Mood state in unilateral temporal lobe epilepsy

Cognitive flexibility impairment in temporal lobe epilepsy: The impact of epileptic foci lateralization on executive functions

INTRODUCTION

Temporal Lobe Epilepsy (TLE) has been associated with memory impairments, which are typically linked to hippocampal and mesial temporal cortex lesions. Considering the presence of extensive bidirectional frontotemporal connections, it can be hypothesized that executive dysfunction in TLE is modulated by the lateralization of the epileptic foci.

MATERIAL AND METHODS

A comprehensive neuropsychological executive functions protocol was administered to 63 participants, including 42 individuals with temporal lobe epilepsy (20 with right-TLE and 22 with left-TLE) and 21 healthy controls aged 20-49.

RESULTS

The results indicate that TLE patients exhibit poorer executive performance compared to healthy controls in working memory (F(2,60) = 4.18, p <.01), planning (F(2,60) = 4.71, p <.05), set shifting (F(2,60) = 10.1, p <.001), phonetic verbal fluency (F(2,60) = 11.71, p <.01) and semantic verbal fluency (F(2,60) = 9.61, p <.001. No significant differences were found in cognitive inhibition. Furthermore, right-TLE patients showed lower performance than left-TLE in set shifting (F(1,61) = 6.45, p <.05), while no significant differences were observed in working memory, planning, inhibition, and verbal fluency.

CONCLUSIONS

This research emphasize the importance of considering the lateralization of the temporal lobe focus to achieve a more accurate neuropsychological characterization. The cognitive differences between left and right TLE patients highlight the need for individualized approaches in their treatment and care.

Stress phenotypes in epilepsy: impact on cognitive functioning and quality of life

Introduction

Drug-resistant epilepsy has been proposed as a chronic stress model. Stress can be measured in terms of chronicity (epilepsy duration) and intensity (comorbidities), with depression and anxiety among the most important comorbidities in epilepsy due to its prevalence and its relationship with cognitive functioning and quality of life. This study aims to establish phenotypes according to how patients face a stressful condition (epilepsy) and examine differences in cognition and quality of life depending on these phenotypes. We hypothesize that there will be an interrelationship between epilepsy duration and negative affectivity, and these variables will influence cognition and quality of life.

Methods

170 patients (82 men and 88 women) underwent a neuropsychological evaluation in which trait anxiety, depression, attention and executive function, verbal and visual memory, language, emotional recognition, and quality of life were assessed. Hierarchical clustering was performed using z-scores for three variables: trait anxiety; depression; and epilepsy duration.

Results

Three clusters were found: vulnerable (high negative affectivity and short duration); resilient (moderate negative affectivity and long duration); and low-impact group (low negative affectivity and short duration). Results show that the vulnerable group had poorer cognitive functioning and quality of life than the other groups. Specifically, the vulnerable group had poorer scores than the low-impact group on verbal memory, visual confrontation naming, and quality of life (except seizure worry). Furthermore, resilient patients had better scores than the low-impact group on cognitive flexibility variables, but lower scores on some quality-of-life subscales (i.e., overall quality of life, emotional well-being, and energy). Finally, the vulnerable group had poorer scores than the resilient group in executive functioning, naming, and quality of life.

Discussion

These results suggest that dealing with stress in patients with epilepsy is related to cognitive performance and quality of life. These findings underline the relevance of considering comorbidities in epilepsy and may be useful for detecting vulnerable or resilient profiles as risk or protective factors for cognitive and quality of life decline.

Interictal Dysphoric Disorder: A disorder with distinct nosography or atypical symptomatology of mood disorders in people with epilepsy? Results from a systematic review

INTRODUCTION

Mood disorders are the most frequent comorbidities in people with epilepsy. The term Interictal Dysphoric Disorder (IDD) has been used to describe a condition where at least three out of eight symptoms must be present for diagnosis. Symptoms are grouped into three symptom clusters of four "labile depressive" symptoms (anergia, depressed mood, insomnia, and pain), two "labile affective" symptoms (anxiety and fear), and two specific symptoms (euphoric moods and paroxysmal irritability), which are described and can be present in people with epilepsy. There is debate about whether IDD is a distinct disease, or if it is simply a special manifestation of mood disorders in epilepsy. For instance, it may represent an atypical presentation of depression in this population.

METHODS

We conducted a systematic review of the literature in 3 databases with the terms "Interictal Dysphoric Disorder" and "mood disorder". A total of 130 articles were selected and, after removing the duplicated applying eligibility criteria, 12 articles were included.

RESULTS

Six articles showed positive evidence for the validation of IDD as an independent nosological entity; in contrast, five articles reported inconclusive findings regarding the question; one explicitly questioned significant differences between IDD and mood disorders as nosological constructs. The data available and presented in this systematic review is insufficient to confirm IDD as a distinct diagnostic category. Nevertheless, it is worth noting other researchers have found some validity in this concept, highlighting the strong connection between mood disorders and epilepsy.

CONCLUSION

Further research in this area is needed, and additional systematic reviews focusing on other aspects of the construct, such as neurobiological mechanisms, may prove to be helpful.

The Thalamic and Intracortical Inhibitory Function of Somatosensory System Is Unchanged in Mesial Temporal Lobe Epilepsy With Hippocampal Sclerosis

PURPOSE

In mesial temporal lobe epilepsy with hippocampal sclerosis, there is parietal atrophy and cognitive involvement in related domains. In this context, we hypothesized that inhibitory input into somatosensory cortex and thalamus may be increased in these patients, which could improve after epilepsy surgery. Thus, we analyzed the inhibitory function of somatosensory system by studying surround inhibition (SI) and recovery function of somatosensory evoked potentials in patients with mesial temporal lobe epilepsy with hippocampal sclerosis.

METHODS

Nine patients with unoperated mesial temporal lobe epilepsy with hippocampal sclerosis, 10 patients who underwent epilepsy surgery, and 12 healthy subjects were included. For SI of somatosensory evoked potentials, we recorded somatosensory evoked potentials after stimulating median or ulnar nerve at wrist separately and after median and ulnar nerves simultaneously and calculated SI% in all participants. For recovery function of somatosensory evoked potentials, paired stimulation of median nerve at 40- and 100-millisecond intervals was performed. We compared the findings among groups. As a secondary analysis, we determined the outliers in the patient group and analyzed the relation to the clinical findings.

RESULTS

The mean SI% or recovery function was similar among three groups. However, there were five patients with SI loss on normal side in the patient group, which was related to the antiseizure drugs.

CONCLUSIONS

In contrast to our hypothesis, both intracortical (SI) and thalamic/striatal (recovery function) inhibitory modulation of the somatosensory cortex was not altered in mesial temporal lobe epilepsy with hippocampal sclerosis and did not differ in surgical and nonsurgical groups.

More than just statics: Static and temporal dynamic changes in intrinsic brain activity in unilateral temporal lobe epilepsy

Background

Temporal lobe epilepsy (TLE) is the most prevalent refractory focal epilepsy and is more likely accompanied by cognitive impairment. The fully understanding of the neuronal activity underlying TLE is of great significance.

Objective

This study aimed to comprehensively explore the potential brain activity abnormalities affected by TLE and detect whether the changes were associated with cognition.

Methods

Six static intrinsic brain activity (IBA) indicators [amplitude of low-frequency fluctuation (ALFF), fractional ALFF (fALFF), regional homogeneity (ReHo), degree centrality (DC), global signal correlation (GSCorr), and voxel-mirrored homotopic connectivity (VMHC)] and their corresponding dynamic indicators, such as dynamic ALFF (dALFF), dynamic fALFF (dfALFF), dynamic ReHo (dReHo), dynamic DC (dDC), dynamic VMHC (dVMHC), and dynamic GSCorr (dGSCorr), in 57 patients with unilateral TLE and 42 healthy volunteers were compared. Correlation analyses were also performed between these indicators in areas displaying group differences and cognitive function, epilepsy duration, and severity.

