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Epilepsy & Behavior 5 (2004) 937–944

Learning disability: occurrence and long-term consequencesin childhood-onset epilepsy

Matti Sillanpaa*

Departments of Child Neurology and Public Health, University of Turku, Turku, Finland

Received 2 April 2004; revised 16 August 2004; accepted 17 August 2004

Abstract

This study analyzed the occurrence of learning disability (LD) in adults with childhood-onset epilepsy and the impact of LD onmedical and social outcome. Any LD occurred in 76%: in 57% of mentally normal (IQ > 85), in 67% of mentally near-normal(IQ = 71–85), and, self-evidently, in all mentally retarded (IQ < 71) adults. Half of the patients (51%) with LD had mental retarda-tion. In multivariate analysis, mental retardation and subsequent LD were predicted by occurrence of cerebral palsy (odds ratio[OR] = 3.83; 95% confidence interval [CI] = 1.77–8.28, P = 0.0006), onset of epilepsy before the age of 6 years (OR = 3.63, 95%CI = 1.57–8.42, P = 0.0026), and poor early effect of drug therapy (OR = 2.78, 95% CI = 1.43–5.39, P = 0.0025). Among mentallynormal or near-normal subjects, a symptomatic etiology of epilepsy was the only predictor (OR = 7.72, 95% CI = 3.02–19.76). Thedegree of LD significantly affected medical, social, and educational long-term outcomes.� 2004 Elsevier Inc. All rights reserved.

Keywords: Learning disability; Mental retardation; Near-normal intelligence, Epilepsy; Status epilepticus; Prognosis; Relapse; Social competence;Reproductive activity; Driving license

1. Introduction

People with epilepsy have for centuries been believedto be notorious underachievers at school or incapable ofattending school due to a cognitive deficit. The belief hasinvariably been based on studies about epilepsy in spe-cial schoolchildren and institutionalized patients and,thus, biased by selection [1]. Indeed, a WHO reportfound the main problem to be the lack of truly unbiasedsamples for testing [2]. Early data from institutionsshowed 35–60% of the mentally retarded to have epi-lepsy [3,4]. More recent, population-based studies [5–7]found epilepsy in 23–33% of mentally retarded people.On the other hand, among those with epilepsy, 31–41% are reportedly retarded [8–12].

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doi:10.1016/j.yebeh.2004.08.008

* Fax: +358 2 333 8439.E-mail address: matti.sillanpaa@utu.fi.

There are still only few epidemiological research-based data on cognitive deficits causing learning distur-bances in people who have epilepsy. One fundamentalproblem is the inconsistent use of the terms mentalretardation (MR) and learning disability (LD). Noconsensus so far exists, because, in a very recent discus-sion, some would like to keep the terms separated [13],some others want to have the term LD as an umbrellaterm for all conditions with learning disability [14], andthe remaining authors simply do not discuss the prob-lem. Most of the prevalence studies are cross-sectionaland give only rates of prevalence of MR [8,10–12,15–19], omitting those who have LD but normal intelli-gence (IQ > 70) [20]. In the National Child Develop-ment Study of 15,496 children, 64 children haddeveloped epilepsy by the age of 11. At that age, 43were in normal schools, 20 were in special schools,and 1 child was at home [10]. In a Scandinavian studyof 36,500 children, 155 had epilepsy. Of them, 20% had

938 M. Sillanpaa / Epilepsy & Behavior 5 (2004) 937–944

both MR and cerebral palsy and an additional 21%had MR only [11]. In another Scandinavian popula-tion-based study, MR occurred in 39% of 198 childrenwith epilepsy who were derived from an unselectedpopulation of 38,500 children [17]. Still another Scandi-navian population study of 49,000 children [12] re-ported MR in 38% (mild in 14% and severe in 24%).Cerebral palsy was much more common among chil-dren with severe MR (49%) than among those withmild MR (14%). From the same patient series, Beck-ung et al. [21] later recruited those who had no otherneurological deficits, such as MR, cerebral palsy, andsimilar deficits, for the assessment of their sensoryand motor function. Thirty percent of their study sub-jects with epilepsy but without additional neurologicalimpairments exhibited gross motor functional deficitsin balance, coordination, and speed. The study didnot consider the intelligence level among these nonre-tarded subjects.

