Reaction Time, Attention, and Impulsivity in Epilepsy W e n d y G. M i t c h e l l , MD**, Y v o n n e Z h o u , M S t , J o h n M. C h a v e z , PhD*, and B i a n c a L. G u z m a n , BA*

Reaction time, attention, and impulsivity were studied in 112 children with epilepsy (4.5-13 years) using a computerized test. We measured simple reaction time (response with each hand separately to a single stimulus), forced choice reaction time (two stimuli presented in random order, one designated for each hand), and choice reaction time with distraction (two response stimuli, one for each hand, with two additional distracting stimuli randomly inserted). We also measured variability of speed of response and errors of omission and commission. Controls were unaffected children of similar age, ethnic, and socioeconomic backgrounds. Children with epilepsy were significantly slower, more variable, and made more omission errors than control children, even when analysis was limited to epileptic patients with IQ > 90, but they did not make more commission (i.e., impulsive) errors. Reaction times were related to IQ, but in general were not related to seizure severity, duration of seizure disorder, or duration of medication use. Untreated patients (N = 13) did not differ from those with antiepileptic drug levels in the therapeutic range on the day of testing (N = 52), but differed significantly from normal patients. Epileptic patients demonstrated significant slowing of reaction time and inattention, but not significant impulsivity, compared to normal children; however, these deficits do not appear to be related specifically to seizure history or treatment. Mitchell WG, Zhou Y, Chavez JM, Guzman BL. Reaction time, attention, and impulsivity in epilepsy. Pediatr Neurol 1992;8:19-24.

Introduction A variety of cognitive and attentional processes may be impaired in children and adults with epilepsy. Nonspecific difficulties, such as poor academic progress [1-3], behavioral problems [4], poor memory [5], and low IQ scores [6] are widely reported, but more detailed evaluations of

From the *Department of Neurology and 1Division of Biometry, Department of Preventive Medicine; University of Southern California School of Medicine; and the *Division of Neurology; Children's Hospital Los Angeles; Los Angeles, California. Presented in part at the American Academy of Neurology Meeting, Cincinnati, April, 1988.

specific mechanisms of impairment are rarely available. There is no consensus regarding the association of various seizure-related variables with these impairments. Contradictory evidence exists regarding the importance of seizure type, seizure severity, lifetime seizure experience, and detrimental or beneficial effects of a variety of specific medications or treatment protocols [7-10]. It is unclear whether the learning, behavior, and cognitive problems are the result of the seizures, the result of treatment, or simply coexist without a specific causative relationship. A recent review of the effect on neuropsychologic function of seizure-related variables (i.e., severity, age at onset, seizure type, treatment) emphasizes the lack of consistency across the many available studies, in both methodology and results [ 11]. In adults with epilepsy treated with phenytoin, Dodrill and Tempkin reported that the apparent dose-related cognitive impairment by phenytoin was due to an impairment of motor speed. When simple motor speed (finger tapping) was factored out in the analysis, cognitive impairments attributed to high phenytoin concentration were no longer evident [12]. This finding may apply to other studies of epilepsy. Several subscales of most standard cognitive measures involve timed motor tasks. Lower IQ score may simply reflect a relatively minor slowing of either cognitive processing, motor speed, or both. Smith et al. studied untreated adult epileptics and found extensive deficits compared to normal adults, with particular differences in motor speed, attention, and reaction time [13]. Deficits in sustained attention are often reported in children with epilepsy. In clinical settings, attention is generally measured using either parent and teacher questionnaires (e.g., Conner's scales) [14] or by use of groups of specific subscales of standardized psychometric tests. The Freedom from Distractibility score on the Wechsler Intelligence Scale for Children-Revised (WISC-R), for example, compares subscale scores for arithmetic, digit span, and coding with overall scores [15]. Specific psychometric tests have been devised to look at impulsivity and attention, such as the Kagan Matching Familiar Figures Test (MFFT) [16]. All of these methods approach the assess-

Communications should be addressed to: Dr. Mitchell; Neurology Division- Box 82; Children's Hospital Los Angeles; P.O. Box 54700; Los Angeles, CA 90054. Received May 9, 1991; accepted July 9, 1991.