Results

Marked overlap was present among the abnormal brain regions detected using various static and dynamic indicators, primarily including increased ALFF/dALFF/fALFF in the bilateral medial temporal lobe and thalamus, decreased ALFF/dALFF/fALFF in the frontal lobe contralateral to the epileptogenic side, decreased fALFF, ReHo, dReHo, DC, dDC, GSCorr, dGSCorr, and VMHC in the temporal neocortex ipsilateral to the epileptogenic foci, decreased dReHo, dDC, dGSCorr, and dVMHC in the occipital lobe, and increased ALFF, fALFF, dfALFF, ReHo, and DC in the supplementary motor area ipsilateral to the epileptogenic foci. Furthermore, most IBA indicators in the abnormal brain region significantly correlated with the duration of epilepsy and several cognitive scale scores (P < 0.05).

Conclusion

The combined application of static and dynamic IBA indicators could comprehensively reveal more real abnormal neuronal activity and the impairment and compensatory mechanisms of cognitive function in TLE. Moreover, it might help in the lateralization of epileptogenic foci and exploration of the transmission and inhibition pathways of epileptic activity.

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.

Mechanisms of cognitive impairment in temporal lobe epilepsy: A systematic review of resting-state functional connectivity studies

Temporal lobe epilepsy is the most common form of focal epilepsy and related cognitive dysfunction impacts significantly on quality of life in patients. Identifying the mechanisms of such impairment would assist in the management and treatment of patients. The study of perturbations in resting-state networks could shed light on this subject. The aim of this systematic review was to synthesize findings on the relationship between aberrant resting-state functional connectivity and cognitive performance in patients with TLE. Literature searches were conducted on Scopus and PubMed electronic databases and 17 relevant articles were extracted, all of which studied the association between resting-state functional connectivity (RSFC) and cognition in adults with TLE. Study findings were synthesized according to methods used to analyze resting-state data, cognitive domains tested, and neuropsychology tasks administered. Results show that increased RSFC in the primary epileptogenic hippocampus, and reduced intra-hemispheric RSFC, are associated with weaker memory performance. In left TLE, memory impairment may be compensated for by bilateral hippocampal connectivity, which is also predictive of better postoperative memory outcomes. In right TLE, memory loss may be compensated for by increased connectivity between the contralateral hippocampus and inferior frontal gyrus. There is also tentative evidence that working memory dysfunction is related to reduced RSFC between the medial frontal-insular parietal network and the medial temporal network, executive dysfunction is related to reduced RSFC between frontal and parietal lobes, and between the frontal lobe and subcortical regions and that language dysfunction is related to reduced RSFC within the left fronto-temporal language network. Multicenter studies could refute or support these findings by enrolling large samples of patients and employing multivariate regression analysis to control for the effects of anatomical disruption, interictal discharges, seizure frequency, medication, and mood. Systematic review registration: PROSPERO: 191323.

5-HT/GABA interaction in epilepsy

Epilepsy is a neurological condition characterized by synchronous neuronal oscillations (seizures) in the electroencephalogram. Seizures are classified in focal or generalized (depending on the brain territory interested during seizures), and in convulsive and/or not convulsive (depending on the presence or not of involuntary movements). The current pharmacological treatments are mainly based on GABA modulation although different neurotransmitters are also involved in epilepsy, including serotonin. However despite much extensive progress in the understanding of epilepsy mechanisms, still, a percentage of people with epilepsy are pharmaco-resistant calling for the need for new therapeutic targets. Here we review preclinical and human evidence showing that serotonin modulates epilepsy that this likely happens via a major modulation/interaction with GABA.

Cognitive impairment in temporal lobe epilepsy: contributions of lesion, localization and lateralization

BACKGROUND

Cognitive impairment is an important comorbidity of refractory temporal lobe epilepsy (TLE). We aimed to explore the impact of (i) specific lesions, such as dysembryoplastic neuroepithelial tumor (DNET), dysplasia, or hippocampal sclerosis, (ii) focus localization (medial versus lateral) and (iii) focus lateralization (right versus left) on the neuropsychological profile of refractory TLE adult patients.

METHODS

We examined the neuropsychological characteristics of 312 adults with refractory TLE: 100 patients without hippocampal sclerosis (HS) and 212 with HS. Scores on tests of intelligence (Global IQ, Verbal IQ and Performance IQ), working memory, episodic memory (verbal and visual learning and forgetting), executive functions and language abilities were analyzed.

RESULTS

Three main factors influenced the neuropsychological profile of refractory TLE patients: (i) the lesion, patients with HS obtaining poorer cognitive performances than patients without HS and specifically DNET patients performing better than patients with HS, (ii) the focus side, that seems only relevant for verbal memory abilities which are affected in left but not right TLE patients and (iii) the localization of seizure focus, patients with medial TLE exhibiting lower memory performances than patients with lateral TLE.

CONCLUSION

Lesion, localization and lateralization are major contributors of the cognitive impairment depicted in TLE. Hippocampal sclerosis appears as the main contributor.

Depression could modulate neuropsychological status in epilepsy

While cognition and depression have often been studied in patients with epilepsy, only a few studies have so far attempted to link these two domains, and more specifically to investigate the specific impact of depression on cognition in epilepsy. In this review, we performed an extensive search of the literature database to provide a better understanding of this subject. Using several inclusion criteria (adult population, quantitative depression/neuropsychological assessment, statistical analyses of the impact of depression on cognitive scores, patients with epilepsy (PWE) and no other neurological disease, and studies including at least 20 patients), we identified 20 articles (out of 712 search results) that investigated both depression and cognition in PWE. Their results were summarized using a narrative and descriptive approach. This review highlights a variable impact of depression on cognition in PWE, depending on the laterality of the seizure onset zone, the type of epilepsy and the surgical context. We emphasize the need for a systematic depression assessment in these patients, especially since depressed PWE will benefit from prompt and appropriate care to help them avoid cognitive decline, particularly in a surgical context.

The effect of left and right long-term amygdala kindling on interictal emotionality and Fos expression

Clinical observations have often reported that patients with seizures arising from limbic structures on the right side of the brain have a higher incidence of emotional disturbances, such as fear and anxiety, than those who have seizures lateralized to limbic structures on the left side. However, there have been some inconsistent reports regarding the presence of these laterality effects. The use of animal models of epilepsy can help circumvent many of the methodological and ethical issues that arise from human clinical studies. In the present study, we examined the unique contribution of left- or right-sided long-term kindling of the amygdala on the development of interictal emotional disturbances. Following kindling to 99 electrical stimulations, male kindled and control rats were examined on a series of behavioral tests - open-field exploration, elevated plus maze, forced swim, and social interaction. Our results revealed that long-term amygdala kindling, irrespective of the hemisphere stimulated, increased general behavioral hyperactivity and fearful behavior. Interestingly, rats that were kindled from the left amygdala showed greater social avoidance and defensive behaviors during interactions with another kindled conspecific. To examine the brain structures that support long-term kindling, we also examined the expression of the immediate early gene product Fos 1 h after rats received their last electrical stimulation. Compared with control rats, kindled rats had increased Fos expression in several brain regions (e.g., piriform, frontal motor cortex, perirhinal cortex) involved in the generation and development of epilepsy. However, decreased Fos expression was also observed in several subregions of the hippocampus and amygdala that are known to be important fear behavior and memory. These findings suggest that both left and right amygdala kindling produce similar changes in emotional behavior and support the idea that the development of kindled fear may result from reduced activation of specific hippocampal and amygdaloid circuits.

