Neuropsychological outcome of childhood Epilepsy: A

study of cognitive functioning and academic skill

development.

Running Title: Neuropsychological outcome of Epilepsy

Dr. Smita A. Desai, Ph.D; Eeshani Chakraverty, M Phil

Affiliation:

Name: - DRISHTI, A Learning Center

Address: 205-206 Midas Chambers, Off New Link Rd, Andheri

(W), Mumbai – 400 053, INDIA.

Fax: 022-26732494; Tel: 022-26732496/97

e-mail: smita@drishtionline.com

Corresponding Author: Dr. Smita Desai.

Key words: Cognitive functioning, academic skills, epilepsy, learning

difficulties.

Neuropsychological outcomes of childhood epilepsy: A study of cognitive functioning

and academic skill development

Abstract:

The total number of people suffering from Epilepsy in our country is quite large. There is accumulating evidence

that epilepsy must be considered as a major risk factor for childhood development and learning difficulties. This

study was aimed at comparing the cognitive functions and academic achievement of children having Epilepsy with

those not having Epilepsy, with both groups being referred for academic difficulties. The study sample consisted of

two groups of children, one with no history of Epilepsy (N=39) and the other with a history of Epilepsy (N=31) in

the age range of 8 to 12.11 years. The cognitive and academic functions were assessed using standardized

assessment tools. The study showed that there were significant differences between the two groups in specific areas

of cognition; however no significant difference was found in information processing skills and academic

achievement measures.

Introduction

Epilepsy occurs when there are recurrent seizures due to abnormal electrical activity in the brain. Not all fits or

seizures are convulsive. A single seizure does not mean epilepsy, although the symptoms are the same. Epilepsy is

the name given to seizures that can occur more than once because of an underlying abnormality in the brain

(Aldenkamp, 1987). The prevalence rate of epilepsy in India stands at around 5/1000 (Ray, et al., 2002). At this

rate, present estimates of people suffering from epilepsy in this country would be more than 5 million!!

There is accumulating evidence that epilepsy must be considered a major risk factor for childhood development.

(Aldenkamp & Dodson, 1990; Vinayan et al., 2005). Children with epilepsy as a group are at undue risk of

developing learning difficulties (Rutter et al., 1970; Thompson, 1987). Learning problems occur in an estimated 5-

50% of children with epilepsy. (Thompson, 1987). Community based studies in the UK (Verity & Ross, 1985)

show that 30% of the investigated children with epilepsy underachieve in school and that many are referred to

special education.

Classroom performance is dependent upon several factors: the child’s personality structure, environmental factors

and cognitive functions. The interrelationships between cognitive functioning and epileptic conditions are of

exceptional complicity (Aldenkamp & Dodson, 1990; Noeker et al., 2005). Learning, an adaptive process by which

behaviour is modified through experience, can be adversely affected by epilepsy, which is characterized by episodic

disruption of neural activity. Seizures have an immediate effect on cognitive function. This effect is more distinct if

the seizures occur in series, than if they occur as single events.

Certain aspects of seizures correlate with intellectual functioning. Early onset of generalized convulsions is

associated with lower IQ scores than early onset of partial seizures. (O’Leary et al, 1983). Primary generalized and

secondarily generalized seizures seem to affect neuropsychological results more than partial seizures do (Giordani,

et al, 1985). Intellectual impairment is also related to age of onset, a long history and high frequency of seizures.

Earlier the age of onset, the extent of intellectual impairment is considered to be greater and with a long-term

impact. Diurnal seizures are seen to have direct effects on the processes of alertness, short-term learning, and

abstract reasoning; nocturnal seizures are seen to have detrimental effects on language functions, memory, and

alertness (Renier, 1987).

There may be learning disabilities brought about through disruption of longer-term processes of storage and

retrieval and by prolonged and permanent reduction in the brain’s capacity to react adaptively to incoming

information. The effects of epilepsy on learning have been investigated by examination of processes integral to

learning, such as attention and memory, and by consideration of the end results, mainly educational attainments.

(Bailet & Turk, 2000; Binnie, Channon, & Marston, 1990; Motte, 2001).

Most studies are focused on reading achievement. In a study by Rutter et al (1970), children with epilepsy showed a

reading retardation by approximately 12 months. Other studies suggest that arithmetic is the academic skill most

impaired (Ross & West, 1978).

In a comparative study of two groups (one epileptic and the other non-epileptic) of learning disabled, findings

revealed specific patterns of cognitive dysfunction in the LD group with epilepsy (Dekker, et al, 1989). These

results are similar to another study where the epileptic group was seen to have specific deficits in short term

memory, memory span, attention deficits, concept formation, logical thinking, slowing of information processing in

complex task configurations and found to be related to underachievement in arithmetic. (Aldenkamp, 1987).

