Cross-cultural application of the International Classification of Cognitive Disorders in Epilepsy (IC-CoDE): Cognitive phenotypes in people with temporal lobe epilepsy in India.

OBJECTIVE: Efforts to understand the global variability in cognitive profiles in patients with epilepsy have been stymied by the lack of a standardized diagnostic system. This study examined the cross-cultural applicability of the International Classification of Cognitive Disorders in Epilepsy (IC-CoDE) in a cohort of patients with temporal lobe epilepsy (TLE) in India that was diverse in language, education, and cultural background. METHODS: A cohort of 548 adults with TLE from Mumbai completed a presurgical comprehensive neuropsychological evaluation. The IC-CoDE taxonomy was applied to derive cognitive phenotypes in the sample. Analyses of variance were conducted to examine differences in demographic and clinical characteristics across the phenotypes, and chi-squared tests were used to determine whether the phenotype distribution differed between the Mumbai sample and published data from a multicenter US sample. RESULTS: Using the IC-CoDE criteria, 47% of our cohort showed an intact cognitive profile, 31% a single-domain impairment, 16% a bidomain impairment, and 6% a generalized impairment profile. The distribution of cognitive phenotypes was similar between the Indian and US cohorts for the intact and bidomain phenotypes, but differed for the single and generalized domains. There was a larger proportion of patients with single-domain impairment in the Indian cohort and a larger proportion with generalized impairment in the US cohort. Among patients with single-domain impairment, a greater proportion exhibited memory impairment in the Indian cohort, whereas a greater proportion showed language impairment in the US sample, likely reflecting differences in language administration procedures and sample characteristics including a higher rate of mesial temporal sclerosis in the Indian sample. SIGNIFICANCE: Our results demonstrate the applicability of IC-CoDE in a group of culturally and linguistically diverse patients from India. This approach enhances our understanding of cognitive variability across cultures and enables harmonized and inclusive research into the neuropsychological aspects of epilepsy.

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.

Individual- and community-level social determinants of health are associated with cognition in older adults with focal epilepsy.

OBJECTIVE: Epilepsy is associated with significant health disparities, including access to specialized care and adverse outcomes that have been associated with several social determinants of health (SDOH). We sought to examine the relationship between individual- and community-level SDOH and cognitive outcomes in older adults with epilepsy. MATERIALS AND METHODS: We collected clinical, SDOH, and neuropsychological data in 57 older adults with epilepsy. Individual-level SDOH included patient factors (quality of education, income, insurance, marital status) and early-life environmental factors (parental education and occupation, childhood employment). Neighborhood deprivation was measured with the Area Deprivation Index (ADI). Stepwise regressions were conducted to examine the independent contribution of individual-level SDOH to cognitive performance, and Spearman rho correlations were conducted to examine the relationship between ADI and cognitive performance. The SDOH profiles of patients who met the criteria for cognitive impairment were examined. RESULTS: After controlling for clinical variables, patient factors (public health insurance, poorer quality of education) and early-life environmental factors (lower mother's education, lower father's and mother's occupational complexity, history of childhood employment) were significant predictors of lower performance on measures of global cognition, verbal learning and memory, processing speed, and executive function. Higher ADI values (greater disadvantage) were associated with lower scores on global cognitive measures, verbal learning and memory, and executive function. Patients who met criteria for cognitive impairment had, on average, a greater number of adverse SDOH, including lower household incomes and father's education, and higher ADI values compared to those who were cognitively intact. CONCLUSION: We provide new evidence of the role of individual- and community-level SDOH on cognitive outcomes in older adults with epilepsy. This emerging literature highlights the need to examine SDOH beyond epilepsy-related clinical factors. These data could inform the development of interventions focused on increasing access to epilepsy care, education, and resources and promoting brain and cognitive health within the most at-risk communities.

Longitudinal normative standards for cognitive tests and composites using harmonized data from two Wisconsin AD-risk-enriched cohorts.