Neuroanatomical correlates of personality traits in temporal lobe epilepsy: Findings from the Epilepsy Connectome Project

Behavioral and personality disorders in temporal lobe epilepsy (TLE) have been a topic of interest and controversy for decades, with less attention paid to alterations in normal personality structure and traits. In this investigation, core personality traits (the Big 5) and their neurobiological correlates in TLE were explored using the Neuroticism Extraversion Openness-Five Factor Inventory (NEO-FFI) and structural magnetic resonance imaging (MRI) through the Epilepsy Connectome Project (ECP). NEO-FFI scores from 67 individuals with TLE (34.6 ± 9.5 years; 67% women) were compared to 31 healthy controls (32.8 ± 8.9 years; 41% women) to assess differences in the Big 5 traits (agreeableness, openness, conscientiousness, neuroticism, and extraversion). Individuals with TLE showed significantly higher neuroticism, with no significant differences on the other traits. Neural correlates of neuroticism were then determined in participants with TLE including cortical and subcortical volumes. Distributed reductions in cortical gray matter volumes were associated with increased neuroticism. Subcortically, hippocampal and amygdala volumes were negatively associated with neuroticism. These results offer insight into alterations in the Big 5 personality traits in TLE and their brain-related correlates.

Standardization of an Arabic-Language Neuropsychological Battery for Epilepsy Surgical Evaluations

OBJECTIVES

This study provides a standardized Arabic language neuropsychological test battery and tests its ability to distinguish patients with left and right hemisphere epileptic foci who are candidates for surgical resection.

METHODS

An Arabic language battery of 15 tests was developed based on the neuropsychological test battery used at the Johns Hopkins Hospital for surgical evaluation of patients undergoing temporal lobe resection. With modifications where culturally required, 11 tests were translated to Arabic by the principal investigator and back-translated by two bilingual health professionals; four tests were available in Arabic and added to the battery. The battery was administered to 21 Arabic-speaking patients with left temporal epileptic foci, 21 with right temporal epileptic foci, and 46 neurologically and psychiatrically healthy adults.

RESULTS

Nearly all the Arabic test versions were capable of differentiating healthy controls and the temporal lobe epilepsy (TLE) groups. Tests known to distinguish left and right temporal lobectomy candidates, such as wordlist memory and prose recall, were able to do so as accurately as the English versions. Also, a roughly "culturally free" task (the Baltimore Board) and a newly developed version of the Boston Naming Test demonstrated some sensitivity to left temporal lobe involvement.

CONCLUSIONS

Arabic-language neuropsychological tests for epilepsy surgical evaluations are made available, demonstrate cultural sensitivity and clinical validity, and require further psychometric property and normative research. (JINS, 2019, 25, 761-771).

Temporal lobe epilepsy is associated with distinct cognitive phenotypes

Neuropsychological assessment is critical for understanding the impact of seizures on cognition and informing treatment decisions. While focus is often placed on examining groups based on seizure type/epilepsy syndrome, an alternate approach emphasizes empirically derived groups based solely on cognitive performance. This approach has been used to identify cognitive phenotypes in temporal lobe epilepsy (TLE). The current study sought to replicate prior work by Hermann and colleagues (2007) and identify cognitive phenotypes in a separate, larger cohort of 185 patients with TLE (92 left TLE, 93 right TLE). Cluster analysis revealed 3- and 4-cluster solutions, with clusters differentiated primarily by overall level of performance in the 3-cluster solution (Low, Middle, and High performance) and by more varying cognitive phenotypes in the 4-cluster solution (Globally Low, Low Executive Functioning/Speed, Low Language/Memory, and Globally High). Differences in cognitive performance as well as demographic and clinical seizure variables are presented. A greater proportion of the patients with left TLE were captured by Cluster 3 (Low Language/Memory) than by the other 3 clusters, though this cluster captured only approximately one-third of the overall group with left TLE. Consistent with prior findings, executive functioning and speed emerged as additional domains of interest in this sample of patients with TLE. The current results extend prior work examining cognitive phenotypes in TLE and highlight the importance of identifying the comprehensive range of potential cognitive profiles in TLE.

Epilepsy, depression, and growth hormone

Depression affects a large proportion of patients with epilepsy, and is likely due in part to biological mechanism. Hormonal dysregulation due to the disruptive effects of seizures and interictal epileptiform discharges on the hypothalamic-pituitary-adrenal axis likely contributes to high rates of depression in epilepsy. This paper reviews the largely unexplored role of neuroendocrine factors in epilepsy-related depression, focusing on Growth Hormone (GH). While GH deficiency is traditionally considered a childhood disorder manifested by impaired skeletal growth, GH deficiency in adulthood is now recognized as a serious disorder characterized by impairments in multiple domains including mood and quality of life. Could high rates of depression in patients with epilepsy relate to subtle GH deficiency? Because GH replacement therapy has been shown to improve mood and quality of life in patients with GH deficiency, this emerging area may hold promise for patients suffering from epilepsy-related depression.

Are mental distress and cognitive impairment related in temporal lobe epilepsy?

OBJECTIVE

Cognitive impairment and depression often co-exist among patients with epilepsy. However, there is still debate whether depression and cognition are related in patients with temporal lobe epilepsy (TLE). Even if they were related, it is still unclear whether symptoms of depression specifically, or rather symptoms of mental distress in general, have a negative impact on cognition in patients with TLE. In the present study, we examined whether self-rated symptoms of mental distress and of depression are related to different cognitive functions in unilateral TLE.

METHODS

We retrospectively studied 162 patients undergoing preoperative evaluation for epilepsy surgery (95 patients with left TLE (LTLE) and 67 patients with right TLE (RTLE)). Severity of mental distress and symptoms of depression were measured with the Symptom Checklist-90-Revised (SCL-90-R) and the Beck Depression Inventory (BDI), respectively. Bivariate correlations were calculated between these two measures and neuropsychological measures of verbal recall, figural learning, psychomotor speed, and phonemic word fluency. Due to multiple testing, a corrected level of p < 0.0063 was regarded as significant, only.

RESULTS

Seventeen and 19% of patients reported meaningful mental distress and meaningful symptoms of depression, respectively. Mental distress highly correlated with symptoms of depression (r_s = 0.80). We found no significant correlations of either mental distress or symptoms of depression with measures of cognitive function.

CONCLUSIONS

In contrast to some former studies with smaller sample sizes, the present study could not detect a relationship of depression with cognitive impairment in patients with unilateral TLE. Likewise, mental distress and cognition were unrelated in our sample of patients. Our results may argue against theoretical models claiming a causal link between depression and cognitive impairment or a common pathogenic mechanism for these conditions in patients with TLE.

Effects of surgical side and site on psychological symptoms following epilepsy surgery in adults

This retrospective study examined the potential role of side and site of surgery in psychological symptom change after epilepsy surgery and determined the base rate of psychological change at the individual level. Two-hundred twenty-eight adults completed the Personality Assessment Inventory (PAI) before and after temporal (TLR; n=190) or frontal lobe resection (FLR; n=38). Repeated measures ANOVAs with bootstrapping examined differences in psychological outcome as a function of surgical site separately in patients who underwent left- versus right-sided resections. Individual's PAI score changes were then used to determine the prevalence of clinically meaningful postoperative symptom change. Following left-sided resections, there were significant group-by-time interactions on Somatic Complaints, Anxiety, and Anxiety Related Disorders. There was also a trend in this direction on the Depression scale. TLR patients endorsed greater preoperative symptoms than FLR patients on all of these scales, except the Somatic Complaints scale. After surgery, TLR patients reported symptom improvement on all four scales, while scores of FLR patients remained relatively stable over time. Endorsement of Mania-related symptoms increased in both TLR and FLR groups from pre-to post-surgical testing. Following right-sided resections, both groups endorsed symptom improvements on Somatic Complaints, Anxiety, and Depression scales following surgery. In addition, the TLR group endorsed more Mania-related symptoms than the FLR group regardless of time. Patterns of meaningful change in individual patients were generally consistent with group findings, with the most frequent improvements observed following TLR. However, there were a small subset of patients who reported symptom exacerbation after surgery. Our results suggest that surgical lateralization and localization are important factors in postoperative psychological outcome and highlight the importance of considering psychological change at the individual patient level. Further research is needed to identify potential risk factors for symptom exacerbation to aid in preoperative counseling and identify those patients most in need of postoperative psychological surveillance.