Mitchell et al: Epilepsy

19

ment of attention differently and all have specific shortcomings. It is difficult to discriminate the child with attention deficit from the child with an emotionally based conduct disorder using the questionnaires. Two subscales of the WlSC-R used to calculate the Freedom from Distractibility are timed tests, sensitive to impairments of either motor speed or mental speed, and consequently potentially provide information that would confound the evaluation of attention in a child with epilepsy. The child with slowing of motor or mental speed may do poorly on these timed subscales, especially in comparison to the untimed verbal subscales, and be erroneously judged as distractible. The MFFF primarily detects impulsivity. The inattentive child who is not impulsive will not be detected by the MFFT. Computerized testing offers an alternative to conventionally administered psychometric testing. Computerized testing can be designed to be repeatable, reproducible, and with known or controllable practice effects. A number of investigators have used computerized test batteries to study basic processes, such as reaction time, choice reaction time (combining motor speed and mental speed), and sustained attention. Differences between normal controls and patients with epilepsy have been found by a number of authors. Brodie et al. compared adults with epilepsy, both treated and untreated, to normal adults [17]. He found that the untreated epileptics had slower choice reaction times and finger tapping than normal adults. Hara used a continuous performance test to study attention in children with epilepsy [ 18]. He compared both untreated and treated children with epilepsy or febrile seizures to normal children matched for mental age. Treated patients were on a variety of antiepileptic drugs; approximately 60% were on monotherapy, 40% on polytherapy. Both groups of children with seizures made more errors than normal children. Treated and untreated groups did not differ. He concluded that children with epilepsy have an impairment of attention that is not a treatment effect. Other investigators reported substantial effects of antiepileptic drugs on tests measuring reaction time, mental speed, and vigilance. For example, Dekaban and Lehman studied adults with epilepsy while either increasing or decreasing antiepileptic drug doses [19]. They found that higher medication doses affected reaction time and vigilance. Conversely, Smith et al. reported minimal differences between test results before and after beginning treatment in adult epileptics [13]. Cull and Trimble used a computerized battery of mental function tests to assess children with epilepsy while either increasing or decreasing antiepileptic drugs [20]. They found that increasing antiepileptic drug doses lengthened response latency for complex mental processing tasks, but decreasing antiepileptic drug doses did not improve performance; however, their samples were very small and patients were on a variety of different medications. In order to further investigate attention in children with epilepsy, we developed a computerized test formatted as a videogame. In contrast to other reported computerized

20

PEDIATRIC NEUROLOGY

Vol. 8 No. 1

tests we used colored shapes, rather than letters or numbers as the stimuli. We previously reported significant differences between groups of normal and hyperactive elementary school children in simple, choice, and complex reaction times and both omission and commission errors using this test [21]. We asked whether children with epilepsy differ from normal children in reaction time, attention, and impulsivity: whether the differences reflected general cognitive delays (i.e., explained by low IQ); and whether impairments related to seizure history (i.e., severity, duration) or antiepileptic drug therapy.

Methods The test is described in detail elsewhere [21]. Although much simpler than most videogames, the group of tests was described to the patients as a game on which they could earn points. The first test was extremely simple; subsequent tests were progressively more complex. The tests included simple reaction time, forced choice reaction time, and choice reaction time with distraction (referred to as complex reaction time below). The entire test took 20-30 min, depending upon the child's speed and accuracy. The stimuli were colored shapes. Each covered the same total screen area and had a maximum horizontal width of 5 cm. The child's responses were simple (pushing a button with the right or left hand). Each test required a brief explanation, but basically was self-taught in a brief practice session. The child was instructed to respond as fast as possible. For the first test, (simple reaction time) the child was given a single button, mounted in a bicycle grip, and instructed to push the button when a red square appeared on the screen. The dominant hand was tested first, followed by the nondominant hand. For subsequent tests, similar buttons were placed in each hand. The child was instructed to push the button in the dominant hand when they saw a red square and the button in the nondominant hand when they saw a blue star. For complex reaction time (choice with distraction), they also were instructed that when a blue square or red star appeared that they were not to push any button. Patients were rewarded with an inexpensive toy at the conclusion of the test. Stimuli appeared at randomly varying intervals within a specified minimum and maximum. A response delayed over 5 sec was recorded as an omission error. The child must have responded to the specified number of stimuli with the correct hand to complete the test. Thus, a child with numerous omission or hand errors would have been exposed to more total stimuli because the incorrect or omitted stimuli did not contribute to the total number of scored response times. A correct Table 1.