INTRODUCTION: Published norms are typically cross-sectional and often are not sensitive to preclinical cognitive changes due to dementia. We developed and validated demographically adjusted cross-sectional and longitudinal normative standards using harmonized outcomes from two Alzheimer's disease (AD) risk-enriched cohorts. METHODS: Data from the Wisconsin Registry for Alzheimer's Prevention and the Wisconsin Alzheimer's Disease Research Center were combined. Quantile regression was used to develop unconditional (cross-sectional) and conditional (longitudinal) normative standards for 18 outcomes using data from cognitively unimpaired participants (N = 1390; mean follow-up = 9.25 years). Validity analyses (N = 2456) examined relationships between percentile scores (centiles), consensus-based cognitive statuses, and AD biomarker levels. RESULTS: Unconditional and conditional centiles were lower in those with consensus-based impairment or biomarker positivity. Similarly, quantitative biomarker levels were higher in those whose centiles suggested decline. DISCUSSION: This study presents normative standards for cognitive measures sensitive to pre-clinical changes. Future directions will investigate potential clinical applications of longitudinal normative standards. HIGHLIGHTS: Quantile regression was used to construct longitudinal norms for cognitive tests. Poorer percentile scores were related to concurrent diagnosis and Alzheimer's disease biomarkers. A ShinyApp was built to display test scores and norms and flag low performance.

Longitudinal plasma phosphorylated-tau217 and other related biomarkers in a non-demented Alzheimer's risk-enhanced sample.

INTRODUCTION: Understanding longitudinal change in key plasma biomarkers will aid in detecting presymptomatic Alzheimer's disease (AD). METHODS: Serial plasma samples from 424 Wisconsin Registry for Alzheimer's Prevention participants were analyzed for phosphorylated-tau217 (p-tau217; ALZpath) and other AD biomarkers, to study longitudinal trajectories in relation to disease, health factors, and cognitive decline. Of the participants, 18.6% with known amyloid status were amyloid positive (A+); 97.2% were cognitively unimpaired (CU). RESULTS: In the CU, amyloid-negative (A-) subset, plasma p-tau217 levels increased modestly with age but were unaffected by body mass index and kidney function. In the whole sample, average p-tau217 change rates were higher in those who were A+ (e.g., simple slopes(se) for A+ and A- at age 60 were 0.232(0.028) and 0.038(0.013))). High baseline p-tau217 levels predicted faster preclinical cognitive decline. DISCUSSION: p-tau217 stands out among markers for its strong association with disease and cognitive decline, indicating its potential for early AD detection and monitoring progression. HIGHLIGHTS: Phosphorylated-tau217 (p-tau217) trajectories were significantly different in people who were known to be amyloid positive. Subtle age-related trajectories were seen for all the plasma markers in amyloid-negative cognitively unimpaired. Kidney function and body mass index were not associated with plasma p-tau217 trajectories. Higher plasma p-tau217 was associated with faster preclinical cognitive decline.

Unified topological inference for brain networks in temporal lobe epilepsy using the Wasserstein distance.

Persistent homology offers a powerful tool for extracting hidden topological signals from brain networks. It captures the evolution of topological structures across multiple scales, known as filtrations, thereby revealing topological features that persist over these scales. These features are summarized in persistence diagrams, and their dissimilarity is quantified using the Wasserstein distance. However, the Wasserstein distance does not follow a known distribution, posing challenges for the application of existing parametric statistical models. To tackle this issue, we introduce a unified topological inference framework centered on the Wasserstein distance. Our approach has no explicit model and distributional assumptions. The inference is performed in a completely data driven fashion. We apply this method to resting-state functional magnetic resonance images (rs-fMRI) of temporal lobe epilepsy patients collected from two different sites: the University of Wisconsin-Madison and the Medical College of Wisconsin. Importantly, our topological method is robust to variations due to sex and image acquisition, obviating the need to account for these variables as nuisance covariates. We successfully localize the brain regions that contribute the most to topological differences. A MATLAB package used for all analyses in this study is available at https://github.com/laplcebeltrami/PH-STAT.

The relationship between mood and anxiety and cognitive phenotypes in adults with pharmacoresistant temporal lobe epilepsy.