Most data based on neuropsychological assessment of children with epilepsy show that academic problems arise

from specific cognitive deficiencies rather than generalized cognitive dysfunction. Rutter et al (1970) reported

impaired memory functioning and reduced attention capacity.

Factor analytical studies performed on several groups of patients with intractable seizures indicate that the most

consistent predictor of neuropsychological impairment and show the relative prominence of the factor of

distractibility, in which the subtests of coding, digit span and arithmetic are over represented. The study thus

concludes that attention factors may be particularly vulnerable to seizure activity (Kupke & Lewis, 1985).

Epilepsy and a concurrence of learning and behaviour difficulties are seen to have long-term, wide

ranging outcomes (Oostrom et al., 2003; Sillanpaa, 2004).

Methodology

The present study was carried out at Drishti, a tertiary referral center for assessments & therapy in Mumbai.

Aims:

To explore if there are any differences in the cognitive functioning & academic skills of two samples of students

referred for assessment of learning difficulties. One sample of students has a history of epileptic seizures, whereas

the other has no history of epilepsy.

Research sample:

Demographic data and data from standardized evaluations were studied for this total sample of 70 students. Of

these, one group of 31 students had a history of epileptic seizures and was currently on Anti-Epileptic Drug’s

(AED’S), or had current occurrence of seizures (Group with Epilepsy-GEp). The other group of 39 students had no

occurrence of epileptic seizures (Group with No Epilepsy-GNEp).

In the total sample, there were 45 males and 25 females. In the sample group with epilepsy (GEp), there were 19

males and 12 females, while in the group with no history of Epilepsy (GNEp) there were 26 males and 13 females.

The age range extended from 8-12.11 years. All the children were from an urban population. These children were

referred to the center for assessment by parents or referring agencies i.e. the treating neurologist/ psychiatrist/

pediatrician or the school.

Procedure:

This study is a retrospective analysis of psycho-educational assessment data. Assessments were individualized to

suit the presenting complaint. Assessment tools used were formal and standardized. Selective data from these

assessments was analyzed for the study. Assessment areas analyzed for this study were cognitive functioning,

information processing, attention and academic skills of reading, written language, and math.

Materials:

The assessment data analysed was across the areas of cognitive functioning, information processing, attention, and

academic achievement. Demographic and developmental data was collected using a case history form filled out by

parents.

The selective data analysed include the composite scores from the following instruments:

Weschler Intelligence Scale for Children-Indian adaptation (WISC)(Bhatt, M; 1973) :

This test measures the verbal as well as non-verbal intelligence of the student using the verbal and performance

scales. The sub-test scaled scores range from 0-20 with an average of 10. Composite scores include the Verbal IQ,

Performance IQ and the Global IQ.

Ross Information Processing Assessment (RIPA) (Swain, D; 1999):

The RIPA-P quantifies & describes cognitive-linguistic deficits in individuals between the ages of 5-0 and 12-11

yrs. It can be used to identify specific individual strengths and weaknesses, to develop and guide rehabilitation

goals and objectives. Information Processing Quotient (IPQ): The IPQ comprises the standard scores of all eight

RIPA-P sub-tests, and gives a comprehensive estimate of a child's overall information processing abilities.

Woodcock-Johnson Psycho-educational Battery-Revised (WJ-R )(Woodcock, R & Johnson, M; 1989-1990):

The WJ-R is a wide range comprehensive set of individually administered tests for measuring cognitive abilities,

scholastic aptitude and achievement. This test yields age equivalent and grade equivalent scores for all the sub-

tests. The sub-tests can be grouped into reading, written language, and Math clusters. None of the sub-tests are

timed tests. Derived Standard scores (SS) and Percentile ranks (PR) are peer comparison statements.

Analysis:

The data was analysed using appropriate statistical tools. Percentages were calculated for the various sample

characteristics (viz. age, sex, speech milestones, and motor milestones) for both the groups. The student’s

t-test for independent samples was used to estimate significant differences between the groups in the areas

of cognition (using the VIQ, PIQ, GIQ, IPQ scores) and academic achievement (Reading comprehension,

Written expression, Math calculations). The statistical analyses were carried out using Microsoft Excel

2000.

Results & Discussion

The purpose of this study was to examine whether there are any significant differences in the cognitive functioning,

information processing and academic skills development between two groups of children, with one group suffering

from epilepsy (GEp) and the other group with no epilepsy (GNEp).