Brorson and Wranne [22] followed 194 of 195 chil-dren for 12 years with respect to survival and seizureprognosis. An initial ‘‘neurodeficit’’ or abnormal neuro-logical examination, MR, or frequent seizures or anycombination proved to be a negative prognostic factor.Forty-one percent of patients with a neurological deficitand 79% of those without any neurodeficit were in 3-year terminal remission at the end of follow-up.

Camfield et al. [23] classified their patients with re-spect to intelligence level into four groups: normal, mildto severe mental retardation, learning disorder, andlearning disorder with behavioral disorder. The lattertwo groups were not defined. Twelve percent were clin-ically assessed as mentally retarded and 16% had alearning disorder. No data were given on the remaining4%. A Japanese clinic-based follow-up study [18] founda significantly higher remission rate in the mentally nor-mal than in the mentally retarded (IQ < 70) (76% vs37%). Again, no distinct difference was observed be-tween MR and LD, but 72% attended regular classesin an ordinary school. Of 49 mentally retarded, 14% at-tended regular classes at ordinary schools; 27% attendedspecial classes at ordinary schools, and the remaining41% were at schools for handicapped, in institutions,or invalids at home.

Our purpose was to study the occurrence of LDs andtheir effects on medical and social outcomes and factorsthat might affect outcome. We hypothesized that, evenin the long run, the outcome is not as favorable in thelearning disabled as in patients with no LD.

2. Subjects and methods

The study group was derived from a population-based cohort. It included all children aged less than16 years, who were resident in a geographically defined

catchment area of the University Central Hospital ofTurku at the end of 1964, had epilepsy [24–26], andhad at least one epileptic seizure in 1961–1964 (‘‘activeepilepsy’’). In 1972, the cases were identified on the ba-sis of patient records of hospitals, institutions, daycarecenters, special schools, and private surgeons, as wellas of the National Health Service records, which coverall citizens resident in Finland. The case identification,made by one investigator only (M.S.), was very exten-sive, and continuing surveillance of the national registryrevealed only three patients who met the inclusion crite-ria but had not been included in the study. Based onthis recruitment procedure, altogether 245 patientscould be ascertained as patients who met the inclusioncriteria.

The cohort was followed for 45 years. Three patientsdied before the age of 3 and were considered too youngfor the assessment of LD. Thus, 242 patients (132 males,110 females) were available for the study. Data were col-lected retrospectively for the first 10 years and then pro-spectively in examinations performed every fifth year forthe last 35 years of follow-up. In 1992, after a total fol-low-up of 35 years, patients completed a detailed ques-tionnaire and thorough face-to-face interview, physicalexamination, assessment of physical fitness, and deter-mination of cardiovascular, liver, and bone marrowfunction and fat metabolism using clinical examinationand laboratory investigation. All the children were lessthan 16 years of age at the beginning of follow-up(mean, 4.7 years; range, 3–15). Follow-up extended tothe year 2002 or to death. Fifty-seven patients died be-fore 2002. The mean age at the end of follow-up was36 (range, 5–55) years. The study design, and some med-ical and social data, including social and educationaloutcomes by evolution of seizure status and medication,have been reported previously [19,27].

The Finnish Public Health Care Administration sys-tem covers a child�s life from the fetal period to theage of 16. Public health center districts, the smallestadministrative units, constitute a countrywide network.A health care center includes a maternity health careclinic, children�s welfare clinic, and school health careorganization. In addition, municipal special child guid-ance clinics provide clinical, psychological, and similarservices. The public organization covers virtually 100%of children, and is capable of detecting any child withhealth problems, including psychological problems, suchas a LD.

