Epilepsy and intelligence. I. Intellectual status in a group of 215 ambulatory patients]

A group of 119 men and 96 women, mean age 32.8 years, with a mean onset of the disease at the age 13 years was examined by Wechsler's intelligence test for adults (Wechsler-Bellevue). They assessed the mean intellectual level, total IQ mean = 104.4, s = 15.3. The intellectual performance of female patients had roughly a normal distribution, in men it was shifted slightly to higher zones. The mean absolute difference of the verbal IQ and performance IQ was mean = 8.4, s = 7.0, median = 7. The results are consistent with some more recent data in the literature on good intellectual abilities of the majority of epileptic subjects. The authors discuss the causes of frequent erroneous ideas of laymen and health professionals on an association of epilepsy and intellectual inadequacy. Among others there persists prejudice, problems of patients as regards memory, problems in the psychosocial sphere, psychopathological manifestations, adverse side-effects of drugs, sequelae of transient impairment of consciousness manifested clinically by short-term reduced performance. Real impairment of epileptic patients are assessed best by special neuropsychological methods, however, evaluation of intellectual abilities is necessary.     

Analysis of functional hemispheric asymmetry in children with partial epilepsy and normal IQ by performance in WISC subtests]

We studied 87 normal IQ children, 26 partial epileptic (epileptic group) and 61 non-epileptic children (control group) with mean age of 9 years in relation to cognitive performance in Wechsler Infant Scale for Children (WISC) battery. The epileptic group showed lower score in IQ performance and in three verbal subtests (Information, Digit span, Arithmetic) and three performance subtests (Block Design, Object Assembly and Coding). Patients with right hemisphere EEG focus showed low score in subtests related to spatial ability and non-verbal attention, whereas patients with left hemisphere EEG focus showed low score only in Digit span subtest (related to immediate memory and verbal attention). The authors suggest that cognitive deficits in partial non-lesional epileptic children is related to the side of EEG interictal abnormalities, even in children with normal IQ.     

Evidence for an Association between Brain-Derived Neurotrophic Factor Val66Met Gene Polymorphism and General Intellectual Ability in Early-Onset Schizophrenia

Background: Brain-derived neurotrophic factor (BDNF) plays a crucial role in the survival, development and maintenance of neuronal systems, and the Val66Met polymorphism has been implicated in memory functions. Method: We examined the association of BDNF with general intellectual ability in 161 individuals including 53 early-onset patients with schizophrenia (EOS), 91 healthy biological relatives, and 17 relatives with major depressive disorder (MDD), using the Wechsler Intelligence Scales (WISC). Results: Regardless of diagnosis, individuals with the Met66 allele had a significantly higher performance score than those homozygous for Val66 on vocabulary, block design and object assembly subtests of the WISC. EOS probands showed poor performance on all IQ subtests compared with relatives with and without MDD. Limitations: Relatively smaller sample size of individual genotypes. Conclusions: BDNF genotype may play a role in specific cognitive functions and dimensions of intelligence. The Met allele appears to be associated with superior performance in IQ compared with relatives Val/Val genotype.     

IQ stabilization in childhood-onset schizophrenia

OBJECTIVE: To examine the long term IQ trajectory for childhood-onset schizophrenia (COS) in an expanded, prospective longitudinal study. METHODS: Seventy children meeting DSM criteria for schizophrenia were tested at 2 year intervals with age appropriate Wechsler intelligence tests and repeated administration of information and comprehension WISC subtests even after age 18. For a subgroup with 31 patients, pre-NIH IQ test administrations were available including 18 pre-psychotic and 13 post-psychotic subjects. The pattern of IQ performance over time was determined using mixed model regression analysis. RESULTS: No progressive cognitive decline was seen up to 13+ years post psychosis onset. For the subgroup of subjects with pre-illness scores, there had been an initial steep decline in IQ, from about 2 years prior to 1.7 years after onset of psychotic symptoms, as reported for adult patients. CONCLUSIONS: The level long-term trajectory of IQ measures in COS appears stable, similar to that reported for adult onset patients. For COS, level cognitive functioning extends up to 13+ years post psychosis onset, in spite of chronic illness and concomitant, progressive loss of cortical gray matter.     

