Attention and inhibitory control deficits in patients with genetic generalized epilepsy and psychogenic nonepileptic seizure

Neurocognitive performance in functional neurological disorder: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

Cognitive complaints are common in functional neurological disorder (FND), but it is unclear whether objective neurocognitive deficits are present. This systematic review summarized validated/standardized cognitive test performance in FND samples across cognitive domains.

METHODS

Embase, PsycInfo and MEDLINE were searched from inception to 15 May 2023, combining terms for FND and cognitive domains (e.g., attention, memory, executive functioning). Studies included a range of FND phenotypes (seizures, motor, cognitive disorder, mixed), compared to healthy or clinical controls. Risk of bias was assessed with the modified Newcastle-Ottawa Scale and a qualitative synthesis/narrative review of cognitive performance in FND was conducted. Test performance scores were extracted, and random effects meta-analyses were run where appropriate. This review was registered on PROSPERO, CRD42023423139.

RESULTS

Fifty-six studies including 2260 individuals with FND were eligible. Although evidence for some impairments emerged across domains of executive functioning, attention, memory and psychomotor/processing speed, this was inconsistent across studies and FND phenotypes. Common confounds included group differences in demographics, medication and intellectual functioning. Only 24% of studies objectively assessed performance validity. Meta-analyses revealed higher scores on tests of naming (g = 0.67, 95% confidence interval [CI] 0.50, 0.84) and long-term memory (g = 0.43, 95% CI 0.13, 0.74) in functional seizures versus epilepsy, but no significant differences in working (g = -0.08, 95% CI -0.44, 0.29) or immediate (g = 0.25, 95% CI -0.02, 0.53) memory and cognitive flexibility (g = -0.01, 95% CI -0.29, 0.28).

CONCLUSIONS

There is mixed evidence for objective cognitive deficits in FND. Future research should control for confounds, include tests of performance validity, and assess relationships between objective and subjective neurocognitive functioning.

Attentional Deficits and Absence Epilepsy: A Tale of 2 Interneuronopathies

Prefrontal PV Interneurons Facilitate Attention and Are Linked to Attentional Dysfunction in a Mouse Model of Absence Epilepsy Ferguson B, Glick C, Huguenard JR. Elife . 2023;12:e78349. doi:10.7554/eLife.78349 Absence seizures are characterized by brief periods of unconsciousness accompanied by lapses in motor function that can occur hundreds of times throughout the day. Outside of these frequent moments of unconsciousness, approximately a third of people living with the disorder experience treatment-resistant attention impairments. Convergent evidence suggests prefrontal cortex (PFC) dysfunction may underlie attention impairments in affected patients. To examine this, we use a combination of slice physiology, fiber photometry, electrocorticography (ECoG), optogenetics, and behavior in the Scn8a+/-mouse model of absence epilepsy. Attention function was measured using a novel visual attention task where a light cue that varied in duration predicted the location of a food reward. In Scn8a+/-mice, we find altered parvalbumin interneuron (PVIN) output in the medial PFC (mPFC) in vitro and PVIN hypoactivity along with reductions in gamma power during cue presentation in vivo. This was associated with poorer attention performance in Scn8a+/-mice that could be rescued by gamma-frequency optogenetic stimulation of PVINs. This highlights cue-related PVIN activity as an important mechanism for attention and suggests PVINs may represent a therapeutic target for cognitive comorbidities in absence epilepsy.

Objective and subjective neurocognitive functioning in functional motor symptoms and functional seizures: preliminary findings

INTRODUCTION

This study aimed to provide a preliminary assessment of objective and subjective neurocognitive functioning in individuals with functional motor symptoms (FMS) and/or functional seizures (FS). We tested the hypotheses that the FMS/FS group would display poorer objective attentional and executive functioning, altered social cognition, and reduced metacognitive accuracy.