Epilepsy, types and etiology of seizures, and epilepsysyndromes have been defined by the International Lea-gue Against Epilepsy [27]. Uncomplicated epilepsy is de-fined as epilepsy without any additional neurologicalimpairments, such as cerebral palsy and MR [27]. Cere-bral palsy is defined as a chronic, nonprogressive cere-bral disorder in young children that results in impairedmotor function [28]. A subject is defined as mentally

M. Sillanpaa / Epilepsy & Behavior 5 (2004) 937–944 939

normal and, accordingly, as having a normal intelligencelevel (IQ > 85), if he or she had a normal cognitivedevelopment and accomplished acceptably in the main-stream school system (compulsory school for 7- to 16-year-olds) without any special or remedial education.A subject is considered near-normal if the IQ is 71–85and he or she has received special education. Mentallynormal and mentally near-normal are also called men-tally nonretarded. MR is defined as a lifelong disordercharacterized by an inability to care for oneself like one�speers because of a low intelligence level (IQ < 70) untilthe age of 18 [29]. A subject is defined as mildly mentallyretarded if his or her IQ is 50–70, and severely mentallyretarded patients if the IQ is <50. Socioeconomic statusis defined according to the criteria of the Central Statis-tical Office of Finland [30]. Passing a Finnish matricula-tion examination is approximately equal to passing thefirst university year in the United States [27].

Severe MR is clinically obvious but was assessed bya clinical psychologist in most cases. Test results (ver-bal, performance, total) were available in the patient re-cords. Virtually all mildly mentally retarded patientswere assessed on clinical grounds, and in most casesseveral times, by a psychologist, because a psycholo-gist�s statement was necessary for public special educa-tion services, and the mainstream schools did not haveto accept mentally retarded pupils for education with-out the psychological assessment and subsequent extraresources for classroom teaching. A subject had a spe-cific LD, if he or she, even though able to read, write,and calculate, had specific difficulties in learning theseskills, was an overall slow learner, or had any otherlearning difficulty requiring special education any timeat school. Again, for school administrative reasons, vir-tually all these children were assessed by a psychologist.We also had detailed data on their primary and voca-tional education, later working history, reproductiveactivity, licensure for driving, and socioeconomic sta-tus. However, for certainty reasons, the 35-year fol-low-up questionnaire included a question ‘‘Have youever (at school age or later) had difficulties in reading,writing, or language?’’ In addition, at the same time,participants were clinically assessed by one and thesame experienced clinician using a structured studyform for motor dysfunction, language difficulties, atten-tion deficits, LD, behavioral problems, special schooleducation, and school achievements. All the patientswho had a LD had had it since school years; none ofthem had a LD of acquired origin.

For statistical analyses, Pearson�s v2 test with Fischerexact test (two-tail) and Yates�s correction when appro-priate were used for univariate analyses, Mann–Whitneytest for continuing variable comparisons, and stepwiselogistic regression analysis for multivariate analysesand odds ratios and relative risks. Computations werecarried out using SAS statistical software. P values

<0.05 were interpreted as statistically significant. TheJoint Ethics Review Committee of the Turku UniversityMedical School and the Turku University Central Hos-pital approved the study design.

3. Results

3.1. Occurrence

One-fourth (24%) of 242 patients had no LD whatso-ever. One hundred and eighty-two (76%) had some typeof LD to some degree. The occurrence was very signifi-cantly bound to the intelligence level. LDs occurred in57% of subjects with an IQ greater than 85, in 67% ofthose with an IQ of 71–85, and, self-evidently, in 100%of the mentally retarded. Half of the patients (51%) withLDs had MR. Of all subjects, 78% attended regular clas-ses at ordinary schools, 12% attended special classes atordinary schools, 9% attended training schools for men-tally handicapped, and the remaining 1% attended othertypes of schools. Reading, writing, and speech problemsin mentally nonretarded patients occurred transiently ormostly permanently in 19, 19, and 40%, respectively.Subjects with near-normal intelligence (IQ 71–85) hadsignificantly more often than mentally normal patientsreceived special education (45% vs 3%, P < 0.0001)and failed to pass compulsory school (10% vs 0%,P = 0.035). The mentally near-normal subjects alsohad hyperkinetic features in their behavior more oftenthan the mentally normal subjects (44% vs 8%,P < 0.0001). Compared with nonretarded subjects withother types of epilepsy, reading disability occurred lessoften in those with rolandic epilepsy (P = 0.0122,RR = 0.15, 95% CI = 0.02–1.08), but more often inthose with minor motor seizures (West syndrome andLennox–Gastaut syndrome) (P = 0.0322, RR = 2.73,95% CI = 1.64–4.60). The incidence of writing difficul-ties did not significantly differ by epilepsy type. Speechdisorders were more often associated with temporal lobeepilepsy (P = 0.0289, RR = 2.07, 95% CI = 1.15–3.73)and epilepsy with minor motor seizures (P < 0.0001,RR = 4.70, 95% CI = 3.37–6.57).