The relationship of seizure focus with depression, anxiety, and health-related quality of life in children and adolescents with epilepsy

For youth with epilepsy, comorbid psychiatric conditions, such as depression and anxiety, require further examination as they carry increased risk for reduced health-related quality of life (HRQOL). The current study assessed whether rates of depression, anxiety, and withdrawal behaviors differed based on seizure location. Data included parental ratings on the Behavior Assessment System for Children (BASC-2) and the Quality of Life in Childhood Epilepsy (QOLCE) questionnaire for 132 children and adolescents (mean age=11.34, SD=3.95) with generalized or partial (i.e., frontal [FLE] or temporal lobe epilepsy [TLE]) epilepsy. Our results identified clinically significant internalizing psychopathology in nearly half of our sample (41%). Although rates of internalizing behavior were similar between generalized and partial groups, children and adolescents with TLE demonstrated higher rates of depression compared to youth with FLE. No effects of laterality on internalizing behaviors were identified between TLE and FLE groups. Finally, for youth with TLE, parental depression ratings along with current number of antiepileptic medications (AEDs) were found to be significant barriers to HRQOL above and beyond anxiety, withdrawal, and epilepsy-specific variables. Temporal lobe epilepsy was associated with a two-fold risk of clinically significant depression ratings. These findings highlight the high prevalence of internalizing psychopathology features in pediatric epilepsy and offer further support for the relationship between depression and TLE in children and adolescents with epilepsy.

The Contribution of Cognitive Networks to Depression in Epilepsy

This review poses the question: Does disruption to cognitive brain networks in epilepsy contribute to the problem of comorbid depression? Initial evidence suggests that the network disease that gives rise to seizures has a predilection for the same cognition-related networks that regulate mood, with comorbidity reflective of more extensive disease. Framing both epilepsy and its psychiatric comorbidities in terms of dysfunction in overlapping (cognitive) networks raises the possibility that depression can be a primary feature of the disease in some cases and facilitates an epilepsy classification system where behavioral features of the disorder are embedded in a neurobiological mechanism.

Identifying clinical correlates for suicide among epilepsy patients in South Korea: A case-control study

OBJECTIVE

Suicide is a major cause of premature mortality in patients with epilepsy. We aimed to identify the clinical correlates of suicide in these patients.

METHODS

We conducted a matched, case-control study based on a clinical case registry of epilepsy patients (n = 35,638) treated between January 1994 and December 2011 at an academic tertiary medical center in Seoul, Korea. Each epilepsy patient in the suicide group (n = 74) was matched with three epilepsy patients in the nonsuicide group (n = 222) by age, gender, and approximate time at first treatment. The clinical characteristics of the patients in both groups were then compared.

RESULTS

In a univariate analysis, seizure frequency during the year before suicide, use of antiepileptic drug polytherapy, lack of aura before seizure, diagnosis of temporal lobe epilepsy, use of levetiracetam, psychiatric comorbidity, and use of antidepressants were all significantly higher in the suicide group than in the nonsuicide group. Multivariate analysis revealed that a high seizure frequency (odds ratio [OR] 3.3, 95% confidence interval [CI] 1.04-10.2), a lack of aura before seizure (OR 4.0, 95% CI 1.7-9.3), temporal lobe epilepsy (OR 3.7, 95% CI 1.6-8.6), and use of levetiracetam (OR 7.6, 95% CI 1.1-53.7) and antidepressants (OR 7.2, 95% CI 1.5-34.1) were all associated with a higher probability of suicide.

SIGNIFICANCE

Patients with temporal lobe epilepsy who experience seizures weekly or more frequently, experience a lack of aura, use levetiracetam, or take antidepressants are all at a higher risk of suicide and should be monitored closely.

Functional connectivity homogeneity correlates with duration of temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is often associated with progressive changes to seizures, memory, and mood during its clinical course. However, the cerebral changes related to this progression are not well understood. Because the changes may be related to changes in brain networks, we used functional connectivity MRI (fcMRI) to determine whether brain network parameters relate to the duration of TLE. Graph theory-based analysis of the sites of reported regions of TLE abnormality was performed on resting-state fMRI data in 48 subjects: 24 controls, 13 patients with left TLE, and 11 patients with right TLE. Various network parameters were analyzed including betweenness centrality (BC), clustering coefficient (CC), path length (PL), small-world index (SWI), global efficiency (GE), connectivity strength (CS), and connectivity diversity (CD). These were compared for patients with TLE as a group, compared to controls, and for patients with left and right TLE separately. The association of changes in network parameters with epilepsy duration was also evaluated. We found that CC, CS, and CD decreased in subjects with TLE compared to control subjects. Analyzed according to epilepsy duration, patients with TLE showed a progressive reduction in CD. In conclusion, we found that several network parameters decreased in patients with TLE compared to controls, which suggested reduced connectivity in TLE. Reduction in CD associated with epilepsy duration suggests a homogenization of connections over time in TLE, indicating a reduction of the normal repertoire of stronger and weaker connections to other brain regions.

Neuropsychological deficits in temporal lobe epilepsy: A comprehensive review

Temporal lobe epilepsy (TLE) is the most prevalent form of complex partial seizures with temporal lobe origin of electrical abnormality. Studies have shown that recurrent seizures affect all aspects of cognitive functioning, including memory, language, praxis, executive functions, and social judgment, among several others. In this article, we will review these cognitive impairments along with their neuropathological correlates in a comprehensive manner. We will see that neuropsychological deficits are prevalent in TLE. Much of the effort has been laid on memory due to the notion that temporal lobe brain structures involved in TLE play a central role in consolidating information into memory. It seems that damage to the mesial structure of the temporal lobe, particularly the amygdale and hippocampus, has the main role in these memory difficulties and the neurobiological plausibility of the role of the temporal lobe in different aspects of memory. Here, we will cover the sub-domains of working memory and episodic memory deficits. This is we will further proceed to evaluate the evidences of executive function deficits in TLE and will see that set-shifting among other EFs is specifically affected in TLE as is social cognition. Finally, critical components of language related deficits are also found in the form of word-finding difficulties. To conclude, TLE affects several of cognitive function domains, but the etiopathogenesis of all these dysfunctions remain elusive. Further well-designed studies are needed for a better understanding of these disorders.

Functional connectivity of hippocampal networks in temporal lobe epilepsy

OBJECTIVE

Temporal lobe epilepsy (TLE) affects brain areas beyond the temporal lobes due to connections of the hippocampi and other temporal lobe structures. Using functional connectivity magnetic resonance imaging (MRI), we determined the changes of hippocampal networks in TLE to assess for a more complete distribution of abnormality.

METHODS

Regions of interest (ROIs) were defined in the right and left hippocampi in three groups of participants: left TLE (n = 13), right TLE (n = 11), and healthy controls (n = 16). Brain regions functionally connected to these ROIs were identified by correlating resting-state low-frequency functional MRI (fMRI) blood oxygenation level-dependent (BOLD) signal fluctuations. The grouped results were compared using independent sample t-test.