Table 1 provides an overview of the distribution of the demographic variables of age and gender. The age of the 70

children who formed the study sample ranged from 8 years to 12.11 years. In the GNEp, 41.03% children were in

the age range of 8 to 8.9 years, 58.97% children were in the age range of 10 to 11.11 years and zero percent (0%)

children were in the age range of 12 to 12.11 years. In the GEp 54.84% children were in the age range of 8 to 8.9

years, 65.48% children were in the age range of 10 to 11.11 years and 9.68% children were in the age range of 12 to

12.11 years. There were 66.67% male children and 33.33% female children in the GNEp. The GEp had 61.29%

male children and 38.71% female children (Table 1 here).

The demographic data collected during the study shows that there were a greater number of males (64.28%)

referred for assessment of learning difficulties. This was true across both the groups. A greater number of students

in the non-epilepsy group (58.97%) were in the age range of 10-11.11 years, whereas the larger group in the

epilepsy group was in the age range of 8-9.11 years. Thus, it can be seen that children with Epilepsy were referred

at a relatively younger age for assessment of learning difficulties.

Table 2 shows the developmental characteristics of speech development and motor development of the two groups

in the study. A study of these developmental milestones of both the groups shows that 45.16% of the GEp had

delayed speech development as compared to 30.77 % of those in the GNEp. Similarly, 19.35% of the GEp showed

a delay in motor development as compared to 12.82% of the GNEp. (Table 2 here)

Cognitive functioning of the sample was studied through the use of two measures: intellectual functioning and

information processing. Table 3 shows the difference in cognitive functioning between GNEp and GEp. The

t-test was used to compute the differences. The mean VIQ for the GEp was 87.71 placing it in the borderline

range, whereas that of the GNEp was 96.97 placing it in the average range. The mean PIQ for the GEp was 93.74,

being in the average range, whereas that for the GNEp group was 106.18 also being in the average range. The mean

full scale IQ of the GEp was 89.58 placing it at the borderline of average range, whereas it was 101.54 for the

GNEp placing it in the average range.

All the three intelligence quotients were lower for the GEp. The mean IQ scores of the GNEp were higher than the

GEp across all the areas of cognition (viz., VIQ, PIQ, GIQ and IPQ) measured in the current study. The ‘t’ values

indicated statistically significant differences ( p< 0.05) in the Verbal Intelligence Quotient (VIQ), Performance

Intelligence Quotient (PIQ) and Global Intelligence Quotient (GIQ) between the two groups. Scores on the RIPA

were taken in its composite form as the Information Processing Quotient (IPQ). With the mean IPQ of the GEp

being 81.64 and the GNEp being 83.79, the difference was not found to be statistically significant. (Table 3 here)

Table 4 shows the difference between GNEp and GEp in the areas of academic achievement on the WJ-R. The

mean scores were higher for the GNEp across all the areas of academic achievement (viz., Reading, Writing and

Mathematics). However, a study of the mean scores of the two groups showed that the reading comprehension

scores of both the groups fell below the mean. However, the reading scores of the GNEp was 81, SD 13.71, falling

in the range of ‘low average’ classification, whereas the scores of the GEp being 74.42, SD=20.43, fell in the ‘well

below average’ classification.

Mean standard score in the area of written expression for the GNEp was 85, SD=18.34, placing performance in the

low average range, whereas that for the GEp was 76.29, SD= 23.89, thus placing it in the range of well below

average functioning. Mean SS in the area of Math calculations for the GNEp was 96.38, SD= 19.98, placing it in

the range of average functioning and that for the GEp was 91.71, SD= 23.28 placing it also in the range of average

functioning. The t-test was used to compute the differences. No significant difference was found between the two

groups across the different areas of academic achievement (viz., Reading, Writing and Mathematics) measured in

this study. (Table 4 here)

The relationship between cognitive functioning and epilepsy is seen to be complex. Studies have shown

(Bourgeois, 1998; Noeker, et al., 2005) that children with epilepsy are seen to have poorer cognitive functioning

and attention skills than their peers. However, different studies indicate these cognitive dysfunctions to be specific

rather than global (Germano, et al., 2005). These deficits were seen to be in verbal processing, language tasks,

visual perception and memory. This also supports the findings of this study where the mean VIQ of the GEp is seen

to be on the borderline of average range and significantly lower than that of the GNEp.