METHOD

Individuals with FMS/FS (n = 16) and healthy controls (HCs, n = 17) completed an abbreviated CANTAB battery, and measures of intellectual functioning, subjective cognitive complaints, performance validity, and comorbid symptoms. Subjective performance ratings were obtained to assess local metacognitive accuracy.

RESULTS

The groups were comparable in age (p = 0.45), sex (p = 0.62), IQ (p = 0.57), and performance validity (p-values = 0.10-0.91). We observed no impairment on any CANTAB test in this FMS/FS sample compared to HCs, although the FMS/FS group displayed shorter reaction times on the Emotional Bias task (anger) (p = 0.01, np2 = 0.20). The groups did not differ in subjective performance ratings (p-values 0.15). Whilst CANTAB attentional set-shifting performance (total trials/errors) correlated with subjective performance ratings in HCs (p-values<0.005, rs = -0.85), these correlations were non-significant in the FMS/FS sample (p-values = 0.10-0.13, rs-values = -0.46-0.50). The FMS/FS group reported more daily cognitive complaints than HCs (p = 0.006, g = 0.92), which were associated with subjective performance ratings on CANTAB sustained attention (p = 0.001, rs = -0.74) and working memory tests (p < 0.001, rs = -0.75), and with depression (p = 0.003, rs = 0.70), and somatoform (p = 0.003, rs = 0.70) and psychological dissociation (p-values<0.005, rs-values = 0.67-0.85).

CONCLUSIONS

These results suggest a discordance between objective and subjective neurocognitive functioning in this FMS/FS sample, reflecting intact test performance alongside poorer subjective cognitive functioning. Further investigation of neurocognitive functioning in FND subgroups is necessary.

Comparing neuropsychological functioning in Turkish patients with right and left temporal lobe epilepsy

We compared neuropsychiatric evaluations in temporal lobe epilepsy according to the lateralized hemisphere. Forty-one (68.3%) left-sided temporal lobe epilepsy (LTLE) were compared to 19 right-sided temporal lobe epilepsy (RTLE) (31.7%) (p < 0.001). RTLE mean age was 37 (22-46) years, and LTLE mean age 38 was (30-42). RTLE disease duration was 10 (6-20) years, and LTLE was 22 (10-33) (p < 0.013). Gender (man/woman) for RTLE was 7/12, and for LTLE was 18/23. LTLE scored poorer on the Wechsler Memory Scale (WMS)-III's Mental Control Months-error, WMS-V's "Forward Number Range" and "Backward Number Range" than RTLE (p < 0.017, p < 0.023, p < 0.004). There were differences between hemispheres for "Number of Items Remembered with a Hint" and "Total number of Recalled Items" (WMS-IV) (p < 0.038, p < 0.045). LTLE had lower scores in the Verbal Fluency -K-A-S letters words and WAIS (Wechsler Adult Intelligence Scale) similarity than RTLE (p < 0.019, p < 0.024, p < 0.033, p < 0.026). Oktem and Boston-number of Self-Named Items Tests were poorer in LTLE than RTLE (p < 0.05, p < 0.043). Mental Control Months-error (WMS-III), "Total Number of Recalled Items", "Number of Items Remembered with Hint" (WMS-IV), forward and backward number range (WMS-V), Oktem, Verbal Fluency -K,-A,-S letters words, WAIS similarity, and Boston-number of Self-Named Items tests, can help identify lateralization, particularly in LTLE.

The who, what, when and why of cognitive difficulties in epilepsy

Cognitive complaints are very common in people diagnosed with epilepsy. These difficulties are often another manifestation of the same pathology responsible for seizures. They can be further exacerbated by treatments aimed at seizure control. Other common comorbidities of epilepsy such as low mood and elevated anxiety can also contribute to cognitive complaints. There is surprisingly little overlap between memory complaints and performance on formal memory tests in this population. This article examines the multifactorial and heterogeneous nature of cognitive difficulties in epilepsy and makes the case for the provision of basic psychoeducation as the foundation for all interventions aimed at ameliorating these difficulties in this patient population.