RESULTS

TLE was associated with increased hippocampal connectivity involving several key areas of the limbic network (temporal lobe, insula, thalamus), frontal lobes, angular gyrus, basal ganglia, brainstem, and cerebellum, along with reduced connectivity involving areas of the sensorimotor cortex (visual, somatosensory, auditory, primary motor) and the default mode network (precuneus). Left TLE had more marked connectivity changes than right TLE.

SIGNIFICANCE

The observed connectivity changes in TLE indicate dysfunctional networks that underlie widespread brain involvement in TLE. There are identifiable differences in the connectivity of the hippocampi between left and right TLE.

Alterations in functional connectivity between the hippocampus and prefrontal cortex as a correlate of depressive symptoms in temporal lobe epilepsy

Depression is a common comorbidity in temporal lobe epilepsy (TLE) that is thought to have a neurobiological basis. This study investigated the functional connectivity (FC) of medial temporal networks in depression symptomatology of TLE and the relative contribution of structural versus FC measures. Volumetric MRI and functional connectivity MRI (fcMRI) were performed on nineteen patients with TLE and 20 controls. The hippocampi and amygdalae were selected as seeds, and five prefrontal and five cingulate regions of interest (ROIs) were selected as targets. Low-frequency blood-oxygen-level-dependent signals were isolated from fcMRI data, and ROIs with synchronous signal fluctuations with the seeds were identified. Depressive symptoms were measured by the Beck Depression Inventory-II. The patients with TLE showed greater ipsilateral hippocampal atrophy (HA) and reduced FC between the ipsilateral hippocampus and the ventral posterior cingulate cortex (vPCC). Neither HA nor hippocampal-vPCC FC asymmetry was a robust contributor to depressive symptoms. Rather, hippocampal-anterior prefrontal FC was a stronger contributor to depressive symptoms in left TLE (LTLE). Conversely, right amygdala FC was correlated with depressive symptoms in both patient groups, with a positive and negative correlation in LTLE and right TLE (RTLE), respectively. Frontolimbic network dysfunction is a strong contributor to levels of depressive symptoms in TLE and a better contributor than HA in LTLE. In addition, the right amygdala may play a role in depression symptomatology regardless of the side of the epileptogenic focus. These findings may inform the treatment of depressive symptoms in TLE and inspire future research to help guide surgical planning.

Specificity of psychopathology in temporal lobe epilepsy

An investigation into the specificity of psychopathology in temporal lobe epilepsy was conducted using the Minnesota Multiphase Personality Inventory second edition (MMPI-2) profiles. Consecutive series of patients with left temporal lobe epilepsy (n = 49) and those with right temporal lobe epilepsy (n = 45) were compared with patients with other forms of epilepsy (n = 46) and other heterogeneous neurological conditions (n = 69). The investigation focused on the Clinical, Content, and Subscales scales that resembled descriptions of the Interictal Dysphoric Disorder symptoms and Temporal Lobe Epilepsy Personality Traits. Patients with right temporal lobe epilepsy and those with left temporal lobe epilepsy did not have different patterns of scale elevation, nor did they have clinical elevations compared with patients with other types of epilepsy or neurological controls. The MMPI-2 scales that resemble descriptions of the Interictal Dysphoric Disorder or Temporal Lobe Epilepsy Personality Syndrome were not elevated in either group of patients with temporal lobe epilepsy compared with the group of patients with non-temporal lobe epilepsy or heterogeneous neurological controls. This study adds to the mounting body of empirical research that has used standardized measures and matched groups, but failed to detect a special affinity between psychopathology and temporal lobe epilepsy.

Executive functioning and depressed mood before and after unilateral frontal lobe resection for intractable epilepsy

Executive dysfunction occurs in a variety of patients who have sustained damage to the frontal lobes. In individuals with frontal lobe epilepsy (FLE) or after unilateral frontal lobe resection (FLR), a unique neuropsychological profile linking executive functions (EF) with the frontal lobe has been elusive, with conflicting findings in the literature. Some studies show greater risk of executive impairment with left-sided FLE or FLR, while others report greater risk for right-sided patients. Some studies report no relationship between FLE and EF impairment, while others show EF impairment regardless of side of seizure foci or surgery. In patients with temporal lobe epilepsy, executive dysfunction is associated with depressed mood possibly reflecting disruption of cortical-limbic pathways and/or frontal-striatal circuitry. Although not previously examined, depression level may affect executive functioning in those with FLE or FLR. We hypothesized that FLE patients with poor mood state would show greater executive dysfunction than FLE patients without poor mood state. The relationship among EF, side of surgery and depressed mood before and 8 months after unilateral FLR was evaluated in 64 patients using validated measures of EF and mood state (Beck Depression Inventory-II). Results indicated that individuals with depressed mood before surgery had greater difficulty on a task of mental flexibility compared to patients without preoperative depressed mood. Further, individuals with depressed mood before surgery had significant increases in perseverative responding and completed fewer categories on a card-sorting task after surgery compared to patients without preoperative depressed mood. Regression analyses showed that among side of surgery, seizure freedom status after surgery and depression status, only pre-surgical depression status explained a significant amount of variance in executive functioning performance after surgery. Results suggest that clinically elevated depressive symptoms before surgery are a risk factor for moderate declines in EF after surgery. Results may be attributable to reduced cognitive reserve in patients with depressive symptoms, or may reflect a common cause attributable to damage to unilateral dorsal and ventral lateral frontal lobe.

Frontal lobe function in temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is typically associated with long-term memory dysfunction. The frontal lobes support high-level cognition comprising executive skills and working memory that is vital for daily life functioning. Deficits in these functions have been increasingly reported in TLE. Evidence from both the neuropsychological and neuroimaging literature suggests both executive function and working memory are compromised in the presence of TLE. In relation to executive impairment, particular focus has been paid to set shifting as measured by the Wisconsin Card Sorting Task. Other discrete executive functions such as decision-making and theory of mind also appear vulnerable but have received little attention. With regard to working memory, the medial temporal lobe structures appear have a more critical role, but with emerging evidence of hippocampal dependent and independent processes. The relative role of underlying pathology and seizure spread is likely to have considerable bearing upon the cognitive phenotype and trajectory in TLE. The identification of the nature of frontal lobe dysfunction in TLE thus has important clinical implications for prognosis and surgical management. Longitudinal neuropsychological and neuroimaging studies assessing frontal lobe function in TLE patients pre- and postoperatively will improve our understanding further.

Explicit and implicit emotional processing modifications in pharmacoresistant left temporal lobe epilepsy and anxiodepressive disorders

We examined whether anxiodepressive patients with left temporal lobe epilepsy could be differentiated from those with depression but without epilepsy on tasks that investigate attentional bias toward and explicit judgment of emotional stimuli. Eight depressive patients, eight anxiodepressive patients with epilepsy, and eight controls participated in the present study. Anxiodepressive with epilepsy and depressive patients had comparable depression scores and the same cognitive profile. Two distinct emotional tasks were used: the decision lexical task and the number comparison task. Three emotional connotations were presented: neutral, positive, and negative. The pattern of results showed an attentional bias toward negative words and pictures in depressive patients and only toward negative words in anxiodepressive patients with epilepsy. Moreover, depressive patients explicitly judged negative stimuli with lower intensity and anxiodepressive patients judged neutral stimuli with higher intensity. The present study specifies the emotional functioning in depression with or without left temporal lobe epilepsy.

Depression in epilepsy: mechanisms and therapeutic approach

In patients with epilepsy, mood disorders represent a frequent psychiatric comorbidity but they often remain unrecognized and untreated. However, comorbid depression may have a major impact on the quality of life of patients with epilepsy, sometimes even more than the seizures. Among the potential neurobiological and psychosocial determinants, epilepsy-related variables (age at onset of seizures, temporal lobe epilepsy and frequency of seizures) and the antiepileptic drug treatment have been associated with depression. Nonetheless, data on treatment strategies are still limited with a lack of controlled trials on the use of antidepressant drugs. Moreover, the issue of psychotropic drug treatment of depression in epilepsy is interlinked with that of worsening seizures. This paper is aimed at discussing all these subjects in the light of current literature on the neurobiology of depression in epilepsy.