OBJECTIVE: Patients with temporal lobe epilepsy (TLE) are often at a high risk for cognitive and psychiatric comorbidities. Several cognitive phenotypes have been identified in TLE, but it is unclear how phenotypes relate to psychiatric comorbidities, such as anxiety and depression. This observational study investigated the relationship between cognitive phenotypes and psychiatric symptomatology in TLE. METHODS: A total of 826 adults (age = 40.3, 55% female) with pharmacoresistant TLE completed a neuropsychological evaluation that included at least two measures from five cognitive domains to derive International Classification of Cognitive Disorders in Epilepsy (IC-CoDE) cognitive phenotypes (i.e., intact, single-domain impairment, bi-domain impairment, generalized impairment). Participants also completed screening measures for depression and anxiety. Psychiatric history and medication data were extracted from electronic health records. Multivariable proportional odds logistic regression models examined the relationship between IC-CoDE phenotypes and psychiatric variables after controlling for relevant covariates. RESULTS: Patients with elevated depressive symptoms had a greater odds of demonstrating increasingly worse cognitive phenotypes than patients without significant depressive symptomatology (odds ratio [OR] = 1.123-1.993, all corrected p's < .05). Number of psychotropic (OR = 1.584, p < .05) and anti-seizure medications (OR = 1.507, p < .001), use of anti-seizure medications with mood-worsening effects (OR = 1.748, p = .005), and history of a psychiatric diagnosis (OR = 1.928, p < .05) also increased the odds of a more severe cognitive phenotype, while anxiety symptoms were unrelated. SIGNIFICANCE: This study demonstrates that psychiatric factors are not only associated with function in specific cognitive domains but also with the pattern and extent of deficits across cognitive domains. Results suggest that depressive symptoms and medications are strongly related to cognitive phenotype in adults with TLE and support the inclusion of these factors as diagnostic modifiers for cognitive phenotypes in future work. Longitudinal studies that incorporate neuroimaging findings are warranted to further our understanding of the complex relationships between cognition, mood, and seizures and to determine whether non-pharmacologic treatment of mood symptoms alters cognitive phenotype.

Establishing the cross-cultural applicability of a harmonized approach to cognitive diagnostics in epilepsy: Initial results of the International Classification of Cognitive Disorders in Epilepsy in a Spanish-speaking sample.

OBJECTIVE: This study was undertaken to evaluate the cross-cultural application of the International Classification of Cognitive Disorders in Epilepsy (IC-CoDE) to a cohort of Spanish-speaking patients with temporal lobe epilepsy (TLE) living in the United States. METHODS: Eighty-four Spanish-speaking patients with TLE completed neuropsychological measures of memory, language, executive function, visuospatial functioning, and attention/processing speed as part of the Neuropsychological Screening Battery for Hispanics. The contribution of demographic and clinical variables to cognitive performance was evaluated. A sensitivity analysis was conducted by examining the base rates of impairment across several impairment thresholds. The IC-CoDE taxonomy was then applied, and the base rate of cognitive phenotypes for each cutoff was calculated. The distribution of phenotypes was compared to the published IC-CoDE taxonomy data, which utilized a large, multicenter cohort of English-speaking patients with TLE. RESULTS: Across the different impairment cutoffs, memory was the most impaired cognitive domain, with impairments in list learning ranging from 50% to 78%. Application of the IC-CoDE taxonomy utilizing a -1.5-SD cutoff revealed an intact cognitive profile in 47.6% of patients, single-domain impairment in 23.8% of patients, bidomain impairment in 14.3% of patients, and generalized impairment in 14.3% of the sample. This distribution was comparable to the phenotype distribution observed in the IC-CoDE validation sample. SIGNIFICANCE: We demonstrate a similar pattern and distribution of cognitive phenotypes in a Spanish-speaking epilepsy cohort compared to an English-speaking sample. This suggests stability in the underlying phenotypes associated with TLE and applicability of the IC-CoDE for guiding cognitive diagnostics in epilepsy research that can be applied to culturally and linguistically diverse samples.

Disadvantage and neurocognitive comorbidities in childhood idiopathic epilepsies.