One hundred patients had uncomplicated epilepsy.Nineteen (19%) with uncomplicated epilepsy reportedreading problems, 18% writing difficulties, and 15%speech problems at school age and/or later. LD oc-curred significantly less often in patients with rolandicepilepsy than in patients with other types of epilepsy(6% vs 35%, P = 0.0122), and speech problems more of-ten in patients with temporal lobe epilepsy than othertypes of epilepsy (37% vs 18%, P = 0.0289, RR = 2.7,95% CI = 1.19–6.15) compared with controls. LD wasnot significantly more common among subjects withtemporal lobe epilepsy than among controls (P =0.0742, RR = 1.95, 95% CI = 0.93–4.07).

940 M. Sillanpaa / Epilepsy & Behavior 5 (2004) 937–944

3.2. Predictors of occurrence

In univariate analysis, significant predictors of theoccurrence of MR included cerebral palsy, poor early ef-fect of drug therapy, early (<6 years) onset of epilepsy,and status epilepticus (Table 1). A stepwise logisticregression analysis of the significant single determinantsshowed that independent predictors of the occurrence ofMR and subsequent LD were cerebral palsy (OR = 3.83,95% CI = 1.77–8.28, P = 0.0006), onset of epilepsy be-fore the age of (3.63, 1.57–8.42, P = 0.0026), and poorearly effect of drug therapy (2.78, 1.43–5.39, P = 0.0025).

In univariate analysis, among the mentally nonre-tarded subjects, symptomatic etiology of epilepsy, con-comitant cerebral palsy, and poor early effect of drugtherapy were significantly associated with LD, closely,but statistically nonsignificantly, followed by status epi-lepticus, male sex, and MR in relatives (Table 2). Inmultivariate analysis between the significant predictors,

Table 1Predictors of the occurrence of mental retardation among adult patients wit

Predictor Mental retardation

N Yes No

n % n

Cerebral palsyNo 189 54 28.6 13Yes 53 38 71.7 1

Poor early drug effectNo 131 38 29.0 9Yes 75 43 57.3 3

Onset of epilepsy>6 years 66 12 18.2 566 years 176 80 45.4 9

Status epilepticusNo 167 55 32.9 11Yes 75 37 49.3 3

GenderFemale 112 37 33.0 7Male 130 55 42.3 7

Epilepsy typeAll but TLE 160 59 36.9 10TLE 88 33 40.2 4

Table 2Predictors of learning disability in 149 nonretarded patients with childhood-

Predictor N LD (%)

Etiology of epilepsyIdiopathic 68 64.7Cryptogenic 54 51.8Symptomatic 120 93.3

Cerebral palsy 53 92.4Poor early drug effect 75 88.0Status epilepticus 75 84.0Male sex 130 80.8MR in relatives 46 84.8Onset of epilepsy <6 years 137 77.8Temporal lobe epilepsy 82 78.1

a symptomatic etiology of epilepsy was the only predic-tor of the occurrence of LD in mentally nonretarded pa-tients (OR = 7.72, 95% CI = 3.02–19.76).