Cognitive deficits in multiple sclerosis: Auditory and visual attention and inhibitory control

BACKGROUND

A growing body of evidence has been paid to the cognitive impairment in patients with multiple sclerosis (MS). However, studies concerning cognitive functions in MS have also yielded conflicting results. This study investigates the attention and inhibitory control functions in patients with MS and their relationship with other clinical features, such as depression and fatigue in these patients.

METHODS

Participants included 80 patients with MS and 60 healthy controls. The attention and inhibitory control, fatigue, and psychiatric screening in all subjects were studied, respectively with the Integrated Visual and Auditory Continuous Performance Test (IVA-CPT), Fatigue Severity Scale (FSS), and the Hospital Anxiety and Depression Scale (HADS).

RESULTS

Patients with MS performed the IVA-CPT task more poorly than the healthy control group (p < 0.001). However, multiple regression analysis did not show any significant relationship between disease duration, FSS, and HADS on attention and inhibitory control.

CONCLUSION

Inhibitory control and attention are significantly impaired in patients with MS. Finding the basics of cognitive deficits in MS have potentially important clinical implications for developing better cognitive rehabilitation strategies.

Low recognition of attention deficit hyperactivity disorder in adult patients admitted to the Epilepsy Monitoring Unit

INTRODUCTION

Adult patients with epilepsy (PWE) have an 18% prevalence of comorbid attention deficit hyperactivity disorder (ADHD) compared to a prevalence of 2%-5% in the general population. Recognition of this dual diagnosis is important since stimulant therapy is both safe and effective in this population.

METHODS

Here, we aim to determine if PWE have adequate documentation for comorbid ADHD when being admitted to the Epilepsy Monitoring Unit (EMU). A retrospective review was conducted at the Baylor St. Luke's Medical Center EMU for patients presenting between July 2017 and November 2020. Patients were divided into two groups: Group I-patients without a documented ADHD diagnosis or ADHD medications and Group II-patients with a documented ADHD diagnosis and/or taking medications indicated specifically for ADHD.

RESULTS

Of 524 individual patients who presented to the EMU, only 25 patients (4.8%) had documentation of a diagnosis of ADHD and/or ADHD medications (Group II). The proportion of patients in Group II did not significantly differ based on the EMU diagnosis. However, there was a significantly greater number of other psychiatric diagnoses (p = .005) and a greater number of psychiatric medications prescribed (p < .001) in patients in Group II.

CONCLUSION

Our study suggests that ADHD is underrecognized and underdiagnosed in patients presenting to the EMU, and screening tools may be useful to help clinicians address seizure comorbidities such as ADHD.

Mechanisms for Cognitive Impairment in Epilepsy: Moving Beyond Seizures

There has been a major emphasis on defining the role of seizures in the causation of cognitive impairments like memory deficits in epilepsy. Here we focus on an alternative hypothesis behind these deficits, emphasizing the mechanisms of information processing underlying healthy cognition characterized as rate, temporal and population coding. We discuss the role of the underlying etiology of epilepsy in altering neural networks thereby leading to both the propensity for seizures and the associated cognitive impairments. In addition, we address potential treatments that can recover the network function in the context of a diseased brain, thereby improving both seizure and cognitive outcomes simultaneously. This review shows the importance of moving beyond seizures and approaching the deficits from a system-level perspective with the guidance of network neuroscience.

Similar Profile and Magnitude of Cognitive Impairments in Focal and Generalized Epilepsy: A Pilot Study

Introduction: Cognitive impairments in epilepsy are not well-understood. In addition, long-term emotional, interpersonal, and social consequences of the underlying disturbances are important to evaluate.

Purpose: To compare cognitive function including language in young adults with focal or generalized epilepsy. In addition, quality of life and self-esteem were investigated.