OBJECTIVE: This study was undertaken to characterize the relationship between neighborhood disadvantage and cognitive function as well as clinical, sociodemographic, and family factors in children with new onset idiopathic epilepsy and healthy controls. METHODS: Research participants were 288 children aged 8-18 years with recent onset epilepsy (CWE; n = 182; mean age = 12.2 ± 3.2 years), healthy first-degree cousin controls (HC; n = 106; mean age = 12.5 ± 3.0), and one biological or adopted parent per child (n = 279). All participants were administered a comprehensive neuropsychological battery (reasoning, language, memory, executive function, motor function, and academic achievement). Family residential addresses were entered into the Neighborhood Atlas to determine each family's Area Deprivation Index (ADI), a metric used to quantify income, education, employment, and housing quality. A combination of parametric and nonparametric (χ2 ) tests examined the effect of ADI by group (epilepsy and controls) across cognitive, academic, clinical, and family factors. RESULTS: Disadvantage (ADI) was equally distributed between groups (p = .63). For CWE, high disadvantage was associated with lower overall intellectual quotient (IQ; p = .04), visual naming/expressive language (p = .03), phonemic (letter) fluency (p < .01), passive inattention (omission errors; p = .03), delayed verbal recall (p = .04), and dominant fine motor dexterity and speed (p < .01). Cognitive status of the HC group did not differ by level of disadvantage (p = .40). CWE exhibited greater academic difficulties in comparison to HC (p < .001), which were exacerbated by disadvantage in CWE (p = .02) but not HC (p < .05). High disadvantage was associated with a threefold risk for academic challenges prior to epilepsy onset (odds ratio = 3.31, p = .024). SIGNIFICANCE: Socioeconomic hardship (increased neighborhood disadvantage) exerts a significant adverse impact on the cognitive and academic status of youth with new and recent onset epilepsies, an impact that needs to be incorporated into etiological models of the neurobehavioral comorbidities of epilepsy.

Neighborhood disadvantage and intellectual development in youth with epilepsy.

RATIONALE: Recent cross-sectional investigations have demonstrated an adverse impact of socioeconomic disadvantage on cognition and behavior in youth and adults with epilepsy. The goal of this study is to investigate the impact of disadvantage on prospective intellectual development in youth with epilepsy. METHOD: Participants were youth, aged 8-18 years, with recent onset epilepsy (n = 182) and healthy first-degree cousin controls (n = 106). The Wechsler Abbreviated Scale of Intelligence (WASI) was administered at baseline and 2 years later. The Neighborhood Atlas identified each family's Area Deprivation Index via state deciles and national percentiles. WASI data were analyzed by mixed group by time ANOVAs followed by regression analysis to identify other baseline predictors of time 2 outcomes. RESULTS: Youth with epilepsy demonstrated significant interactions between group and time for both verbal (F = 4.02, df = 1,215, p =.05) and nonverbal (F = 4.57, df = 1,215, p =.04) reasoning, demonstrating that disadvantage was associated with slower cognitive development compared to advantaged youth with epilepsy. Similar interactions were not observed for controls. CONCLUSIONS: In youth with new and recent onset epilepsies, neighborhood-level disadvantage is associated with a negative impact on the development of verbal and nonverbal reasoning skills.

Neighborhood disadvantage and health-related quality of life in pediatric epilepsy.

INTRODUCTION: While several demographic and epilepsy-specific characteristics are associated with diminished HRQoL in children and adolescents with epilepsy, prior investigations have failed to incorporate and address the influence of broader social contextual factors on functional outcomes. To address this gap, the purpose of the current study was to investigate the role of neighborhood disadvantage on HRQoL, including the extent to which familial and seizure-specific risk factors are impacted. METHODS: Data included parental ratings on the Quality of Life in Childhood Epilepsy (QOLCE) questionnaire for 135 children and adolescents with epilepsy, and the Area Deprivation Index (ADI) to measure neighborhood disadvantage. Bivariate correlations were conducted to identify significant associations with neighborhood disadvantage, followed by a three-stage hierarchical multiple regression to predict HRQoL. Follow-up binary logistic regressions were used to determine the risk conferred by neighborhood disadvantage on sociodemographic, seizure-specific, and HRQoL factors. RESULTS: Moderate associations between neighborhood disadvantage and familial factors, including parental psychiatric history and Medicaid insurance, were identified, while disadvantage and greater seizure frequency were marginally associated. Neighborhood disadvantage independently predicted HRQoL, and was the sole significant predictor of HRQoL when familial factors were incorporated. Children with epilepsy living in disadvantaged areas were four times more likely to have diminished HRQoL, five times more likely to live with a parent with a significant psychiatric history, and four times more likely to reside with a family receiving Medicaid insurance. CONCLUSIONS: These results highlight the importance of identifying high-risk groups, as the cumulative burden of social context, familial factors, and seizure-specific characteristics contribute to lower HRQoL in pediatric epilepsy which disproportionately affects patients from lower-resourced backgrounds. Potentially modifiable factors such as parental psychiatric status exist within the child's environment, emphasizing the importance of a whole-child approach to patient care. Further exploration of disadvantage in this population is needed to better understand these relationships over time.