3.3. Seizure outcome

LD of any kind and seizure outcome are closely inter-related. Table 3 shows that 90% of mentally normal sub-jects with no LD, approximately 70% of mentallynormal subjects with LD, and 54% of the mentally re-tarded subjects achieved 5-year or longer seizure-freeperiods at any stage of follow-up (remission ever),whether on medication or not. Intelligence level didnot determine seizure outcome among either the men-tally retarded or the nonretarded subjects.

With respect to the occurrence of relapses, again, pa-tients with any degree of MR and those with any LD,regardless of MR, relapsed significantly more often thanothers (Table 4). The relapse rate was very high among

h childhood-onset epilepsy

P OR 95% CI

%

<0.00015 71.4 1.05 28.3 6.33 3.22–12.45

<0.00013 71.0 1.02 42.7 3.29 1.82–5.95

<0.00014 81.8 1.06 54.6 3.75 1.88–7.49

0.01512 67.1 1.08 50.7 1.98 1.14–3.46

0.13855 67.0 1.05 57.7 1.49 0.88–2.51

0.60931 63.1 1.09 59.8 1.15 0.67–1.99

onset epilepsy

P OR 95% CI

<0.00011.00.59 0.28–1.227.64 3.19–18.28

0.0015 4.90 1.69–14.240.0026 3.22 1.46–7.100.0517 2.00 0.99–4.040.0630 1.75 0.97–3.230.1353 1.93 0.81–4.620.2820 1.43 0.75–2.700.5990 1.19 0.63–2.22

Table 4Occurrence of relapse on/off medication after the first 5-year remission of seizures in adults with childhood onset epilepsy on 45-year follow-up bylearning disability

LD N n % P OR 95% CI

Occurrence of LD 0.0007No LD 52 16 30.8 1.0Any LD 123 72 58.5 3.17 1.59–6.33

Retarded (IQ < 71) 50 36 72.0 0.0091Mild (IQ 50–70) 7 2 28.6 1.0Severe (IQ < 50) 43 34 79.1 9.44 1.57–56.95

Nonretarded 73 36 49.3 0.3838Mentally normal 54 25 46.3 1.0Mentally near-normal 19 11 57.9 1.59 0.55–4.59

Retarded vs nonretarded 0.0112 2.64 1.22–5.70

Table 35-Year remission ever of seizures on/off medication in adults with childhood-onset epilepsy on 45-year follow-up by learning disability

LD N n % Probability of relapse OR 95% CI

Occurrence of LD 0.0003No LD 58 52 89.7 4.30 1.75–10.56Any LD 184 123 66.8 1.0

Retarded (IQ < 71) 93 50 53.8 0.4811Mild (IQ 50–70) 11 7 63.6 1.59 0.43–5.84Severe (IQ < 50) 82 43 52.4 1.0

Nonretarded 91 73 80.2 0.7366Mentally normal 68 54 79.4 1.23 0.36–4.20Mentally near normal 23 19 82.6 1.0

Nonretarded vs retarded <0.0001 3.49 1.81–6.73

M. Sillanpaa / Epilepsy & Behavior 5 (2004) 937–944 941

patients with IQs less than 50 compared with thosewhose IQ was 50 or greater.

A 5-year terminal remission was significantly morecommon in the mentally retarded subjects than in theretarded subjects (OR = 5.21, 95% CI = 2.20–12.33,P < 0.0001), as well as in patients with no LD comparedwith the learning disabled (3.06, 1.35–6.94, P = 0.0045).Similarly, a 5-year terminal remission without medica-tion was more common among the mentally nonre-tarded subjects (8.55, 3.43–21.28, P < 0.0001) andamong those with no LD (3.91, 1.89–8.09, P = 0.0001).

3.4. Social outcome

Eleven percent of the patients with LD but normalintelligence and 33% of those with near-normal intelli-gence were pensioned for employment disability(P = 0.0214). One percent of mentally normal and 10%of mentally near-normal subjects were independent(P = 0.0960). Among mentally retarded people, depen-dency in daily activities increased significantly(P = 0.0001) with decreasing mental level: of patientswith mild, moderate, severe, or profound mental retar-dation, 11, 20, 60, and 100%, respectively, were com-pletely or virtually completely dependent in activitiesof daily living. The corresponding figures for occasionalor permanent institutionalization were 20, 53, 81, and95%.