Association of epilepsy and comorbid conditions

Comorbid health conditions are common among people with epilepsy. Proposed explanations for this association include the possibility that first, epilepsy (including its treatment) causes the comorbid condition; second, the comorbid condition (including its treatment) causes epilepsy; or third, a common pathogenic mechanism mediates the co-occurrence of epilepsy and the comorbid condition. It is unlikely that a single explanation will suffice for all of the epilepsy comorbid conditions. Determining the basis of the association between epilepsy and its comorbid conditions has important implications for diagnosis and management. In this paper, we discuss this issue in the context of five common epilepsy comorbid conditions: bone health and fractures, stroke, depression, migraine and attention-deficit hyperactivity disorder. Current findings, research limitations and future directions of research efforts are discussed.

The effects of epilepsy and its treatments on affect and emotion

Epilepsy creates significant morbidity, disability, and loss of productivity worldwide. Although unpredictable seizures define epilepsy, the cognitive and emotional difficulties encountered by people with epilepsy may have an even greater impact on everyday function. Epilepsy is associated with lower quality of life (QOL); while this is partially attributable to ongoing seizures, QOL is independently affected by comorbid affective disorders like depression and anxiety. These can accompany all types of epilepsy, but may be especially noteworthy in partial epilepsy syndromes with foci in the frontal or temporal lobes. There is growing evidence that epileptogenic lesions disrupt cortical networks that carry out emotional processing. In addition to epilepsy itself, treatment strategies also affect cognitive functioning and mood. Antiepileptic drugs, vagal nerve stimulation, and surgical resection have all been associated with changes in mood, emotional processing, and social cognition. Overall, the relationship between epilepsy and emotion is vastly complex; when assessing emotional difficulties in a person with epilepsy, we must consider the psychosocial impact of the disease on the patient, the underlying pathophysiology of the disease, and the effects of ongoing treatments.

Depression and anxiety in children and adolescents with epilepsy: prevalence, risk factors, and treatment

Among the psychiatric comorbid conditions in children and adolescents with epilepsy, depression and anxiety disorders require further attention because they carry the risk of reduced quality of life and life-threatening complications (e.g., suicide). Research in recent years has shed light on both the prevalence of emotional problems in youth with epilepsy and the safety and efficacy of treatment options. A number of challenges exist in treating patients with epilepsy. This is particularly true when seizures are difficult to control and medication regimens are more complex. Some pharmaceutical options may provide assistance with both seizures and emotional distress, but care is needed when considering such treatment approaches. In addition, integration of mental health professionals into the care of patients is necessary when cases are complicated and risk factors are high. Thorough methods to accurately diagnose emotional conditions and regular monitoring of symptoms can help prevent serious problems that can negatively affect the success of children and adolescents in everyday life. Collaboration between disciplines offers the best hope for early identification and treatment of these conditions.

Suicidality and Antiepileptic Drugs

The main purpose of the present article is to review the possible risk factors for suicidal behaviour in epilepsy with a special emphasis on the different antiepileptic drugs (AEDs). Epidemiological data show that, in general, the suicide rate among patients with epilepsy is 5-fold higher than that in the general population, while in temporal lobe epilepsy and complex partial seizures it is approximately 25-fold higher. A certain psychiatric comorbidity may provoke suicidality in patients with epilepsy, and depression and cognitive impairment seem to be the main risk factors for suicidality in epilepsy. In addition, depression and cognitive deterioration in epilepsy may share common neuropsychological mechanisms in terms of hypofrontality. This may cause similar psychopathological signs in both diagnostic categories, including suicidality. Analysis of the literature has shown that serotonin metabolism disturbances are involved in the pathogenesis of suicidal behaviour irrespective of primary diagnosis. Serotonin disturbances also seem to be a common link between depression, suicidality and even epilepsy itself. The various AEDs differ not only in their mechanisms of action, but also in influences on cognition and mood in epileptic patients and suicidality, respectively. Until now, only Ketter's hypothesis has been proposed to explain the psychotropic effects of different AEDs, although it does not explain the positive psychotropic effects of some AEDs, such as carbamazepine and oxcarbazepine. According to this model, all psychotropic effects of AEDs may be the result of effects on the function of two types of receptor functions: gamma-aminobutyric acid (GABA) ergic and antiglutamatergic; other possible mechanisms have not been incorporated. Presumably, other neurochemical mechanisms, and a serotonergic mechanism in particular, should also be taken into account when explaining the psychotropic effects of different AEDs. Based on these data, it has been suggested that AEDs with certain serotonergic properties should reduce the suicidality risk because they exert effects similar to antidepressants (i.e. selective serotonin reuptake inhibitors), whereas AEDs that lack serotonergic mechanisms would not be effective in suicidality prevention. In line with this paradigm, phenobarbital and phenytoin seem to be the only drugs with proven suicidality risk. On the other hand, carbamazepine, oxcarbazepine, valproate and lamotrigine could be regarded as drugs with antisuicidal properties because they all improve cognitive functions and mood in epileptic patients, and possess serotonergic mechanisms of action. The other AEDs, including topiramate, tiagabine, vigabatrin, levetiracetam and zonisamide, all exert negative effects on mood and cognition, although their influence on suicidality has not been proven in evidence-based studies yet. Although zonizamide has serotonergic properties, it exerts negative psychotropic effects, whereas gabapentin is devoid of serotonergic properties but has positive psychotropic effects on mood and cognition. To more fully explain the positive and negative psychotropic effects and influence on suicidality of AEDs, Ketter's paradigm should be supplemented by an understanding of the serotonergic mechanisms of different AEDs. Further trials are required to prove or refute this model.

Interictal Depression, Anxiety, Personality Traits, and Psychological Dissociation in Patients with Temporal Lobe Epilepsy (TLE) and Extra-TLE

PURPOSE

This study was performed to investigate the relation between symptoms of interictal depression, anxiety, personality traits, and psychological dissociation with the localization and lateralization of the epileptogenic zone in patients with partial epilepsy.

METHODS

All patients were diagnosed according to the localization-related concept of the 1989 International League Against Epilepsy (ILAE) Classification of Epilepsies and Epileptic Syndromes, and the localization and lateralization of the epileptogenic zone was established by using the clinical criteria for noninvasive presurgical evaluation. This resulted in 67 patients with temporal lobe epilepsy (TLE) and 64 patients with extra-TLE. All patients were assessed on the various aspects of psychopathology by using a comprehensive battery of standardized diagnostic instruments.

RESULTS

We did not find the hypothesized excess of psychiatric symptoms in patients with (mesial) TLE in comparison with patients with extra-TLE. We also found no differences between patients with the lateralization of epilepsy in the left versus the right hemisphere.

CONCLUSIONS

TLE per se cannot be considered a risk factor in developing more or more severe symptoms of psychopathology in patients with partial epilepsy. Concomitant factors, such as the duration of epilepsy, seizure frequency, and frontal lobe dysfunction may play an additional role. Our findings support the hypothesis of a multifactorial explanation for the psychiatric symptoms in patients with epilepsy.

Factors associated with generic and disease-specific quality of life in temporal lobe epilepsy

PURPOSE

We aimed at further elucidating the association between quality of life (QOL) and sociodemographic factors, clinical seizure factors, depression and anxiety in drug-resistant temporal lobe epilepsy (TLE).