Application of the International Classification of Cognitive Disorders in Epilepsy (IC-CoDE) to frontal lobe epilepsy using multicenter data.

RATIONALE: The International Classification of Cognitive Disorders in Epilepsy (IC-CoDE) was recently introduced as a consensus-based, empirically-driven taxonomy of cognitive disorders in epilepsy and has been effectively applied to patients with temporal lobe epilepsy (TLE). The purpose of this study was to apply the IC-CoDE to patients with frontal lobe epilepsy (FLE) using national multicenter data. METHODS: Neuropsychological data of 455 patients with FLE aged 16 years or older were available across four US-based sites. First, we examined test-specific impairment rates across sites using two impairment thresholds (1.0 and 1.5 standard deviations below the normative mean). Following the proposed IC-CoDE guidelines, patterns of domain impairment were determined based on commonly used tests within five cognitive domains (language, memory, executive functioning, attention/processing speed, and visuospatial ability) to construct phenotypes. Impairment rates and distributions across phenotypes were then compared with those found in patients with TLE for which the IC-CoDE classification was initially validated. RESULTS: The highest rates of impairment were found among tests of naming, verbal fluency, speeded sequencing and set-shifting, and complex figure copy. The following IC-CoDE phenotype distributions were observed using the two different threshold cutoffs: 23-40% cognitively intact, 24-29% single domain impairment, 13-20% bi-domain impairment, and 18-33% generalized impairment. Language was the most common single domain impairment (68% for both thresholds) followed by attention and processing speed (15-18%). Overall, patients with FLE reported higher rates of cognitive impairment compared with patients with TLE. CONCLUSIONS: These results demonstrate the applicability of the IC-CoDE to epilepsy syndromes outside of TLE. Findings indicated generally stable and reproducible phenotypes across multiple epilepsy centers in the U.S. with diverse sample characteristics and varied neuropsychological test batteries. Findings also highlight opportunities for further refinement of the IC-CoDE guidelines as the application expands.

Deficits in Behavioral and Neuronal Pattern Separation in Temporal Lobe Epilepsy.

In temporal lobe epilepsy, the ability of the dentate gyrus to limit excitatory cortical input to the hippocampus breaks down, leading to seizures. The dentate gyrus is also thought to help discriminate between similar memories by performing pattern separation, but whether epilepsy leads to a breakdown in this neural computation, and thus to mnemonic discrimination impairments, remains unknown. Here we show that temporal lobe epilepsy is characterized by behavioral deficits in mnemonic discrimination tasks, in both humans (females and males) and mice (C57Bl6 males, systemic low-dose kainate model). Using a recently developed assay in brain slices of the same epileptic mice, we reveal a decreased ability of the dentate gyrus to perform certain forms of pattern separation. This is because of a subset of granule cells with abnormal bursting that can develop independently of early EEG abnormalities. Overall, our results linking physiology, computation, and cognition in the same mice advance our understanding of episodic memory mechanisms and their dysfunction in epilepsy.SIGNIFICANCE STATEMENT People with temporal lobe epilepsy (TLE) often have learning and memory impairments, sometimes occurring earlier than the first seizure, but those symptoms and their biological underpinnings are poorly understood. We focused on the dentate gyrus, a brain region that is critical to avoid confusion between similar memories and is anatomically disorganized in TLE. We show that both humans and mice with TLE experience confusion between similar situations. This impairment coincides with a failure of the dentate gyrus to disambiguate similar input signals because of pathologic bursting in a subset of neurons. Our work bridges seizure-oriented and memory-oriented views of the dentate gyrus function, suggests a mechanism for cognitive symptoms in TLE, and supports a long-standing hypothesis of episodic memory theories.

Behavioral phenotypes of pediatric temporal lobe epilepsy.