One-fourth of controls but almost half the subjectswith uncomplicated epilepsy but normal intelligenceand almost 90% of those with near-normal intelligencehad had to settle for primary education only or less thanprimary education (Table 5). The risks of unemploy-ment, living single, and having no children were higheramong near-normal than normal subjects. Except forone person who had a special college education, noneof the mentally retarded subjects, though not exemptedfrom compulsory education, could pass the matricula-tion examination. The lower the intelligence level, thegreater the risk of not passing. The same trend couldbe seen throughout the line: the intellectually less advan-taged had in fewer cases vocational training, paid work,a partner, or children. Interestingly, roughly the samepercentages of controls and subjects with epilepsy onlypassed the matriculation examination. Similarly, socio-economic status did not significantly differ between thetwo groups.

4. Discussion and conclusions

In our population-based, unselected study, 76% ofsubjects had at least one mild to severe learning disabil-ity. Half of the patients had MR, and the other half,near-normal to normal intelligence. The criteria appliedfor LD were fairly strict and the results are based on sev-

Table 5Social outcome of patients with epilepsy and learning disability compared with controls

Variable intelligence level Controls Age >85 Age 71–85 Age <70

N(%) N(%) P RR(95% CI)

N(%) P RR(95% CI)

N(%) P RR(95% CI)

Primary education only 23(23) 42(47) 0.001 2.03(1.33–3.09)

18(86) <0.001 3.69(2.48–5.49)

61(98) <0.001 4.23(2.96–6.07)

Failure to pass matriculationexamination

74(75) 69(78) 0.733 1.04(0.88–1.22)

21(100) 0.006 1.34(1.19–1.50)

62(100) <0.001 1.34(1.19–1.50)

No vocational training 51(52) 59(66) 0.054 1.29(1.01–1.64)

20(95) <0.001 1.85(1.49–2.29)

62(100) <0.001 1.94(1.60–2.35)

Unemployed 8(8) 26(28) <0.001 3.39(1.62–7.10)

13(59) <0.001 7.09(3.35–15.0)

63(100) <0.001 12.0(6.18–23.30)

Not living with partner 10(10) 29(32) <0.001 3.12(1.61–6.04)

15(68) <0.001 6.75(3.51–12.97)

63(97) <0.001 9.59(5.32–17.30)

No children 16(17) 41(45) <0.001 2.65(1.60–4.37)

20(95) <0.001 5.65(3.58–8.93)

65(100) <0.001 5.94(3.80–9.28)

No driver�s license 11(11) 32(35) <0.001 3.13(1.68–5.84)

11(52) <0.001 4.71(2.36–9.40)

63(100) <0.001 9.00(5.15–15.71)

Lower socioeconomic status 51(52) 57(62) 0.188 1.20(0.94–1.54)

20(95) <0.001 1.85(1.49–2.29)

62(100) <0.001 1.94(1.60–2.35)

942 M. Sillanpaa / Epilepsy & Behavior 5 (2004) 937–944

eral successive examinations including face-to-face inter-views and clinical examinations. Patients with epilepsyare generally considered to be at a threefold risk for cog-nitive or other mental problems [31]. Our results are inkeeping with these data. In another study of ours in1987, all the parents of children aged 8 to 9 years fromordinary schools in the same area as the study patientsreported one or more LDs in 15–20% and their teachersin 31% (unpublished data). Interestingly, the LD ratewas exactly the same in a recent study of 11-year-oldschoolchildren in the same city [32]. A specific LD hasbeen reported in 10 to 21% of adults with TLE [33].The figure is essentially the same as in our patients withuncomplicated epilepsy of any type. Of specific LDs,reading disability occurred in our sample significantlymore often in subjects with West syndrome or Len-nox–Gastaut syndrome, but significantly less often insubjects with rolandic epilepsy compared with other epi-lepsy types. Speech difficulties are known to be associ-ated with epilepsy-[34] related LD either transiently orconstantly [35–37]. In our study, the risk associated withuncomplicated epilepsy was 2.7-fold.