Patients and Methods: Young adults with no primary intellectual disability, 17 with focal epilepsy and 11 with generalized epilepsy participated and were compared to 28 healthy controls. Groups were matched on age (mean = 26 years), sex, and education. Participants were administered a battery of neuropsychological tasks and carried out self-ratings of quality of life, self-esteem, and psychological problems.

Results: Similar impairments regarding cognitive function were noted in focal and generalized epilepsy. The cognitive domains tested were episodic long-term memory, executive functions, attention, working memory, visuospatial functions, and language. Both epilepsy groups had lower results compared to controls (effect sizes 0.24–1.07). The total number of convulsive seizures was predictive of episodic long-term memory function. Participants with focal epilepsy reported lower quality of life than participants with generalized epilepsy. Lowered self-esteem values were seen in both epilepsy groups and particularly in those with focal epilepsy. Along with measures of cognitive speed and depression, the total number of seizures explained more than 50% of variation in quality of life.

Conclusion: Interestingly, similarities rather than differences characterized the widespread cognitive deficits that were seen in focal and generalized epilepsy, ranging from mild to moderate. These similarities were modified by quality of life and self-esteem. This study confirms the notion that epilepsy is a network disorder.

Functional seizures are not less important than epilepsy

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People with functional seizures often suffer from psychiatric comorbidities.

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People with FS report detrimental effects on social aspects of their lives.

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FS are associated with a considerable direct and indirect economic burden.

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FS have increased rates of mortality compared to healthy controls.

Functional seizures (FS) are frequently encountered in neurology clinics, often affect young adults, and have significant negative impacts on many aspects of a person’s life. In the current narrative review, we searched the literature regarding some of the consequences of FS (i.e., psychiatric comorbidities, social consequences, costs that are associated with the condition, cognitive impairment in patients with FS, the quality of life of the people with FS, and the increased risk of mortality that is associated with FS). Evidence shows that FS have significant negative consequences, comparable in their magnitude to those affecting patients with epilepsy. The clinical and scientific communities should take steps to address these consequences through clinical care and research that prioritizes, facilitates, and expedites evidence-based diagnosis and treatment for FS.

Executive Functions and Attention in Patients With Psychogenic Nonepileptic Seizures Compared With Healthy Controls: A Cross-Sectional Study

OBJECTIVE

Psychogenic nonepileptic seizures (PNESs) are considered functional neurological symptoms and are highly prevalent in specialized epilepsy clinics. The underlying mechanisms of PNES are not fully understood. Recent findings point toward possible alterations in attention and executive functions. This study aimed to extend the current knowledge of attention and executive function in patients with PNES and to assess possible relationships between seizures and dissociation, childhood trauma, and cognitive function.

METHODS

We recruited 40 patients with PNES and 40 sex-, age-, and education-matched healthy controls (HCs) in this study. Participants completed self-report questionnaires to assess early life stress (Childhood Trauma Questionnaire [CTQ]), dissociation (the German version of the Dissociative Experience Scale, or Fragebogen zu dissoziativen Symptomen), and depression (Patient Health Questionnaire-9). Executive functions and attention were assessed with the Trail Making Test (TMT), Digit Span, and Attention Network Task.

RESULTS

Compared with HCs, patients with PNES reported significantly higher levels of childhood trauma, depression, and dissociation. Patients with PNES also had reduced performance indices for Digit Span Forward (d = 0.62), Digit Span Backward (d = 0.62), and TMT (d = 0.67) but not Attention Network Task. CTQ scores positively correlated with TMT and Digit Span Backward performance in patients with PNES. Adjusting for CTQ scores attenuated the observed group difference in TMT performance. Depression and dissociation did not explain the observed findings.

CONCLUSIONS

These results contribute to the evidence of impaired executive functions in patients with PNES. Furthermore, childhood trauma scores, but not (trait) dissociation or depression scores, seem to drive group differences (HC versus patients with PNES).