OBJECTIVE: A broad spectrum of emotional-behavioral problems have been reported in pediatric temporal lobe epilepsy (TLE), but with considerable variability in their presence and nature of expression, which hampers precise identification and treatment. The present study aimed to empirically identify latent patterns or behavioral phenotypes and their correlates. METHODS: Data included parental ratings of emotional-behavioral status on the Behavior Assessment System for Children, 2nd Edition (BASC-2) of 81 children (mean age = 11.79, standard deviation [SD] = 3.93) with TLE. The nine clinical subscales were subjected to unsupervised machine learning to identify behavioral subgroups. To explore concurrent validity and the underlying composition of the identified clusters, we examined demographic factors, seizure characteristics, psychosocial factors, neuropsychological performance, psychiatric status, and health-related quality of life (HRQoL). RESULTS: Three behavioral phenotypes were identified, which included no behavioral concerns (Cluster 1, 43% of sample), externalizing problems (Cluster 2, 41% of sample), and internalizing problems (Cluster 3, 16% of sample). Behavioral phenotypes were characterized by important differences across clinical seizure variables, psychosocial/familial factors, everyday executive functioning, and HRQoL. Cluster 2 was associated with younger child age, lower maternal education, and higher rate of single-parent households. Cluster 3 was associated with older age at epilepsy onset and higher rates of hippocampal sclerosis and parental psychiatric history. Both Cluster 2 and 3 demonstrated elevated family stress. Concurrent validity was demonstrated through the association of psychiatric (i.e., rate of Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) disorders and psychotropic medication) and parent-rated HRQoL variables. SIGNIFICANCE: Youth with TLE present with three distinct behavioral phenotypes that correspond with important clinical and sociodemographic markers. The current findings demonstrate the variability of behavioral presentations in youth with TLE and provide a preliminary framework for screening and targeting intervention to enhance support for youth with TLE and their families.

Cognitive phenotypes in frontal lobe epilepsy.

OBJECTIVE: Neuropsychological profiles are heterogeneous both across and within epilepsy syndromes, but especially in frontal lobe epilepsy (FLE), which has complex semiology and epileptogenicity. This study aimed to characterize the cognitive heterogeneity within FLE by identifying cognitive phenotypes and determining their demographic and clinical characteristics. METHOD: One hundred and six patients (age 16-66; 44% female) with FLE completed comprehensive neuropsychological testing, including measures within five cognitive domains: language, attention, executive function, processing speed, and verbal/visual learning. Patients were categorized into one of four phenotypes based on the number of impaired domains. Patterns of domain impairment and clinical and demographic characteristics were examined across phenotypes. RESULTS: Twenty-five percent of patients met criteria for the Generalized Phenotype (impairment in at least four domains), 20% met criteria for the Tri-Domain Phenotype (impairment in three domains), 36% met criteria for the Domain-Specific Phenotype (impairment in one or two domains), and 19% met criteria for the Intact Phenotype (no impairment). Language was the most common domain-specific impairment, followed by attention, executive function, and processing speed. In contrast, learning was the least impacted cognitive domain. The Generalized Phenotype had fewer years of education compared to the Intact Phenotype, but otherwise, there was no differentiation between phenotypes in demographic and clinical variables. However, qualitative analysis suggested that the Generalized and Tri-Domain Phenotypes had a more widespread area of epileptogenicity, whereas the Intact Phenotype most frequently had seizures limited to the lateral frontal region. SIGNIFICANCE: This study identified four cognitive phenotypes in FLE that were largely indistinguishable in clinical and demographic features, aside from education and extent of epileptogenic zone. These findings enhance our appreciation of the cognitive heterogeneity within FLE and provide additional support for the development and use of cognitive taxonomies in epilepsy.

Diagnosing cognitive disorders in older adults with epilepsy.