Reasons for LD among patients with epilepsy areprobably the direct effects of seizures, particularly inchildren with early age of onset, processes behind theepilepsy syndrome, effects of concomitant and often pre-ceding neuropsychological deficits, adverse effects ofdrug therapy, and social stigma [38]. A less favorable so-cial outcome of mentally near-normal may be preferablyexplained by a virtually lower performance potential.However, one cannot exclude the possible effect of socialstigma on the less successful future of mentally normaladults with uncomplicated epilepsy in childhood. Socie-tal misunderstanding and generalization of all peoplewith epilepsy as the same [39] by families [40], educators

[41], other people with epilepsy [42], and even patientsthemselves have though unintended, effects such as so-cial and educational displacement and omission. Our re-sults might indicate this effect; more subjects thanexpected had a compulsory primary education only,but if they did proceed with education, they passed thenext academic step, the matriculation examination, vir-tually as often as controls. Epilepsy is a stigma in Wes-tern societies [43,44], and an invisible handicap is aneven more labeling factor [45]. Epilepsy and LD posea challenge for our time to minimize the effects of boththe medical and social disadvantages of epilepsy [34].

Our study is one of the few population-based analy-ses of LD among both mentally retarded and mentallynormal or near-normal patients with epilepsy. The per-centage of mentally retarded in the present study(38%) is well in line with the previous studies (range,33–54%) [11,12,15–18,46]. MR was more commonamong our patients with prevalent cases (55%) thanamong those with incident cases (25%) [22]. The figuresof Camfield et al. [23], which were lower than those inthe previous studies and in our study both for mentalretardation and LD among children with normal intelli-gence, are explained largely by their different study pop-ulation. Furthermore, in the Camfield et al. study, theyoungest patients might have been too young for assess-ment, and the actual LD rate might therefore be higher.

The present study demonstrates a relationship be-tween low cognitive function and poor seizure outcome.Although some authors have not found any difference inoutcome related to the severity of intellectual disability,several others have reported such a relationship[3,5,6,15,16,22,47,48]. An association of cerebral palsywith epilepsy increased the prevalence of mental retarda-tion up to 41% in our patients. Similar figures (38–43%)

M. Sillanpaa / Epilepsy & Behavior 5 (2004) 937–944 943

have been reported [3,11,12,17,49,50]. The risk of the co-occurrence of LD with epilepsy increases with increasingseverity of cognitive deficit. However, in our subjectswith normal intelligence (IQ > 85), LD was more com-mon than in controls. The same observation has been re-ported both in adults [51] and in children [52,53], whosememory function in particular has been vulnerable.

In line with our study, early age at onset of epilepsy isan indicator of poor seizure outcome in LD, particularlyin severe LD [50,54]. Furthermore, the higher rate of re-lapses in patients with MR than in the mentally normalwas confirmed [18,22,48,55].

Social and educational outcomes are affected by LD.Less basic and vocational education, fewer marriagesand children, higher rate of disability pension for unfitto work, and higher rate of institutionalization have alsobeen reported in previous studies [18,56]. Intellectualdeficits are of greater importance than personality dis-turbances in social adjustment [48].

In conclusion, learning disability is a common featureof patients with childhood-onset epilepsy of any kindand affects medical, social, and educational outcomes.Poor seizure outcome and learning disability occur moreoften than expected in epileptic subjects who are men-tally normal, followed by mentally near-normal andmentally retarded subjects. Although the social conse-quences may be in part related to social stigma, thereis no doubt that biological factors play an importantrole in adjustment and social accomplishment. Futureprospective population-based studies should be designedto evaluate how much the causative factors differ be-tween these subgroups and how well progress in moderndiagnostic technology and antiepileptic drug develop-ment and improvement in public attitudes may decreaselearning problems in people with epilepsy.

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