METHODS

We studied 106 consecutive adult right-handed patients (mean age 35.4 +/- 9.7; 50% males; IQ> or = 70) with drug-resistant unilateral (59% right) TLE (70% hippocampal sclerosis, 30% tumors or other lesions), who underwent a comprehensive non-invasive pre-surgical protocol. They completed the Beck Depression Inventory (BDI) and the State Form of the Spielberger State-Trait Anxiety Inventory (STAI). To measure QOL, we used both a generic instrument, the WHOQOL-100, and a disease-specific instrument, the 31-item quality of life in epilepsy (QOLIE-31). Multiple linear regression analysis was used to examine the relationship between each QOL domain and age, gender, education, side of TLE, duration of epilepsy, seizure frequency, and level of depression and anxiety.

RESULTS

Severity of depressive symptoms was significantly associated with lower scores across most QOL domains. Depression was consistently the strongest predictor of lower scores on almost all QOL domains. Also, severity of anxiety symptoms was significantly associated with lower scores across many QOL domains. Independent significant relationships between QOL and sociodemographic or clinical epilepsy variables were limited in number and strength.

CONCLUSIONS

Our findings suggest that QOL in TLE might be substantially affected by the presence and severity of depressive symptoms and, to a lesser degree, of anxiety symptoms. While clinical seizure variables had a weaker association with QOL, the absence of seizure-free patients might have obscured a relation between seizure frequency and QOL. Healthcare professionals should be aware of the significance of patients' emotional state and of the role it plays for their QOL. Adopting a biopsychosocial approach might be useful to address patients' needs.

Risk factors for depression in patients with epilepsy

PURPOSE

Symptoms of depression are present in 40 to 60 percent of patients with epilepsy. Prior research indicated significant correlation between the incidence and frequency of focal seizures and clinical depression, especially in patients with temporal lobe epilepsy. Anticonvulsive drugs and psychosocial factors contribute to the occurrence of depression as well. The aim of the study was to determine the major depression risk factors in patients with epilepsy.

METHODS

The research was conducted on 203 patients with epilepsy (117 females and 86 males), aged 18 to 50 years, with total time of illness ranging from 60 to 580 months. All subjects underwent the same research protocol, which was applied interictally. Interictal depression was diagnosed according to ICD-10 diagnostic criteria for affective and delusional disorders. The diagnosis was supported by Beck Depression Inventory (BDI), Hamilton Depression Rating Scale (HAM-D) and Montgomery-Asberg Depression Rating Scale (MADRS). Statistical analysis included chi2 test, Fisher's exact test and stepwise logical regression model analysis.

RESULTS

In our study 100 patients with epilepsy out of 203 suffered from concurrent depression (49.2%); 76 of them had severe depression (37.4%) and 24 patients had mild depression (11.8%). Complex partial seizures and absence of secondary generalized tonic-clonic seizures were found to be the risk factors for depression. Treatment with clonazepam, frequent hospitalizations (drug-resistancy) and lack of occupational activity were revealed to be additional significant contributing factors.

CONCLUSIONS

Depression in patients with epilepsy is a serious medical and social problem since it afflicts almost one half of all patients treated in epilepsy referral centers. It seems to be correlated with certain types of epileptic seizures, with high frequency of seizures, sub-optimal pharmacologic treatment and lack of occupational and social activity.

Depression and neurological disorders

PURPOSE OF REVIEW

Clinical studies support a bidirectional link between depression and neurological diseases. Here we review the most recent findings supporting the hypothesis that major depression is a medical illness of the brain which can be elicited by neurological illnesses.

RECENT FINDINGS

In the last year major improvements in brain-imaging techniques allowed correlations to be demonstrated between functional and structural brain abnormalities in specific brain areas (prefrontal cortex, hippocampus, cingulate gyrus) and the presence and severity of affective disorders, thus suggesting a neural basis for their onset and progression. Similar lesions, caused by neurological diseases, have been found to correlate with the presence of depression in neurological illnesses, but literature on the topic is still lacking. Depression in neurological disorders responds to the same treatments available for idiopathic major depression, but patients seem to have different sensitivities to side effects depending on their specific neurological syndrome. Most available data come from case reports and open trials.

SUMMARY

'Psychiatric' and 'neurologic' depression seem to share common abnormalities in specific brain areas, but sound brain-imaging studies of the neural correlates of depression in neurological disorders are still lacking. Available treatments are efficacious, but no clear-cut guidelines about the best drugs and dosages can be defined because double-blind placebo-controlled studies are still scarce.

Neuropsychological differences in epileptic patients with seizures of frontal and temporal lobe origin

This investigation studied the neuropsychological differences in nonsurgical cryptogenic epileptic patients with seizures of frontal and temporal lobe origin, which were classified according to clinical criteria. Fifty-one patients with partial seizures of frontal (n = 15) or temporal (n = 36) lobe origin and 2 matched control groups were administered a battery of neuropsychological tests assessing intelligence, memory, perceptual, and frontal functions. Patients with seizures of temporal lobe onset performed worse than patients with seizures of frontal lobe origin, even in frontal functions. The findings of this study corroborate the low specificity of tasks regarded as frontal lobe tests and the difficulty in detecting frontal lobe neuropsychological focalities.

Depression and Mania in Patients with Epilepsy

Depression has a major impact on quality of life in patients with epilepsy and is also the main risk factor for the increased suicide rate in epilepsy. The frequency of depressive disorders depends on the severity of epilepsy and the localization of the epileptogenic focus, with a prevalence of <or=50% in patients with intractable temporal lobe epilepsy. The diagnosis of depression in epilepsy may be difficult because symptoms of depression may be fluctuating, and some symptoms, such as memory complaints, may be misinterpreted as being a consequence of drug treatment or the epilepsy per se. Affective disorders in epilepsy may differ from those seen in patients without epilepsy. A possibility exists that patients with epilepsy will develop a specific interictal dysphoric syndrome related to limbic system dysfunction. Recent epidemiologic studies suggest a bidirectional relation between depression and epilepsy. Depression does not necessarily occur after the onset of epilepsy; the sequence may as well be the other way round, suggesting a common underlying mechanism for both disorders. Classic bipolar disorder type I is rarely seen in epilepsy, and manic episodes occur almost exclusively in the setting of postictal psychosis or after epilepsy surgery. This article explores the clinical manifestations of depressive and manic disorders in epilepsy and the differences from bipolar disorder.

Depression and suicide attempt as risk factors for incident unprovoked seizures

Major depression has been shown to increase the risk for development of epilepsy, but prior studies have not evaluated whether this is due to specific symptoms of depression. We conducted a population-based case-control study of all newly diagnosed unprovoked seizures among Icelandic children and adults aged 10 years and older to test the hypothesis that major depression is a risk factor for developing unprovoked seizure and epilepsy, and to address whether specific symptoms of depression account for this increased risk. Cases were matched to the next two same sex births from the population registry. Using standardized interviews, we ascertained symptoms of major depression to make a Diagnostic and Statistical Manual, Fourth Edition (DSM-IV) diagnosis. A history of major depression was 1.7-fold more common among cases than among controls (95% confidence interval, 1.1-2.7). A history of attempted suicide was 5.1-fold more common among cases than among controls (95% confidence interval, 2.2-11.5). Attempted suicide increased seizure risk even after adjusting for age, sex, cumulative alcohol intake, and major depression or number of symptoms of depression. Major depression and attempted suicide independently increase the risk for unprovoked seizure. These data suggest that depression and suicide attempt may be due to different underlying neurochemical pathways, each of which is important in the development of epilepsy.

Depressed mood and memory impairment in temporal lobe epilepsy as a function of focus lateralization and localization

OBJECTIVE

Memory disorders and depressed mood are prominent psychological symptoms of temporal lobe epilepsies (TLEs). We examined the interaction of depressive mood and memory as a function of focus localization.

