Neuropsychological profile of mild temporal lobe epilepsy

Contribution of the Brown Location Test to the pre-surgical neuropsychological assessment of temporal lobe epilepsy

The nature of memory deficits in mesial temporal lobe epilepsy (mTLE) can depend on the side of the epileptogenic zone (EZ). Although left mTLE has been consistently associated with impairments in verbal memory, the association between right mTLE and non-verbal memory is less clear, which may be attributable to methodological limitations of existing visuospatial memory tests (e.g., possible use of verbalization strategies, involvement of psychomotor or visuospatial skills, task structure which differs between verbal and non-verbal memory tests). The Brown Location Test (BLT) was developed to evaluate visuospatial memory by addressing such limitations, and displays a good potential value for lateralizing the EZ. To our knowledge, no independent study has been conducted to assess the contribution of the BLT in lateralizing and localizing the EZ among patients undergoing pre-surgical assessment for drug-resistant focal epilepsy. This study aims to do so by comparing visuospatial and verbal memory performance of patients according to EZ lateralization (left vs. right) and localization (mesiotemporal vs. non-mesiotemporal). Eighty-nine adult patients with TLE were divided into four groups based on EZ (left mTLE, right mTLE, left non-mTLE, right non-mTLE) and were administered the BLT and the Rey Auditory Verbal Learning Test (RAVLT) pre-operatively. Memory performance was associated with sex, education and number of antiseizure medications. Only delayed recognition hits on the RAVLT showed the expected material-specific impairment associated with left mTLE, whereas BLT performance did not differ between groups. Therefore, caution is required when interpreting material-specific memory performances to localize and lateralize the EZ among patients undergoing pre-surgical assessment for drug-resistant epilepsy.

Prospective memory is associated with aspects of disability and quality of life in people with epilepsy

INTRODUCTION

Episodic memory disruptions in epilepsy stem from shared neurocircuitry. While prior research has focused on retrospective memory (RM), prospective memory (PM; i.e. remembering to remember) also deserves consideration given its critical role in the management of daily activities. The current investigation assessed whether PM is associated with disability and quality of life in people with epilepsy.

METHODS

This cross-sectional, correlational study included a consecutive series of 50 people with epilepsy presenting for neuropsychological evaluation who completed the Royal Prince Alfred Prospective Memory Test (RPA) and Prospective and Retrospective Memory Questionnaire (PRMQ) and 63 demographically comparable healthy adults. The participants with epilepsy also completed clinical measures of neuropsychological ability and questionnaires assessing disability and quality of life.

RESULTS

People with epilepsy had significantly more frequent memory symptoms as compared to healthy adults at a very large effect size. Worse mood was associated with lower PM ability at a medium effect size and more frequent PM symptoms at a large effect size. A hierarchical linear regression indicated that PM explained 52% of the variance in disability and 43% of the variance in quality of life after accounting for RM ability.

CONCLUSIONS

PM is associated with poorer everyday functioning among people with epilepsy and shows evidence of incremental value beyond RM ability in that regard. Future studies are needed to understand the complex pathways from PM to functional limitations to inform clinical intervention.

Impaired interhemispheric synchrony and effective connectivity in right temporal lobe epilepsy

BACKGROUND

The brain functional network plays a crucial role in cognitive impairment in temporal lobe epilepsy (TLE). Based on voxel-mirrored homotopic connectivity (VMHC), this study explored how directed functional connectivity changes and is associated with impaired cognition in right TLE (rTLE).

METHODS

Twenty-seven patients with rTLE and twenty-seven healthy controls were included to perform VMHC and Granger causality analysis (GCA). Correlation analysis was performed based on GCA and cognitive function.

RESULTS

Bilateral middle frontal gyrus (MFG), middle temporal gyrus, dorsolateral superior frontal gyrus (SFGdor), and supramarginal gyrus (SMG) exhibited decreased VMHC values in the rTLE group. Brain regions with altered VMHC had abnormal directed functional connectivity with multiple brain regions, mainly belonging to the default mode network, sensorimotor network, and visual network. Besides, the Montreal Cognitive Assessment (MoCA) score was positively correlated with the connectivity from the left SFGdor to the right cerebellum crus2 and was negatively correlated with the connectivity from the left SMG to the right supplementary motor area (SMA) before correction. Before correction, both phasic and intrinsic alertness reaction time were positively correlated with the connectivity from the left MFG to the left precentral gyrus (PreCG), connectivity from the left SMG to the right PreCG, and the connectivity from the left SMG to the right SMA. The executive control effect reaction time was positively correlated with the connectivity from the left MFG to the left calcarine fissure surrounding cortex before correction.