Progressive intellectual impairment in children with Encephalopathy related to Status Epilepticus during slow Sleep

We investigated whether Encephalopathy related to Status Epilepticus during slow Sleep (ESES) in childhood was associated with progressive intellectual decline. Participants were identified from the caseload of a single paediatric neurosciences centre and EEG department. A retrospective review of overnight sleep EEG reports (n=2200) over a five‐year period identified twenty‐two children as having the neurophysiological characteristics of ESES. All had repeat neuropsychological assessment using the WISC‐III (UK) and/or WPPSI‐R (UK). There was a statistically significant reduction in Full‐Scale IQ and Performance IQ across a mean and median time interval of two years. Around a third of the participants showed a clinically significant regression in intellectual functioning evidenced by =>12‐point reduction in IQ. These patients were not distinguishable from the rest of the cohort in terms of clinical history, imaging or duration of ESES. The reduction in IQ reflected reduced processing speed, working memory and overall cognitive efficiency. Children with a history of ESES require close monitoring in order to support educational planning and provide families with accurate information about prognosis.     

Neurocognitive consequences of a paediatric brain tumour and its treatment: a meta‐analysis

Aim This meta‐analysis provides a systematic review of studies into intellectual and attentional functioning of paediatric brain tumour survivors (PBTS) as assessed by two widely used measures: the Wechsler Intelligence Scale for Children (3rd edition; WISC‐III) and the Conners’ Continuous Performance Test (CPT). Method Studies were located that reported on performance of PBTS (age range 6–16y). Meta‐analytic effect sizes were calculated for Full‐scale IQ, Performance IQ, and Verbal IQ as measured by the WISC‐III, and mean hit reaction time, errors of omission, and errors of commission as measured by the CPT. Exploratory analyses investigated the possible impacts of treatment mode, tumour location, age at diagnosis, and time since diagnosis on intelligence. Results Twenty‐nine studies were included: 22 reported on the WISC‐III in 710 PBTS and seven on CPT results in 372 PBTS. PBTS performed below average (p_s<0.001) on Full‐scale IQ (Cohen’s d=?0.79), Performance IQ (d=?0.90), and Verbal IQ (d=?0.54). PBTS committed more errors of omission than the norm (d=0.82, p<0.001); no differences were found for mean hit reaction time and errors of commission. Cranial radiotherapy, chemotherapy, and longer time since diagnosis were associated with lower WISC‐III scores (p_s<0.05). Interpretation PBTS have seriously impaired intellectual functioning and attentiveness. Being treated with cranial radiotherapy and/or chemotherapy as well as longer time since diagnosis leads to worse intellectual functioning.     

Sex differences in performance over 7 years on the Wechsler Intelligence Scale for Children – Revised among adults with intellectual disability

Background The aim of this study was to explore changes related to sex differences on the Wechsler Intelligence Scale for Children – Revised (WISC‐R) subtest performance over a 7‐year interval in middle‐aged adults with intellectual disability (ID). Cognitive sex differences have been extensively studied in the general population, but there are few reports concerning individuals with ID. Sex differences are of current relevance to actively debated issues such as cognitive changes during menopause and risk for Alzheimer's disease. Given that hormonal effects on cognition have been observed in the general population, particularly in areas such as visuospatial processing, and individuals with Down's syndrome (DS) have been reported to be hormonally and reproductively atypical, we analysed our data to allow for the possibility of an aetiology‐specific profile of sex differences for these adults. Methods The WISC‐R subtests were administered in a longitudinal study, as part of a more comprehensive test battery, at least twice within 7 years. Participants were 18 females with ID without DS [age at first test time (time 1): mean = 40.5; IQ: mean = 59.3], 10 males with ID without DS (age at time 1: mean = 42.4; IQ: mean = 59.4), 21 females with DS (age at time 1: mean = 37.9; IQ: mean = 51.6), and 21 males with DS (age at time 1: mean = 40.3; IQ: mean = 54.3). All participants were in the mild to moderate range of ID and were displaying no changes suggestive of early dementia. Results Females, regardless of aetiology of ID, exhibited a robust superiority on the coding subtest, which parallels the widely reported difference among adults in the general population. Additionally, there was a decline in overall performance during the 7‐year study interval, particularly on the verbal subscale subtests, but there was no evidence of sex‐differentiated decline. There were also marginal sex by aetiology interactions on the object assembly and block design subtests, suggesting that males with unspecified ID might perform better than their female peers, but among adults with DS, females might do better than males. Conclusions This study supports the presence of cognitive sex differences in the population with ID as indicated by female superiority on the WISC‐R coding subtest. Extending this observation to adults with ID has implications for explanations of female advantage on this task, which now have to account for its presence among individuals with a broader range of intellectual capabilities, more atypical developmental histories and more varied genotypes than previously considered. Trends towards sex by aetiology interactions on the two visuoconstructive subtests, while marginal, were sufficient to warrant continued consideration of the idea of a distinct profile of sex differences for adults with DS and to justify looking at the effects of sex separately within different aetiologies of ID.     