OBJECTIVE: To characterize the nature and prevalence of cognitive disorders in older adults with temporal lobe epilepsy (TLE) and compare their cognitive profiles to patients with amnestic mild cognitive impairment (ie, aMCI). METHODS: Seventy-one older patients with TLE, 77 aMCI, and 69 normal aging controls (NACs), all 55-80 years of age, completed neuropsychological measures of memory, language, executive function, and processing speed. An actuarial neuropsychological method designed to diagnose MCI was applied to individual patients to identify older adults with TLE who met diagnostic criteria for MCI (TLE-MCI). A linear classifier was performed to evaluate how well the diagnostic criteria differentiated patients with TLE-MCI from aMCI. In TLE, the contribution of epilepsy-related and vascular risk factors to cognitive impairment was evaluated using multiple regression. RESULTS: Forty-three TLE patients (60%) met criteria for TLE-MCI, demonstrating marked deficits in both memory and language. When patients were analyzed according to age at seizure onset, 63% of those with an early onset (<50 years) versus 56% of those with late onset (≥ 50 years) met criteria for TLE-MCI. A classification model between TLE-MCI and aMCI correctly classified 81.1% (90.6% specificity, 61.3% sensitivity) of the cohort based on neuropsychological scores. Whereas TLE-MCI showed greater deficits in language relative to aMCI, patients with aMCI showed greater rapid forgetting on memory measures. Both epilepsy-related risk factors and the presence of leukoaraiosis on MRI contributed to impairment profiles in TLE-MCI. SIGNIFICANCE: Cognitive impairment is a common comorbidity in epilepsy and it presents in a substantial number of older adults with TLE. Although the underlying etiologies are unknown in many patients, the TLE-MCI phenotype may be secondary to an accumulation of epilepsy and vascular risk factors, signal the onset of a neurodegenerative disease, or represent a combination of factors.

The role of genetic polymorphisms in executive functioning performance in temporal lobe epilepsy.

OBJECTIVE: To explore the role of several genetic polymorphisms (APOE ε4, BDNF Met, and COMT Val) in executive functioning performance in patients with pharmacoresistant temporal lobe epilepsy (TLE). METHODS: Ninety-three adults (51 female, mean age = 39 years) with TLE completed executive functioning measures as part of a comprehensive preoperative neuropsychological evaluation, including Trail Making Test (Part B), Wisconsin Card Sorting Test (Conceptual Level Responses and Perseverative Errors), Color Word Interference from the Delis Kaplan Executive Function System, and measures of phonemic and semantic verbal fluency. Genotyping of the APOE, BDNF, and COMT genes was conducted using DNA extracted from peripheral blood or brain tissue (from epilepsy surgery). RESULTS: After adjustment for general cognitive ability, COMT Val carriers showed poorer performance on semantic verbal fluency and color word interference than non-carriers, and BDNF Met carriers showed poorer performance on phonemic verbal fluency than those without a Met allele. SIGNIFICANCE: Results suggest that COMT and BDNF polymorphisms are associated with performance on several EF measures in patients with TLE, including tasks assessing verbal fluency and response inhibition and account for up to 16% of the variance in test performance. The APOE polymorphism was not significantly associated with any of the executive function measures analyzed.

Regional and global resting-state functional MR connectivity in temporal lobe epilepsy: Results from the Epilepsy Connectome Project.

Temporal lobe epilepsy (TLE) has been conceptualized as focal disease with a discrete neurobiological focus and can respond well to targeted resection or ablation. In contrast, the neuro-cognitive deficits resulting from TLE can be widespread involving regions beyond the primary epileptic network. We hypothesize that this seemingly paradoxical findings can be explained by differences in connectivity between the primary epileptic region which is hyper-connected and its secondary influence on global connectome organization. This hypothesis is tested using regional and global graph theory metrics where we anticipate that regional mesial-temporal hyperconnectivity will be found and correlate with seizure frequency while global networks will be disorganized and be more closely associated with neuro-cognitive deficits. Resting-state fMRI was used to examine temporal lobe regional connectivity and global functional connectivity from 102 patients with TLE and 55 controls. Connectivity matrices were calculated for subcortical volumes and cortical parcellations. Graph theory metrics (global clustering coefficient (GCC), degree, closeness) were compared between groups and in relation to neuropsychological profiles and disease covariates using permutation testing and causal analysis. In TLE there was a decrease in GCC (p = 0.0345) associated with a worse neuropsychological profile (p = 0.0134). There was increased connectivity in the left hippocampus/amygdala (degree p = 0.0103, closeness p = 0.0104) and a decrease in connectivity in the right lateral temporal lobe (degree p = 0.0186, closeness p = 0.0122). A ratio between the hippocampus/amygdala and lateral temporal lobe-temporal lobe connectivity ratio (TLCR) revealed differences between TLE and controls for closeness (left p = 0.00149, right p = 0.0494) and for degree on left p = 0.00169; with trend on right p = 0.0567. Causal analysis suggested that "Epilepsy Activity" (seizure frequency, anti-seizure medications) was associated with increase in TLCR but not in GCC, while cognitive decline was associated with decreased GCC. These findings support the hypothesis that in TLE there is hyperconnectivity in the hippocampus/amygdala and hypoconnectivity in the lateral temporal lobe associated with "Epilepsy Activity." While, global connectome disorganization was associated with worse neuropsychological phenotype.