Scores collected

Test

Scores

Simple reaction time

Median reaction time, each hand Variability (mean deviation reaction time) Omission errors

Choice reaction time

Median reaction time, each hand Variability (mean deviation reaction time) Omission errors Hand errors (wrong response to target)

Complex reaction time

Median reaction time, each hand Variability (mean deviation reaction time) Omission errors Hand errors (wrong response to target) Commission errors (response to nontarget)

response generated an immediate multicolored "happy face" and tone. Incorrect responses generated a different tone and a message across the screen. Anticipatory responses also generated a tone and a screen message, and prevented the appearance of the next stimulus until the patient released the button. Scores collected are listed in Table 1. Scores include median response time (MRT) for each hand and each test, a variability score (MDRT) for each test, omission errors for each test, hand errors for choice and complex reaction time tests, and commission errors (response to a distraction stimulus) during the complex reaction time test. Median response time is used rather than mean because of insensitivity to outlying values. The variability score and the omission errors are primarily sensitive to the ability to sustain attention; the hand errors and commission errors are measures of impulsivity.

Patients Epilepsy Group. School-aged children (41/2-13 years) who presented to the Seizure Clinic at Children's Hospital of Los Angeles were enrolled in a study of psychosocial and cognitive consequences of childhood epilepsy. Patients were tested at the first clinic visit or on a separate visit for psychometric testing within 2 weeks of enrollment. Patients included both untreated and chronically treated patients with seizure histories ranging from days to years. Patients were from all ethnic and socioeconomic groups, with a predominance of poor, inner city, minority families. In addition to the videogame, cognitive, academic, and behavioral data were collected. Patients were excluded when their IQ scores were less than 65, had significant motor or sensory deficits interfering with testing, or spoke neither English nor Spanish. Virtually all eligible patients consented to enroll in the project. Normal Group. Normal subjects were studied in 2 local elementary schools. Teachers of kindergarten through sixth grade identified potential subjects and sent home consent forms. Teachers were asked to screen out any child who had been retained in a grade, enrolled in any remedial or special education program except English-as-a-second-language, referred for evaluation of hyperactivity or attention deficit, or who was known to have epilepsy or other chronic illnesses. The parent consent form contained a brief questionnaire. Patients were excluded if parents reported that they were taking any centrally active medication (e.g., antiepileptics, stimulants, antihistamines, theophylline), had epilepsy, or had been evaluated or referred for attention deficit or hyperactivity. Although specific data on socioeconomic status was not collected, the 2 schools represent a mixed community, including both low income, minority households and a middle class, primarily nonHispanic caucasian community. Normal subjects were tested over a period of 2 months at their schools. They were taken from the classroom and asked to "play a game" in order to "win a prize." All children agreed. The test was administered in a small private office at the school, similar in size and furnishings to the testing area of the clinic.

Other Testing The epileptic patients underwent cognitive testing using either the WISC-R [22] or the McCarthy Scale of Children's Abilities [23]. For purposes of this study, the general cognitive index (GCI) on the McCarthy scale was considered comparable to the full-scale IQ on the WISC-R for use in establishing a subgroup of epileptic patients with normal cognitive abilities. The McCarthy GCI and the WlSC-R IQ both have a mean of 100 in a normal population, but have slightly different S.D.: 16 for the GCI compared to 15 for the WISC-R IQ. The correlation between WISC-R IQ and GCI is very high [24]. Seizure variables included overall seizure severity, duration of seizure disorder, and total medication exposure. Each was recorded at the child's first visit to the clinic. Patients with "mild" seizures included those with only a single episode of convulsions, or less than 1 convulsion per year; those with partial seizures occurring less than monthly, and those with occasional (not daily) absence seizures. Patients with

"severe" seizures had either more frequent seizures of a single type or had multiple seizure types. When available, antiepileptic drug serum levels were recorded on the day of the test.