Intelligence in epilepsy: a prospective study in children

A prospective study tested the stability of the IQ in children with seizure disorders. Seventy-two children with epilepsy underwent psychological evaluations within two weeks of initial diagnosis and yearly thereafter for an average of 4 years. Forty-five of the patients also had a nonepileptic sib evaluated in parallel. The mean IQ for all the children with epilepsy was 99.7 (+/- 20.2, standard deviation) at the time of the initial test, not significantly different from the siblings. This score did not change appreciably with time. Eight of the 72 epileptic patients (11.1%), however, had a persistent decrease in IQ of 10 points or more. These patients had a higher incidence of drug levels in the toxic range (p less than 0.001), their epilepsy was more difficult to control (p less 0.005), and their seizures began at an earlier age (p less than 0.05). Discriminant analysis is revealed that the number of drugs to which the patient became toxic and the age at seizure onset were the two best predictors of ultimate IQ. These two predictors correctly classified 71% of all patients as to whether their IQ would drop by 10 or more points during the test period, remain within 10 points of the initial test score, or increase by more than 10 points. Total number of seizures and seizure control were less good predictors, according to this method of analysis. The findings suggest that, in younger children in particular, total seizure control should not be achieved at the price of repeated episodes of drug toxicity.     

Outcome after hemispherectomy in hemiplegic adult patients with refractory epilepsy associated with early middle cerebral artery infarcts

Purpose:   To study the outcome after hemispherectomy (HP) in a homogeneous adult patient population with refractory hemispheric epilepsy.
Methods:   Fourteen adult patients submitted to HP were studied. Patients had to be at least 18 years old, and have refractory epilepsy, clearly focal lateralized seizures and unilateral porencephalus consistent with early middle cerebral artery infarct on magnetic resonance imaging (MRI). All patients were submitted to functional hemispherectomy. We analyzed age of seizure onset, age by the time of surgery, gender, seizure type and frequency, interictal and ictal electroencephalography (EEG) findings, MRI and IQ scores preoperatively; seizure frequency, drug regimen, and IQ outcome were studied postoperatively.
Results:   Mean follow-up was 64 months. All patients had frequent daily seizures preoperatively. All patients had unilateral simple partial motor seizures (SPS); 11 patients had secondarily generalized tonic–clonic (GTC) seizures and five patients had complex partial seizures (CPS), preoperatively. All patients had hemiplegia and hemianopsia. Twelve patients had unilateral EEG findings, and in two epileptic discharges were seen exclusively over the apparently normal hemisphere. Twelve patients were seizure-free after surgery and two patients had at least 90% improvement in seizure frequency. Pre- and postoperative mean general IQ was 84 and 88, respectively. Five of the twelve Engel I patients were receiving no drugs at last follow-up. There was no mortality or major morbidity.
Conclusions:   Our results suggest that well-selected adult patients might also get good results after HP. Although good results were obtained in our adult series, the same procedure yielded a much more striking result if performed earlier in life.     