Related literature also indicates the presence of non-verbal intellectual difficulties, with children with epilepsy

being over represented in the lowest tenth percentile (Giordani, 1985; Hoie, B et al., 2005). However, results from

this sample indicate adequate functioning in the area of non-verbal intelligence (PIQ), although there are significant

differences between the two groups.

Germano et al. (2005) and Carlsson et al. (2000) report that none of their subjects affected by epilepsy showed any

global intellectual deficit (as measured by full scale IQ on the WISC_R). This is also seen in the analysis of the

current study. Reports of impaired memory, abstract reasoning, and visual-spatial orientation are also present

(Rugland, 1990; Stores, 1981). However; some studies find these cognitive deficits to be transient (Saint-Martin et

al., 2001). As found with the sample of the present study, Schouten et al (2002) also report that their sample of

children with and without epilepsy performed similarly on tasks of recall and retention.

Although children with epilepsy tend to exhibit more reading difficulties than their classmates, very few studies

have systematically investigated the relationship between these two factors. A study by Vanasse, et al, (2005)

indicates that although the reading achievement of their epilepsy group was close to 2 years lower than

expectations, these children did not differ from the non-epilepsy group on the phonological processing tasks.

Results of the current study also indicated that although reading difficulties were present in the epilepsy group, they

did not differ significantly in achievement from the non-epilepsy group, which was also referred for academic

difficulties.

Results of studies by Papavasiliou et al. (2005) and Yung, et al. (2000) indicate that greater difficulties were seen in

the epilepsy group on written language skills when compared with the control group. Results of the present study

show deficits in the area of written language achievement of the group with Epilepsy, but no significant difference

between the two groups. Studies have also reported arithmetic as being the academic skills most impaired

(Aldenkamp, 1983, 1987; Ross & West, 1978). However, in the present study, performance of the GEp on the math

calculation subtest was adequate and comparable to the GNEp.

Carlsson et al (2000) also investigated as to whether there was an association between dyslexia and epilepsy. Two

groups, both identified with dyslexia, but one with epilepsy and the other without, were compared. Results

indicated no significant differences on neuropsychological variables or spelling ability. However, those with

epilepsy did show more reading errors.

The results of this study and sparse literature in this area reflect upon the need to explore further into the possible

similarities in neuropsychological processes for those suffering from epilepsy and those with dyslexia without the

presence of epilepsy. Studies need to be conducted on larger samples (small ample size was one of the limitations

of the current study). Also, these studies need to then differentiate between different types of epilepsy, which this

study did not do.

In order to help out the children with epilepsy, recommendations are mainly in the areas of drug therapy,

parent counseling, school-teacher education and improving the Quality of life of the individual

( Bourgeois, 1999; Galletti, 2004; Malhi & Singhi, 2005).

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Table 1: Sample characteristics-demographic variables of age & gender.

Variables Non Epilepsy Epilepsy Total

SEXMale 67% 61.29% 64%

Female 33% 38.71% 35.71%

AGE

8-9.11 41.03% 54.84% 47.14%

10-11.11 58.97% 35.48% 48.57%

12-12.11 0% 9.68% 4.29%

Table 2: Sample characteristics: developmental delays.

Variables Non Epilepsy Epilepsy

Speech

(Developmental delay)

Absent 69.23% 54.84%

Present 30.77% 45.16%

Motor

(Developmental delay)

Absent 87.18% 80.65%

Present 12.82% 19.35%

Table 3: Differences between GNEp and GEp in cognitive functioning.

*p<0.05

VIQ = Verbal Intelligence Quotient

PIQ = Performance Intelligence Quotient

GIQ = Global Intelligence Quotient

IPQ = Information Processing Quotient

Variables

Non Epilepsy

(N=39)

(Mean ± SD)

Epilepsy

(N=31)

(Mean ± SD)

t

(df = 68)

VIQ 96.97 ± 15.58 87.71 ± 17.77 2.32*

PIQ 106.18 ± 17.65 93.74 ± 16.75 2.99*

GIQ 101.54 ± 16.34 89.58 ± 16.94 2.99*

IPQ 83.79 ± 27.55 81.64 ± 20.09 0.36

Table 4: Difference between GNEp and GEp in academic achievement.

*p<0.05

NS: Not Significant

Variables

Non Epilepsy

(N=39)

(Mean ± SD)

Epilepsy

(N=31)

(Mean ± SD)

t

(df = 68)

Reading

(Comprehension)81.00 ± 13.71 74.42 ± 20.43 1.61 NS

Writing

(Expression)85.00 ± 18.34 76.29 ± 23.89 1.73 NS

Mathematics

(Calculation)96.38 ± 19.98 91.71 ± 23.28 0.90 NS