METHODS

One hundred fifty-two TLE patients with right mesial (n=37, RTLE-AHS), right lateral (n=31, RTLE-LAT), left mesial (n=42, LTLE-AHS), and left lateral (n=42, LTLE-LAT) lesions and epilepsies underwent comprehensive presurgical evaluation and neuropsychological assessment of mood and memory. Univariate and multivariate analyses of covariance (ANCOVAs) and partial correlation analyses were performed to reveal interactions of depression and memory as a function of focus localization.

RESULTS

No differences between the study groups were revealed for depression, indicating a general risk of 30% for depressed mood (BDI>12) in patients with TLE. ANCOVAs revealed significant main effects of focus side (left: verbal learning deficits; right: figural learning deficits) and site (mesial at disadvantage) on learning and memory scores. Correlation analyses revealed interactions between memory and mood only in LTLE-LAT patients.

CONCLUSIONS

Although the data provide evidence that side and site of the epileptogenic region differentially affect material specific memory performance, there was no evidence of a specific temporal target region for depressive mood. In the majority of the patients, depressed mood and memory impairment appeared as independent rather than as related symptoms of TLE. In LTLE-LAT, however, mood was significantly related to verbal and figural memory performance. Epilepsy-driven pathological left temporofrontal circuits are discussed as a prerequisite for the coupling of mood disorders and memory impairment in this specific patient subgroup which is also known from the psychiatric major depression syndrome.

Depression in epilepsy: a frequently neglected multifaceted disorder

Depressive disorders (DDs) are frequent psychiatric comorbidities of neurological disorders like multiple sclerosis, stroke, dementia, migraine, Parkinson's disease, and epilepsy. The clinical manifestations of DDs in these neurological disorders are identical to those of idiopathic mood disorders. In epilepsy, however, DDs can frequently also present with clinical characteristics that differ from those of idiopathic depression and fail to meet the criteria included in the Diagnostic and Statistical Manual of Psychiatric Disorders-Fourth Edition. Despite their multifaceted clinical expressions and their relatively high prevalence in epilepsy, DDs very often go unrecognized and untreated. The aim of this article is to review some of the more relevant aspects of DDs in epilepsy, to highlight their various clinical expressions, and their impact on the quality of life of patients with epilepsy, and to review the basic principles of treatment.

Depression in children and adolescents with epilepsy

Depression in children and adolescents with epilepsy is a common but often unrecognized disorder. Both epilepsy and depression are characterized by a chronic course and poor long-term psychosocial outcome. The risk of suicide is even greater in depressed youth with epilepsy than in the general youth population. Educating parents about mood disorders may allow them to be more receptive to psychiatric treatment for their child or themselves. Epidemiological and clinical data on depression in children/adolescents with epilepsy are presented. Seizure-related and general risk factors for the development of depression in youth with epilepsy are reviewed. General guidelines for diagnosis and treatment of depression in children and adolescents are discussed. The early identification and treatment of childhood-onset depression is an important clinical task for all pediatric specialists. Safe and effective multimodal treatment approaches are available.

Depression in epilepsy: prevalence, clinical semiology, pathogenic mechanisms, and treatment

Depression is the most frequent comorbid psychiatric disorder in epilepsy. Its lifetime prevalence has been estimated at between 6% and 30% in population-based studies and up to 50% among patients followed in tertiary centers. The risk of suicide has been estimated to be 10 times higher than that in the general population. Although no one questions that epilepsy is a risk for depression, recent studies have also revealed that a history of depression is associated with a 4- to 6-fold greater risk of developing epilepsy. These data suggest either a possible "bi-directional" relationship between these two disorders or the presence of common pathogenic mechanisms that facilitate the occurrence of one in the presence of the other. The clinical presentation of depressive disorders in epilepsy can be identical to that of nonepileptic patients and can include major depression, bipolar and dysthymic disorders, and minor depression. In a significant percentage of cases, however, the clinical features of depression in epilepsy fail to meet any of the DSM-IV Axis I categories. Depression in epilepsy may be iatrogenically induced with various antiepileptic drugs used to treat the seizure disorder or after surgical treatment of intractable epilepsy. Despite its relatively high prevalence, depression remains unrecognized and untreated, and unfortunately its treatment is based on empirical and uncontrolled data.

Mood disorders in patients with epilepsy: epidemiology and management

Patients with epilepsy are at high risk for depression because of an incompletely understood combination of factors that may be both psychosocial and neurological. Interictal depression in patients with epilepsy is an undertreated condition, in part because of concern regarding drug interactions and the risk of exacerbating seizures with antidepressant treatment. Bipolar disorder is not described as occurring with a higher than expected frequency in the population with epilepsy, but high rates of depression and suicide are well recognised, highlighting the need for more emphasis on antidepressive treatment in this group of at-risk patients. Neurological factors, including site and lateralisation of seizure focus, may be important for the development of depression, with left-sided seizure foci having a higher association with depressive symptoms. Forced normalisation may be a factor in the paradoxical onset of depression in patients with epilepsy whose seizures suddenly become well controlled by anti-seizure treatment. Lowering of folic acid levels by some antiepileptic drugs (AEDs) may also influence the expression of depression in patients with epilepsy. New AEDs continue to emerge as beneficial treatments themselves for mood disorders, with lamotrigine, gabapentin and, to a lesser extent, topiramate having clinical trials data to support their use in patients with bipolar disease. Similar positive data are available for vagal nerve stimulation. Mood effects of AEDs can be complicated, however, as many of these drugs (e.g. tiagabine) have also been reported to cause depression as an adverse effect. Electroconvulsive therapy in depressed patients with epilepsy requires special consideration. The selective serotonin reuptake inhibitors (SSRIs) and antidepressants that act at multiple receptors (e.g. nefazodone, venlafaxine) are the most appropriate treatments for depressed patients with epilepsy. Among these agents, citalopram has a low risk of interactions with AEDs. Bupropion, clomipramine and maprotiline are associated with a greater risk of seizures compared with other antidepressants and consequently should be used with caution in the treatment of depression in patients with epilepsy.

Risk factors for suicide in epilepsy: a case control study

PURPOSE

Suicide is considered to be one of the most important causes of death contributing to the increased mortality of persons with epilepsy. We investigated the association between the risk of suicide in persons with epilepsy and clinical factors that might increase or have been suggested to increase the risk of suicide.

METHODS

A case-control study was nested within a cohort of 6,880 patients registered in the Stockholm County In-Patient Register with a diagnosis of epilepsy. The study population was followed up through the National Cause of Death Register. Twenty-six cases of suicide, 23 cases of suspected but not proven suicide, and 171 controls, living epilepsy patients, were selected from the cohort. Clinical data were collected through medical record review.

RESULTS

There was a ninefold increase in risk of suicide with mental illness and a 10-fold increase in relative risk (RR) with the use of antipsychotic drugs. The estimated RR of suicide was 16.0 [95% confidence interval (CI), 4.4-58.3] for onset of epilepsy at younger than 18 years, compared with onset after 29 years. The risk of suicide seemed to increase with high seizure frequency and antiepileptic drug (AED) polytherapy, although the estimates were imprecise and the associations not statistically significant. Insufficient data on seizure frequency and changes in AED dosage due to incomplete case records were associated with high RRs. We found no association between risk of suicide and any particular AED, with type of epilepsy, or localization or lateralization of epileptogenic focus on EEG [RR = 0.3 (95% CI, 0.1-1.7)].

CONCLUSIONS

The profile of the epilepsy patient who commits suicide that emerges from our study is a patient with early onset (particularly onset during adolescence) but not necessarily severe epilepsy, psychiatric illness, and perhaps inadequate neurologic follow-up. Previous reports of an association with temporal lobe epilepsy could not be confirmed.