The Role of Timing in Testing Nonverbal IQ in Children with ASD

15 School-aged high functioning children on the autistic spectrum were compared with a neurotypical cohort on the WISC-III and the KABC-II, to determine the impact of the relatively more strict timing criteria of the former test on the evaluation of nonverbal intelligence. Significant group effects, showing lower performance by the ASD group were found for three of the five sub-tests for the WISC but not for the KABC, peaks and troughs were more evident for the WISC, and the evaluation of intellectual level was also markedly lower for ASD children on the WISC-III as opposed to the KABC-II. The results are discussed in terms of how speed of processing can impact on how children with ASD are ‘matched’ against neurotypical samples.     

Neurocognitive deficits in medulloblastoma survivors and white matter loss

Although previous studies have documented a significant risk of intellectual loss after treatment for childhood medulloblastoma (MED), the pathophysiology underlying this process is poorly understood. The purpose of this study was to test the hypotheses that (1) patients treated for MED in childhood have reduced volumes of normal white matter (NWM) related to their treatment with craniospinal irradiation with or without chemotherapy, and (2) deficits in NWM among patients surviving MED can at least partially explain deficits in their intellectual performance. Eighteen pediatric patients previously treated for MED were matched on the basis of age at the time of evaluation to 18 patients previously treated for low-grade posterior fossa tumors with surgery alone (mean difference, 3.7 months). Evaluations were conducted with age-appropriate neurocognitive testing and quantitative magnetic resonance imaging by using a novel automated segmentation and classification algorithm constructed from a hybrid neural network. Patients treated for MED had significantly less NWM (p < 0.01) and significantly lower Full-Scale IQ values than those treated for low-grade tumors (mean, 82.1 vs 92.9). In addition, NWM had a positive and statistically significant association with Full-Scale IQ among the patients treated for MED. We conclude that irradiation- or chemotherapy-induced destruction of NWM can at least partially explain intellectual and academic achievement deficits among MED survivors.     

A prospective study of children with head injuries: IV specific cognitive deficits

Abstract

Twenty-five children with a head injury resulting in a posttraumatic amnesia of at least one week were compared with an individually matched group of 25 children with orthopedic injuries. Both groups were studied a few weeks after the accident and then again at 4 months, 1 year and 2% years after the injury. The head injury group showed a pcrsistent deficit on the WISC Performance IQ scale; the deficit on the Verbal IQ scalc was more transient. An extensive battery of neuropsychological tests was employed to identify specific deficits not shown on the WISC. On the whole, these tests shvwed a pattern of results similar to that found with the WISC, and in most cases children without deficits on the Performance IQscale ofthe WISC also did not show deficits on the battery of specific tests. However, in a few cases, tests of speed of visuo-motor o r visuo-spatial functioning picked u p deficits attributable to the head injury which occurred in children with normal scores on the WISC.     

Detecting epilepsy‐related cognitive problems in clinically referred children with epilepsy: Is the WISC‐IV a useful tool?