Data Analysis All test results were uploaded from the Apple lie ® microcomputer to an IBM 3081 mainframe computer. The data were read into a biostatistical analysis program, Statistical Analysis System (SAS, SAS Institute, Cary, NC). A median reaction time (MRT) for each patient for each test was calculated from the raw reaction times. The mean deviation of the response times (MDRT) was used as a measure of variability of responses. It was calculated using the following formula: sum I RT-MRT I MDRT = N Because a linear relationship was found between age and log of the MRTs and MDRTs, all MRTs and MDRTs were transformed to natural logs for further analysis, and then backtransformed for interpretation. Omission errors, hand errors, and commission errors were calculated as simple counts. The normal group was compared to the epilepsy group using t tests to examine continuous variables and chi-square or Wilcoxon 2-sample tests to examine categorical variables. Analysis of covariance was used for within-group comparisons of epileptic patients due to the different age distributions between the subgroups. The relationship between each test score and IQ was examined in the epilepsy group using linear regression. Although the normal group did not have cognitive testing, exclusion criteria would have eliminated any child with borderline or mildly retarded cognitive function; therefore, so as not to confuse generalized cognitive delays with more specific deficits in attention and reaction time, comparisons between the normal patients and the children with epilepsy were restricted to epileptic patients whose IQ scores were above 90 (EIQ>9O) and an agematched group of normal subjects. Detailed demographic information was available for the epileptic, but not the normal subjects. To be certain that ethnic, racial, or sociodemographic differences did not confound results, we analyzed scores of epileptic patients for the effects of race, ethnicity, family income, and mother's education. None of these factors had a significant influence upon test scores in the EIQ>90group.

Results

Between Group Comparisons: Normal versus Epileptic. The 52 epileptic patients with IQ scores greater than 90 (EIQ>90) were compared to 52 age- and sex-matched normal subjects. Median age was 102 months and 54% were male. Mean IQ of EIQ>90 was 101 (range: 91-124). As noted, IQ was not available on normal subjects. The EIQ>90 group differed significantly from the normal group on all reaction times (MRTs) except simple reaction time for the dominant hand. Differences between the normal and EIQ>90 groups were greater for the nondominant than the dominant hand. Differences for the dominant hand are statistically marginal, while those for the nondominant hand are significant (P < .01) for all measures. Variability (MDRT) was greater in epileptic patients for choice and complex reaction times, at highly significant levels (P < .01). The EIQ>90 group made more omission errors on simple and complex reaction time tests and more total omission errors. Hand errors and commission errors did not differ on any test segment (Table 2). Within Group Comparisons: Epileptic Patients. We compared patients with the mildest seizures to those with

Mitchell et al: Epilepsy

21

Table 2. Comparison of normal subjects and EIQ>90patients* Speed and Variability (msec) Epileptic P Controls Patients Values Simple Reaction Time

Dominant hand

260

300

NS

Nondominant hand

250

330

.01

65

77

NS

Dominant hand

560

670

.04

Nondominant hand

650

820

.003

Variability

142

190

.007

Dominant hand

825

985

.02

Nondominant hand

985

1,200

.007

Variability

226

238

.008

Variability Choice Reaction Time

Complex Reaction Time

Error Scores (counts)

Omission errors, simple RT

0

1.06

.04

Omission errors, choice RT

1.02

1.05

NS

Omission errors, complex RT

1.11

1.57

.009

Total omission errors

1.33

1.95

.004

Hand errors, choice RT

2.64

2.65

NS

Hand errors, complex RT

1.18

1.24

NS

Total hand errors

3.12

3.27

NS

Commission errors, complex RT

2.5

2.8

NS

* N=52. Abbreviations: NS = Not significant RT = Reaction time

the most severe. There were no differences in sex, age, or IQ distribution between those with the mildest and those with the most severe seizure histories. Although patients with milder seizures tended to do better on all 3 tests, significant differences were few and generally o f marginal statistical significance (P = .01-.05). Seizure severity was significantly related only to M D R T (variability) on choice and complex reaction time tests and nondominant hand choice reaction time (Table 3). Duration of seizure history also was examined. Although patients with short duration of seizures performed slightly better on most measures, the only statistically significant difference between patients with short versus long seizure histories was better performance by those with longer seizure histories: commission errors on complex