CONCLUSION

The disordered functional network tended to be correlated with cognition impairment in rTLE.

The validity and reliability of the Test of Memory Strategies among Italian healthy adults

Background

Previous literature has shown that executive functions (EF) are related to performance in memory (M) tasks. Nevertheless, there is a shortage of psychometric tests that examine these two constructs simultaneously. The Test of Memory Strategies (TMS; previously validated in Spain and Portugal) could be a useful verbal learning task that evaluates these two constructs at once. In this study, we aimed to evaluate the psychometric properties of the TMS in an Italian adult sample.

Method

One hundred twenty-one healthy volunteers (74 F, Mean age = 45.9 years old, SD = 20.4) who underwent a neuropsychological examination participated in this study. We conducted a Confirmatory factor analysis (CFA) to evaluate the structural validity of the TMS. We conducted a latent variable analysis to examine convergent and discriminant validity of the TMS sub-scale scores reflecting executive functions and memory. We also examined the TMS reliability in terms of internal consistency through the McDonald's omega.

Results

The CFA confirmed the expectation that the TMS-1 and TMS-2 subtests reflect a factor and that the TMS-3, TMS-4, and TMS-5 subtests reflect a different factor. This result is in line with the prediction that TMS-1 and TMS-2 require the use of executive functions and memory simultaneously, and therefore we called this factor executive functions (EF); whereas the TMS-3, TMS-4, and TMS-5 subtests require less involvement of executive functions, thus reflecting a construct that we named memory (M). The TMS subtests for EF and M showed convergent validity with the test scores using a traditional neuropsychological battery, assessing memory and executive functions separately. Finally, the reliability of the subtests was good.

Conclusions

These preliminary findings suggest that TMS is a valid and reliable scale to simultaneously assess M and EF while among Italian healthy adults.

Distinct limbic connectivity in left and right benign mesial temporal lobe epilepsy: Evidence from a resting state functional MRI study

Background

Functional connectivity (FC) studies showed that pharmaco-resistant mesial temporal lobe epilepsy (MTLE) affects not only the limbic system, but also several extra-limbic regions, including areas belonging to resting state networks. Less is known about FC in subjects with benign MTLE (i.e., sensitive to antiseizure medication, bMTLE).

Aim and methods

We evaluated FC of hippocampus and amygdala in subjects with bMTLE, distinguished based on the epileptic focus lateralization. We enrolled 19 patients (10 with left and 9 with right bMTLE) and 10 age-matched healthy subjects. Connectivity was investigated at rest by using a seed-based regression analyses approach with four regions of interest (left and right hippocampus, left and right amygdala). Patients were also tested with a neuropsychological battery and their scores were correlated with fMRI data.

Results and conclusions

Our study documented an asymmetrical disruption of FC in bMTLE, in relation to the side of the focus. Right subjects only exhibited limited altered connections, while left subjects—who performed worse in verbal memory tests—showed a wide bilateral hypoconnectivity of hippocampus and amygdala with areas belonging to language and memory network. The strength of FC between left limbic areas and language and memory network correlated with better performances in verbal memory tests. Moreover, we observed an increased FC with areas of default mode network, more pronounced in left subjects, a possible attempt to compensate cognitive deficit but without effectiveness.

We believe that these findings could help to better characterize bMTLE, in which a dysfunction of limbic connectivity is detectable despite well-controlled epilepsy.

Psychogenic nonepileptic seizures: The effect of accurate diagnosis on cognition

OBJECTIVE

Much remains to be elucidated about the cognitive profile of patients with psychogenic nonepileptic seizures (PNES) and about how this changes over time and compares to that of patients with epilepsy. The aim of this study was to study the neuropsychological profile of patients with PNES and an age-matched group of patients with temporal lobe epilepsy (TLE) during admission to a video electroencephalography monitoring unit (VEMU) and 1 year after discharge.