Purpose: The Wechsler Intelligence Scale for Children – Fourth Edition is the most widely used intelligence quotient (IQ) test in use today. However, despite numerous studies on IQ in childhood epilepsy, data exist almost exclusively from prior editions of the test, and no studies to date provide information on the sensitivity of specific WISC‐IV scores (full‐scale IQ [FSIQ], index, and subtest scores) to epilepsy‐related cognitive impairments. The goal of this study was to determine the relative sensitivity of WISC‐IV index and subscale scores in detecting cognitive problems in a group of clinically referred children with epilepsy compared to matched controls, and to define the relationship among WISC‐IV scales, demographic factors, and epilepsy‐related variables. Methods: WISC‐IV data for children with epilepsy and high seizure burden were obtained from the Alberta Children’s Hospital (ACH) and the New York University Comprehensive Epilepsy Center (NYU), two tertiary care medical centers for pediatric epilepsy. All children were clinically referred and received a standard assessment including WISC‐IV. Matched controls were obtained from the WISC‐IV Canadian and American standardization samples. Key Findings: WISC‐IV scores from 212 children were included: 106 children with epilepsy (46 girls, 60 boys; mean age 11.0 years, standard deviation [SD] 3.1; parental education 14.5 years, SD 2.8), and 106 controls matched for age, gender, ethnicity, and parental education. Of the children with epilepsy, 44 had a clearly lateralized focus on electroencephalography (EEG) involving either the right or left hemisphere (26 left, 18 right). FSIQ for the epilepsy group was significantly lower than for controls, and 36.8% of children had IQs compatible with intellectual disability (FSIQ < 70), versus <1% of controls. In children with epilepsy, Working Memory and Processing Speed Index scores were lower than those for Verbal Comprehension and Perceptual Reasoning (p < 0.01). At the subtest level, scores for children with epilepsy were highest on visual and verbal subtests measuring reasoning skills such as Matrix Reasoning, and lowest on Coding (mean 5.93, SD 3.6). In terms of percentage of children on each subtest with low scores (i.e., scores below 2 SDs from the expected normative mean of 10), the Coding subtest identified the most children (28.3%) with low scores, and the Similarities subtest identified the fewest (16%). Later age at onset and shorter epilepsy duration were both correlated with higher WISC‐IV FSIQ and index scores (r correlation coefficient values ranging from 0.36 to 0.44, p < 0.0001), and number of current and previous antiepileptic drug trials were both inversely correlated with FSIQ and index scores (r ?0.27 to ?0.47, all p‐values < 0.01). Neither the FSIQ nor the index scores were significantly related to seizure frequency. A similar pattern was found for subtest scores. No differences in FSIQ, index scores, or subtest scores were found between children with left‐ and right‐hemisphere seizure foci, or between those with positive or negative magnetic resonance imaging (MRI) findings. Significance: The WISC‐IV is sensitive to epilepsy‐related cognitive problems in clinically referred children with high seizure burden, particularly problems relating to expressive verbal, working memory, and processing speed difficulties. Compared to healthy children, these children have a very high rate of cognitive difficulties as assessed by the WISC‐IV. The usefulness of the WISC‐IV in detecting cognitive deficits in children with milder forms of epilepsy remains to be determined.     

Wisc/Wisc-r comparisons in a learning-disabled population: Equivalence of summary IQ measures

Abstract

Learning-disabled children referred for neuropsychological evaluation were administered either the WISC or WISC-R in order to determine the comparability of the two tests. The results indicated no significant differences between WISC and WISC-R with respect to Verbal IQ, Performance IQ, and Full Scale IQ. Examination of groups of children exhibiting various patterns of Reading, Spelling, and Arithmetic performances on the Wide Range Achievement Test also yielded nonsignificant differences between WISC and WISC-R Verbal, Performance, and Full Scale IQs. These results suggest that the summary IQ scores of these two tests are equivalent for this population.     

Psychological and electroencephalographic study in school children with iron deficiency.

Two groups were chosen from a randomly selected group of one hundred 6-12 years old primary school children. One group was formed by iron deficient (ID), not anemic children, and a control group (C) by iron replete children. Both groups, matched by age, sex, and sociocultural level, were studied using WISC-R, a computerized test of learning (DEL) and a qEEG. The WISC-R test showed that ID children had significantly lower values in WISC items of information, comprehension and verbal, performance and full scale IQ than C children. On the other hand, the EEG power spectrum showed more theta energy in all leads using Laplacian montage and more delta energy in frontal areas using referential montage in ID than in C children. It was found that beside the well known effect of iron deficiency upon intellectual performance during childhood, the EEG power spectrum of ID children had a slower activity than in iron replete children suggesting a developmental lag and/or a CNS dysfunction.     

Exploring the evaluation of antiepileptic drug change in people with intellectual disabilities and high-frequency epileptic seizures: seizure control and sustained responsiveness to the environment

PURPOSE: Optimum antiepilepsy medication should be successful in reducing seizures with minimal adverse effects on the patient's ability to concentrate or general level of awareness. The purpose was to investigate the potential of a method of measuring responsiveness to environmental events as a means of reflecting awareness levels among people with intellectual disabilities undergoing review of medication for high-frequency epileptic seizures. METHODS: Observations of 22 participants referred to a specialist clinic were conducted three times a month over a 5-month period following the initial baseline measures and clinical intervention. Behavioral responsiveness was measured by calculating the likelihood of appropriate activity occurring given the occurrence of staff interaction. This likelihood was represented by the statistic Yule's Q. Seizure frequency was also evaluated. RESULTS: Participant responsiveness after drug review was similar to baseline indicating an absence of long-term adverse effects. Participants experienced a significant decrease in seizure frequency. CONCLUSION: It was concluded that drug review led to seizure reduction while behavioral measurement confirmed no loss of responsiveness.     