22 PEDIATRIC NEUROLOGY Vol. 8 No. 1

reaction time test, at marginal statistical significance ot P = .05 (Table 3). Total medication exposure (number o! antiepileptic drugs used by total time of use) was related to complex reaction time, variability, and omission errors on test 3. and omission errors on test 2, with small but statistically significant differences between patients with less than 1 month of total medication exposure and those treated with antiepileptic drugs for over 1 year. Statistical significance is marginal (P = .01-.05) with the exception of omission errors on test 3 (P < .01; Table 3). On the day of the test, 62 patients were receiving antiepileptic drugs, confirmed by serum antiepileptic drug levels within the therapeutic range; 13 were not currently on medications. The remaining 37 patients either did not have a concurrent antiepileptic drug level or had recently had medication doses changed. These patients were ex.cluded from this analysis. Age, sex, and IQ statistics were similar between the 2 groups. Only MDRT (variability) on test 1 was significantly different, with patients on medication being less variable than those who were not treated (Table 3). The subgroups with mild seizures, short duration, and minimal antiepileptic drug exposure were compared to the normal patients, covarying when necessary by age. Highly significant differences were found between these epileptic patients and normal subjects for all MRT and MDRT measures and for most error scores. The small group of 13 unmedicated epileptic patients differed from normal subjects on all speed and variability measures and in omission errors in tests 2 and 3 (choice and complex reaction time), but not in impulsive (commission and hand) errors. Differences in MRTs were highly statistically significant (P < .0001). We examined the effects of IQ on test scores in the epileptic patients. IQ affected the ability to complete the more complex tests. All of the normal subjects and EIQ>90 patients completed all segments, but among 60 low IQ epileptic patients (IQ range: 65-90), only 46 completed the most difficult test (complex reaction time). There were highly significant negative correlations between each of the age-adjusted reaction time and variability scores and IQ; error scores were not consistently related to IQ.

Discussion

Epileptic patients with normal intelligence differed markedly from normal peers in reaction time and attention, but not impulsivity. Differences were consistently greater for nondominant hand speed than for dominant hand. Cognitively impaired epileptic patients (IQ range: 65-90) had even more impairment on reaction time measures. Differences between children with very mild seizures (generally a lifetime total of only 2-5 generalized seizures or infrequent partial seizures) and those with more frequent, more severe, or longstanding seizure disorders were small, with few reaching statistical significance. Even pa-

Table 3.

Relationship of seizure severity, duration, and treatment to scores Seizure Severity Mild Severe

Number Age (median; years)

36 8.8

58 8.4

Seizure Duration Short Long

33 8.6

61 8.5

Medication Duration Short Long

54 8.6

40 8.5

Current Medications None Any

13 7.8

62 8.5

Test 1: Simple Reaction Time

MRT (Dom; msec)

290

380

340

380

340

390

380

350

MRT (Nondom; msec)

290

440

360

440

360

440

580

360

72

84

78

82

78

80

182

72*

0

2.6

MDRT (msec) Omission error

0.19

0.32

0.27

0.27

0.17

0.41

Test 2: Choice Reaction Time

MRT (Dom; msec)

640

790

640

760

700

840

740

740

MRT (Nondom; msec)

700

920*

760

840

800

870

840

810

MDRT (msec)

136

248*

154

220

164

282

246

172

Omission error

0.11

0.74

0.25

0.64

0.19

0.93'

0.38

0.52

Hand errors

2.2

2.9

2.75

2.62

2.49

2.9

1.52

2.89

Test 3: Complex Reaction Time

MRT (Dom; msec) MRT (Nondom; msec) MDRT (msec)

960

1,180

960

1,130

960

1,200"

1,110

1,030

1,100

1,260

1,140

1,250

1,140

1,260"

1,140

1,220

344

394

344

440*

356

378

316

412*

Omission error

0.73

2.82

0.89

2.62

1.16

3.31 t

0.79

2.25

Hand errors

1.22

1.71

2.17

1.15

1.69

1.25

0.63

1.89

Commission

4.59

4.27

5.86

3.58*

4.59

4.09

2.64

5.02

*P = .05-.01. t p < .01. P values compare mild to severe seizures, long- to short-duration seizure history or treatment, and no medication to any medication in therapeutic range on day of testing.