The Comparison Between Neuropsychological Features of Psychogenic Non-epileptic Seizures and Epileptic Seizures

Background: Both epileptic seizures (ES) and psychogenic non-epileptic seizures (PNES) are often associated with some degree of cognitive impairment. Video electroencephalography (EEG) monitoring is the gold standard for diagnosing PNES. This diagnostic procedure is costly and available in specific tertiary centers. Neuropsychological assessment can provide clues for the differential diagnosis of PNES and ES and help clarify the nature and etiology of these two disorders. Objectives: Therefore, this study aimed to compare the neuropsychological profiles of PNES and ES patients. Methods: In this analytical cross-sectional study, 30 patients with ES and 31 patients with PNES were compared by neuropsychiatric tests, such as the Wechsler Adult Intelligence scale (WAIS), Addenbrooke’s Cognitive examination (ACE), and California Verbal Learning test (CVLT). Results: There was a female predominance in the PNES group (female-to-male ratio = 4.16/1, P = 0.003). In the PNES group, 77.4% of the patients had a psychiatric disorder versus 66.7% of the patients in the ES group; however, the difference was not statistically significant (P = 0.34). The mean score of total intelligence was higher in the PNES group (84.77 ± 16.94), compared to the ES group (83.63 ± 10.04); however, the difference was not significant (P = 0.75). Based on the mean subscale scores, the digit symbol score (WAIS-IV subscale) and memory score (ACE subscale) were significantly higher in the PNES group compared to the ES group (P = 0.037 and 0.032, respectively). Conclusions: This study showed that neuropsychological assessments might not differentiate ES from non-epileptic seizures.

Attentional Processing and Interpretative Bias in Functional Neurological Disorder

OBJECTIVE

Altered attentional processing (automatically attending to negative or illness-relevant information) and interpretative biases (interpreting ambiguous information as negative or illness relevant) may be mechanistically involved in functional neurological disorder (FND). Common mechanisms between FND and chronic fatigue syndrome (CFS) have been proposed but not compared experimentally.

METHODS

We compared the cognitive task performance of FND, CFS, and healthy control (HC) groups. The tasks assessed attentional bias toward illness-relevant stimuli (visual probe task), attentional control (attention network task), and somatic interpretations (interpretative bias task), alongside self-reported depression, anxiety, fatigue, and general health.

RESULTS

Thirty-seven participants diagnosed with FND, 52 participants diagnosed with CFS, and 51 HC participants were included. Although participants with CFS showed attentional bias for illness-relevant stimuli relative to HC (t = -3.13, p = .002, d = 0.624), individuals with FND did not (t = -1.59, p = .118, d = 0.379). Both the FND (t = 3.08, p = .003, d = 0.759) and CFS (t = 2.74, p = .007, d = 0.548) groups displayed worse attentional control than did the HC group. Similarly, the FND (t = 3.63, p < .001, d = 0.801) and CFS groups (t = 4.58, p < .001, d = 0.909) showed more somatic interpretative bias than did the HC group.

CONCLUSIONS

Similar attentional control deficits and somatic interpretative bias in individuals with FND and CFS support potential shared mechanisms underlying symptoms. Interpretative bias toward somatic and illness-relevant stimuli in functional disorders may prove a therapeutic target.

Behavioral phenotypes of temporal lobe epilepsy

Objective

To identity phenotypes of self‐reported symptoms of psychopathology and their correlates in patients with temporal lobe epilepsy (TLE).

Method

96 patients with TLE and 82 controls were administered the Symptom Checklist 90‐Revised (SCL‐90‐R) to characterize emotional‐behavioral status. The nine symptom scales of the SCL‐90‐R were analyzed by unsupervised machine learning techniques to identify latent TLE groups. Identified clusters were contrasted to controls to characterize their association with sociodemographic, clinical epilepsy, neuropsychological, psychiatric, and neuroimaging factors.