Treatment and long-term prognosis of myoclonic-astatic epilepsy of early childhood

PURPOSE: We retrospectively studied patients with myoclonic-astatic epilepsy of early childhood (MAE) to investigate the most effective treatment and long-term seizure and intellectual prognosis. SUBJECTS: Eighty-one patients with MAE were recruited from among 3600 patients with childhood epilepsy according to the ILAE criteria of MAE. METHODS: We retrospectively investigated the clinical characteristics and ultimate prognosis of the patients with MAE from the medical records. The effects of various antiepileptic drugs, ketogenic diet and ACTH treatments on myoclonic-astatic seizures (MS/AS), apparently a hallmark of this unique epileptic syndrome, were also studied. RESULTS: MS/AS in 89 % of the patients disappeared within 1 to 3 years despite initial resistance, but generalized tonic-clonic or clonic seizures [G(T)CS] tended to continue. The most effective treatment for the MS/AS was ketogenic diet, followed by ACTH and ESM. At the last follow-up, 55 patients or 68 % of all the patients had remission of epilepsy, 11 patients or 14 % experienced a recurrence of GTCS after a long remission period but easily regained control, and the remaining 15 patients or 18 % continued to have seizures and intellectual outcomes were poor. In one half of these patients with poor outcomes, repeated minor epileptic status and nocturnal generalized tonic seizures persisted. A family history of epilepsy and a combination of minor epileptic status are risk factors for poor outcomes. CONCLUSION: MAE is considered to form a clinical spectrum ranging in its main seizure type from myoclonic to atonic, and in seizure and intellectual outcomes from benign to malignant. The overall prognosis, despite initial resistance to treatment, appears to be much better than originally thought when ILAE definitions excluding SME are followed.     

Neurophysiological and neuropsychological differences related to performance and verbal abilities in subjects with mild intellectual disability

The present study compared two group of subjects with intellectual disability. The 44 subjects in group 1 had equivalent verbal and performance IQs (67 and 64, respectively), while the 12 subjects in group 2 had an intellectual performance IQ which was ≥10 points above their verbal performance IQ (80 and 65, respectively). The second group showed an alpha peak at a higher frequency and an evoked potential closer to normality. The decrease in the voltage of the P300 wave in group 1 was especially significant. The cognitive evoked potentials were also different between the two groups.     

Reading disorders in children with partial epilepsy

This study represents a neuropsychological evaluation of reading ability in children with partial epilepsy (PE), aged 7-14 years, of normal intelligence, without neurological deficits and physical handicaps, appropriate environment stimulation and learning opportunities. A control group consisted of 202 healthy school children. Reading disabilities were significantly more frequent in children with partial epilepsy, especially in patients with PE with complex symptomatology. The children from the control group had better results of the tests of both verbal and performance intelligence, but children with reading disabilities had greater performance IQ than verbal IQ. Significant intergroup difference was related to the children aged 7-10 years. Positive evidence of left dominant hemisphere superiority for reading has been shown. Dyslexia was significantly more frequent in patients with left hemisphere epileptic foci, than in those with right hemisphere focal EEG changes.     

小儿难治性癫痫综合征的外科治疗

目的总结外科手术治疗27例小儿难治性癫痫综合征病人的经验。方法术前评估和术中脑电检查显示为局灶性改变者行致痫灶切除、脑叶切除或多软膜下横纤维切断(MST)。检查提示一侧半球为主多灶性改变者,术中行多脑叶切除联合MST或(和)胼胝体部分切开。结果本组随访1-8年,平均4.5年。27例病人中有14例获得Ⅰ级(Engel分级),8例获得Ⅱ级,3例为Ⅲ级。平均智商(IQ)从术前的61.4分提高到75.0分,癫痫病程和术前药物难治的时间越短,智商改善越明显。本组4例病人出现暂时性的并发症,无手术死亡。结论对小儿难治性癫痫综合征进行早期外科干预,可以有效地控制癫痫发作、改善智力损害和避免生活残疾。