Verbal memory dysfunction is associated with alterations in brain transcriptome in dominant temporal lobe epilepsy.

OBJECTIVE: Memory dysfunction is prevalent in many neurological disorders and can have a significant negative impact on quality of life. The genetic contributions to memory impairment in epilepsy, particularly temporal lobe epilepsy (TLE), remain poorly understood. Here, we compare the brain transcriptome between TLE patients with and without verbal memory impairments to identify genes and signaling networks important for episodic memory. METHODS: Brain tissues were resected from 23 adults who underwent dominant temporal lobectomy for treatment of pharmacoresistant epilepsy. To control for potential effects of APOE on memory, only those homozygous for the APOE ε3 allele were included. A battery of memory tests was performed, and patients were stratified into two groups based on preoperative memory performance. The groups were well matched on demographic and disease-related variables. Total RNA-Seq and small RNA-Seq were performed on RNA extracted from the brain tissues. Pathway and integrative analyses were subsequently performed. RESULTS: We identified 1092 differentially expressed transcripts (DETs), with the majority (71%) being underexpressed in brain tissues from patients with impaired memory compared to those from patients with intact memory. Enrichment analysis revealed overrepresentation of genes in pathways pertaining to brain-related neurological dysfunction, including a subset associated with neurodegenerative diseases, memory, and cognition (APP, MAPT, PINK1). Despite including patients with identical APOE genotypes, we identify APOE as a differentially expressed gene associated with memory status. Small RNA-Seq identified four differentially expressed microRNAs (miRNAs) that were predicted to target a subset (22%) of all DETs. Integrative analysis showed that these miRNA-predicted DET targets impact brain-related pathways and biological processes also pertinent to memory and cognition. SIGNIFICANCE: TLE-associated memory status may be influenced by differences in gene expression profiles within the temporal lobe. Upstream processes influencing differential expression signatures, such as miRNAs, could serve as biomarkers and potential treatment targets for memory impairment in TLE.

Cognitive phenotypes in temporal lobe epilepsy utilizing data- and clinically driven approaches: Moving toward a new taxonomy.

OBJECTIVE: To identify cognitive phenotypes in temporal lobe epilepsy (TLE) and test their reproducibility in a large, multi-site cohort of patients using both data-driven and clinically driven approaches. METHOD: Four-hundred seven patients with TLE who underwent a comprehensive neuropsychological evaluation at one of four epilepsy centers were included. Scores on tests of verbal memory, naming, fluency, executive function, and psychomotor speed were converted into z-scores based on 151 healthy controls (HCs). For the data-driven method, cluster analysis (k-means) was used to determine the optimal number of clusters. For the clinically driven method, impairment was defined as >1.5 standard deviations below the mean of the HC, and patients were classified into groups based on the pattern of impairment. RESULTS: Cluster analysis revealed a three-cluster solution characterized by (a) generalized impairment (29%), (b) language and memory impairment (28%), and (c) no impairment (43%). Based on the clinical criteria, the same broad categories were identified, but with a different distribution: (a) generalized impairment (37%), (b) language and memory impairment (30%), and (c) no impairment (33%). There was a 82.6% concordance rate with good agreement (κ = .716) between the methods. Forty-eight patients classified as having a normal profile based on cluster analysis were classified as having generalized impairment (n = 16) or an isolated language/memory impairment (n = 32) based on the clinical criteria. Patients with generalized impairment had a longer disease duration and patients with no impairment had more years of education. However, patients demonstrating the classic TLE profile (ie, language and memory impairment) were not more likely to have an earlier age at onset or mesial temporal sclerosis. SIGNIFICANCE: We validate previous findings from single-site studies that have identified three unique cognitive phenotypes in TLE and offer a means of translating the patterns into a clinical diagnostic criteria, representing a novel taxonomy of neuropsychological status in TLE.