METHODS

Patients diagnosed with PNES or TLE at a VEMU were prospectively recruited. Neuropsychological, demographic, clinical, and treatment variables were collected at baseline and 1 year. To minimize multiple comparisons, scores from different cognitive tests were computed for attention and psychomotor speed, verbal memory, visual memory, language, and executive function. A global cognitive impairment index (GCII) was also created. Post hoc analyses were conducted to identify clinical variables that might mediate the differences observed in cognition over time between the groups. These included seizure frequency, number of antiseizure medication (ASM), number of psychotropic drugs, depression, and quality of life.

RESULTS

We studied 24 patients with PNES and 24 patients with TLE. The groups performed similarly in the baseline neuropsychological tests. There was a significant time (baseline to 1-year follow-up) by group (PNES vs TLE) interaction for the GCII (p = 0.006), language (p = 0.04), and executive function (p = 0.013), with PNES patients showing improvement and TLE patients remaining stable. The time by group interaction for attention and psychomotor speed showed a trend toward significance (p = 0.056), Reduction in number of ASM was associated with improved cognition in PNES patients at 1 year.

CONCLUSION

PNES patients showed improved cognition at 1 year of follow-up, particularly in language and executive functions. This finding shows the potential benefits of an early, accurate diagnosis, which range from improved cognition to better management.

Neuropsychological assessment could distinguish among different clinical phenotypes of progressive supranuclear palsy: A Machine Learning approach

Progressive supranuclear palsy (PSP) is a rare, rapidly progressive neurodegenerative disease. Richardson's syndrome (PSP-RS) and predominant parkinsonism (PSP-P) are characterized by wide range of cognitive and behavioural disturbances, but these variants show similar cognitive pattern of alterations, leading difficult differential diagnosis. For this reason, we explored with an Artificial Intelligence approach, whether cognitive impairment could differentiate the phenotypes. Forty Parkinson's disease (PD) patients, 25 PSP-P, 40 PSP-RS, and 34 controls were enrolled following the consensus criteria diagnosis. Participants were evaluated with neuropsychological battery for cognitive domains. Random Forest models were used for exploring the discriminant power of the cognitive tests in distinguishing among the four groups. The classifiers for distinguishing diseases from controls reached high accuracies (86% for PD, 95% for PSP-P, 99% for PSP-RS). Regarding the differential diagnosis, PD was discriminated from PSP-P with 91% (important variables: HAMA, MMSE, JLO, RAVLT_I, BDI-II) and from PSP-RS with 92% (important variables: COWAT, JLO, FAB). PSP-P was distinguished from PSP-RS with 84% (important variables: JLO, WCFST, RAVLT_I, Digit span_F). This study revealed that PSP-P, PSP-RS and PD had peculiar cognitive deficits compared with healthy subjects, from which they were discriminated with optimal accuracies. Moreover, high accuracies were reached also in differential diagnosis. Most importantly, Machine Learning resulted to be useful to the clinical neuropsychologist in choosing the most appropriate neuropsychological tests for the cognitive evaluation of PSP patients.

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.

Alteration of GABAergic signaling is associated with anxiety-like behavior in temporal lobe epilepsy mice

Temporal lobe epilepsy (TLE), which is one of the most common neurological diseases, is accompanied by a high incidence of psychiatric disorders. Among these psychiatric disorders, anxiety is one of the major psychiatric comorbidities in epilepsy patients. However, anxiety in epilepsy patients often remains unrecognized and untreated. It is believed that the inhibitory networks of γ-aminobutyric acid (GABA) neurotransmission play pivotal roles in the modulation of emotion and mood responses in both physiological and pathological conditions. The impairment of neurotransmission mediated by GABAergic signaling is related to the pathophysiology of anxiety. However, it remains unclear whether and how GABAergic signaling modulates anxiety responses in the context of an epileptic brain. In the present study, we sought to determine the role of inhibitory networks of GABAergic signaling in the anxiety-like behavior of epileptic mice. Our results show epileptic mice exhibited increased anxiety-like behavior, and this increased anxiety-like behavior was accompanied by a decrease in GABAergic interneurons and an increase in GABA type A receptor (GABA_AR) β3 subunit (GABRB3) expression in the hippocampus. Furthermore, the activation of GABA_ARs produced an anxiolytic-like effect, while the inhibition of GABA_ARs elicited an anxiogenic-like effect in the epileptic mice, suggesting that the alteration of GABAergic signaling is associated with anxiety-like behavior in epileptic mice. Thus, targeting GABAergic signaling in the epileptic brain may provide an effective anxiolytic treatment in epilepsy patients.