed memory, executive function, working memory, and processing speed. Furthermore, the latent variable measurement model determined the direct and indirect relationships of verbal intelligence and processing speed with immediate memory, delayed memory, executive function, and working memory.

RESULTS

Following SEM of hypothesized structural models, the results demonstrated that, among controls, intelligence had a direct and unmediated (by processing speed) relationship with all identified cognitive domains. In contrast, among participants with TLE, processing speed mediated the relationship between verbal intelligence and performance across all cognitive domains.

CONCLUSION

Slowing of cognitive/psychomotor processing speed appears to play a critical mediating role in the broader cognitive status of participants with TLE and may serve as a target through which to attempt to exert a broad positive impact on neuropsychological status.

Social outcome and psychiatric comorbidity of generalized epilepsies - A case-control study

OBJECTIVE

To investigate social outcome and psychiatric comorbidity of patients with idiopathic/genetic generalized epilepsies (IGEs) and its subtypes (epilepsy with generalized tonic-clonic seizures alone [EGTCS], juvenile absence epilepsy [JAE], and juvenile myoclonic epilepsy [JME]).

METHODS

A cohort of 402 adult patients with IGE from the Danish island Funen was matched with 4020 randomly selected geography-, age-, and sex-matched controls via the Danish Civil Registration System. Based on register data, we compared social status measured by cohabitant status, educational attainment, income, affiliation to labor market, and psychiatric comorbidity.

RESULTS

As compared to controls, patients with IGE had similar cohabitant status but fewer children (no children: 59.0% vs 50.9%), and lower educational level (primary school only: 46.0% vs 37.3%), employment rate (outside of workforce: 56.7% vs 46.5%), and income (low income: 32.6% vs 24.9%) (P < 0.001 for all comparisons). Having IGE was associated with higher a proportion of psychiatric comorbidity (IGE, 22.6%; controls, 13.0%) (P < 0.001). Seizure-free patients did not differ from controls; patients with persistent seizures had lower incomes and employment rates. In the IGE subgroup analyses, JME was associated with worse social status in all parameters studied (eg, 65.9% of JME patients were outside the workforce vs 44.5% of matched controls; P < 0.001), whereas no adverse social status was identified in patients with EGTCS and JAE.

SIGNIFICANCE

Patients with IGE in general and JME in particular have poorer social status and more psychiatric comorbidity than matched population controls without epilepsy. Poor seizure control was associated with social status and may contribute to negative socioeconomic consequences associated with IGE.

Impulsiveness, personality traits and executive functioning in patients with juvenile myoclonic epilepsy

PURPOSE

To evaluate impulsiveness in adult patients with JME and its relationship with personality traits and executive functioning.

METHODS

Patients completed psychiatric evaluation (DSM IV), Barratt Impulsiveness Scale (BIS-11), Neo Revised Personality Inventory (NEO PI-R) and executive functioning evaluation comprising Controlled Oral Word Association (COWA), Digit Span, Trail Making Tests (TMT), Stroop Test (ST) and Wisconsin Card Sorting Test (WSCT). Healthy controls (63 % female, mean age 35.7 yrs. (±8.37)) were examined to allow calculation of z-scores.

RESULTS

50 patients (70 % female; mean age 32.5 yrs. (±9.2)) presented higher scores of Total (z=-0.37; p = 0.005) and Motor Impulsiveness (z=-0.79; p < 0.001) on BIS-11. Motor Impulsiveness was associated with higher rates of mild psychiatric disorders (depression and anxiety) (p = 0.035) and worse myoclonic seizure control (p = 0.007). NEO PI-R showed differences on Neuroticism (z=-0.60; p < 0.001), Openness (z = 0.38; p = 0.043), Agreeableness (z=-0.38; p = 0.033) and Conscientiousness (z=-0.53; p = 0.003). There were positive correlations between BIS-11 and Neuroticism with Total, Motor and Non-Planning Impulsiveness, on the other hand, Conscientiousness was negatively correlated with these as well as with Attentive Impulsiveness. Patients performance was worse than that of controls on COWA (z=-0.43; p = 0.009) and WCST's Total Number of Completed Categories (z=-2.08; p = 0.005), Trials Taken to Complete First Category (z=-1.56; p = 0.013), Percentage of Total Errors (z=-1.56; p < 0.001), Perseverative Errors (z=-0.73; p = 0.002), Non-Perseverative Errors (z=-1.05; p = 0.003) and Conceptual Level Responses (z=-1.52; p < 0.001). Non-Planning Impulsiveness correlated with Performance (ST and TMT).

CONCLUSION

Patients with JME present with impulsive behavior, personality features and executive dysfunction which are linked and may lead to lack of commitment in treatment and affect other aspects of life.

Cognitive Function in Genetic Generalized Epilepsies: Insights From Neuropsychology and Neuroimaging

Genetic generalized epilepsies (GGE), previously called idiopathic generalized epilepsies, constitute about 20% of all epilepsies, and include childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy, and epilepsy with generalized tonic-clonic seizures alone (CAE, JAE, JME, and GGE-GTCS, respectively). GGE are characterized by high heritability, likely underlain by polygenetic mechanisms, which may relate to atypical neurodevelopmental trajectories. Age of onset ranges from pre-school years, for CAE, to early adulthood for GGE-GTCS. Traditionally, GGE have been considered benign, a belief contrary to evidence from neuropsychology studies conducted over the last two decades. In JME, deficits in executive and social functioning are common findings and relate to impaired frontal lobe function. Studies using neuropsychological measures and cognitive imaging paradigms provide evidence for hyperconnectivity between prefrontal and motor cortices, aberrant fronto-thalamo-cortical connectivity, and reduced fronto-cortical and subcortical gray matter volumes, which are associated with altered cognitive performance. Recent research has also identified associations between abnormal hippocampal morphometry and fronto-temporal activation during episodic memory. Longitudinal studies on individuals with newly diagnosed JME have observed cortical dysmaturation, which is paralleled by delayed cognitive development compared to the patients' peers. Comorbidities and cognitive deficits observed in other GGE subtypes, such as visuo-spatial and language deficits in both CAE and JAE, have also been correlated with atypical neurodevelopment. Although it remains unclear whether cognitive impairment profiles differ amongst GGE subtypes, effects may become more pronounced with disease duration, particularly in absence epilepsies. Finally, there is substantial evidence that patients with JME and their unaffected siblings share patterns of cognitive deficits, which is indicative of an underlying genetic etiology (endophenotype), independent of seizures and anti-epileptic medication.

Working memory in pediatric frontal lobe epilepsy

Thirty-two children with frontal lobe epilepsy (FLE) were assessed using different working memory measures. In addition, parents and teachers completed the working memory scale of the Behavioral Rating Inventory of Executive Functioning (BRIEF) to assess the children's "daily life behavior." Results suggested minimal working memory deficits as assessed with performance-based measures. However, the BRIEF showed more working memory deficits suggesting that, on a daily life level, working memory problems seem to be associated with FLE. We discuss why the results of the performance-based measures are not consistent with results of the BRIEF.HighlightsParents as well as teachers report working memory dysfunction in daily life to the same extent.Performance based measures show minimal deficits of working memory.Correlation between working memory tasks and proxy measures are low.