Results

TLE patients as a group exhibited significantly higher (abnormal) scores across all SCL‐90‐R scales compared to controls. However, cluster analysis identified three latent groups: (1) unimpaired with no scale elevations compared to controls (Cluster 1, 42% of TLE patients), (2) mild‐to‐moderate symptomatology characterized by significant elevations across several SCL‐90‐R scales compared to controls (Cluster 2, 35% of TLE patients), and (3) marked symptomatology with significant elevations across all scales compared to controls and the other TLE phenotype groups (Cluster 3, 23% of TLE patients). There were significant associations between cluster membership and demographic (education), clinical epilepsy (perceived seizure severity, bitemporal lobe seizure onset), and neuropsychological status (intelligence, memory, executive function), but with minimal structural neuroimaging correlates. Concurrent validity of the behavioral phenotype grouping was demonstrated through association with psychiatric (current and lifetime‐to‐date DSM IV Axis 1 disorders and current treatment) and quality‐of‐life variables.

Significance

Symptoms of psychopathology in patients with TLE are characterized by a series of discrete phenotypes with accompanying sociodemographic, cognitive, and clinical correlates. Similar to cognition in TLE, machine learning approaches suggest a developing taxonomy of the comorbidities of epilepsy.

Neurochemicals of limbic system and thalamofrontal cortical network: Are they different between patients with idiopathic generalized epilepsy and psychogenic nonepileptic seizure?

OBJECTIVE

Thalamofrontal cortical network and limbic system are proposed to be involved in psychogenic nonepileptic seizure (PNES) and idiopathic generalized epilepsy (IGE). This study aimed to investigate neurochemical changes in prefrontal cortex, thalamus, and limbic circuits in patients with PNES and IGE. We also analyzed the interaction between cognitive functions and neurochemical changes in both groups.

METHODS

Hydrogen proton magnetic resonance spectroscopy (1H-MRS) was used to measure N-acetyl aspartate (NAA), choline (Cho), creatine (Cr), glutamate-glutamine (Glx), and myo-inositol (MI). The voxels were placed on the bilateral dorsolateral prefrontal cortex (DLPFC), dorsomedial prefrontal cortex (DMPFC), anterior cingulate cortex (ACC), and thalamus. Attention and inhibitory control, as well as general intelligence status, were investigated using the Integrated Visual and Auditory Continuous Performance Test (IVA-CPT) and the Wechsler Adult Intelligence Scale (WAIS), respectively, in patients with PNES and IGE, as well as healthy volunteers.

RESULTS

The 1H-MRS showed a decreased ratio of NAA/Cr in the right and left thalamus, right DMPFC, and right ACC in patients with IGE and PNES. Furthermore, a decrease of the NAA/Cr ratio in the left DMPFC and an increase of NAA/Cr ratio in the right DLPFC were observed in patients with PNES compared with the controls. The patient groups had a decreased ratio of Cho/Cr in right ACC compared with the healthy subjects. Moreover, the NAA/Cr ratio in the left thalamus and left DMPFC was correlated with seizure frequency in patient groups. Reduced NAA/Cr ratio in the right ACC and left DLPFC were also correlated with poor IVA-CPT scores.

CONCLUSION

This study highlighted the dysfunction in prefrontal-thalamic-limbic circuits and impairment in neurocognition in patients with PNES and IGE.

A framework for understanding the pathophysiology of functional neurological disorder

The symptoms of functional neurological disorder (FND) are a product of its pathophysiology. The pathophysiology of FND is reflective of dysfunction within and across different brain circuits that, in turn, affects specific constructs. In this perspective article, we briefly review five constructs that are affected in FND: emotion processing (including salience), agency, attention, interoception, and predictive processing/inference. Examples of underlying neural circuits include salience, multimodal integration, and attention networks. The symptoms of each patient can be described as a combination of dysfunction in several of these networks and related processes. While we have gained a considerable understanding of FND, there is more work to be done, including determining how pathophysiological abnormalities arise as a consequence of etiologic biopsychosocial factors. To facilitate advances in this underserved and important area, we propose a pathophysiology-focused research agenda to engage government-sponsored funding agencies and foundations.