Abbreviations: Dom = Dominant hand MDRT = Mean deviation reaction time

MRT = Median reaction time Nondom = Nondominant hand

tients w i t h the m i l d e s t s e i z u r e s o r the s h o r t e s t seizure history differed markedly from their normal peers on reaction t i m e s a n d v a r i a b i l i t y scores a n d o n s o m e e r r o r scores. D i f f e r e n c e s b e t w e e n t h e e p i l e p t i c s w i t h the m i l d e s t seiz u r e s a n d n o r m a l p a t i e n t s w e r e far g r e a t e r t h a n d i f f e r e n c e s b e t w e e n the m o s t a n d least s e v e r e e p i l e p t i c s a n d r e a c h e d statistical significance with adjustment for multiple comparisons. N o t e n o u g h p a t i e n t s w e r e a v a i l a b l e to e x a m i n e e a c h seizure type individually. W e c a n n o t a d d r e s s the issue o f w h e t h e r c h i l d r e n w i t h c o n v u l s i v e o r m i x e d s e i z u r e s diff e r e d f r o m t h o s e w i t h a b s e n c e or p a r t i a l s e i z u r e s w i t h t h e

s a m p l e size c u r r e n t l y a v a i l a b l e . D i f f e r e n c e s r e l a t e d to t r e a t m e n t h i s t o r y w e r e small, a l t h o u g h p a t i e n t s w i t h less total e x p o s u r e to a n t i e p i l e p t i c m e d i c a t i o n s t e n d e d to perf o r m b e t t e r t h a n p a t i e n t s w i t h g r e a t e r total e x p o s u r e ; h o w ever, t h e s m a l l u n m e d i c a t e d g r o u p d i d n o t differ f r o m p a t i e n t s o n a n t i e p i l e p t i c d r u g s o n the d a y o f the test. Our findings suggest that the slowed reaction times and i n a t t e n t i o n d e m o n s t r a t e d b y the e p i l e p t i c p a t i e n t s w e r e n o t p r i m a r i l y a r e s u l t o f t h e i r s e i z u r e s or t r e a t m e n t . W e a g r e e w i t h the f i n d i n g s o f H a r a w h o r e p o r t e d deficits in a t t e n t i o n in c h i l d r e n w i t h e p i l e p s y or f e b r i l e seizures [18]. H e also found no difference between patients receiving antiepilep-

Mitchell et al: Epilepsy 23

tic drugs (primarily phenobarbital) and those who were not treated. We conclude that children with epilepsy demonstrate abnormalities compared to their normal peers, particularly in reaction time. These differences are not solely reflective of overall cognitive impairment, although cognitively impaired epileptic children had more severe slowing of reaction times than those with normal intelligence. Slowed motor speed may contribute to a relatively low performance IQ score, in that the most commonly used IQ tests rely on timed measures for most of the performance subscales. We speculate that the seizure disorder and the slowed reaction time may be caused by similar or coexisting neurologic abnormalities, but that neither the seizures nor the treatment alone caused the slowed responses.

This study was supported by a grant from the Robert Wood Johnson Foundation. We thank Dr. Stanley Azen, University of Southern California School of Medicine, Department of Preventive Medicine, for his supervision of data analysis and biostatistics. We also thank Dr. Masato Takihashi, Children's Hospital, for his translation of Dr. Hara's article from Japanese. Computer programming and assistance in the development of the computerized tests was provided by Dr. Stephen Citron, Professor of Electrical Engineering, Purdue University.

References

[1] Bagley CR. Educational performance of children with epilepsy. Br J Educ Psychol 1970;40:82-3. [2] Seldenberg M, Beck N, Geisser M, et al. Academic achievement in children with epilepsy. Epilepsia 1986;27:753-9. [3] Holds'worth L, Whitmore K. A study of children with epilepsy attending ordinary schools; I. Seizure patterns, progress and behavior in school. Dev Med Child Neurol 1974;16:746-58. [4] Rutter M, Graham P, Yule W. A neuropsychiatric study in childhood. Clinics in developmental medicine 35/36. London: Spastics International Medical Publications, 1970; 175-210. [5] Farwell JR, DodriU CB, Batzel LW. Neuropsychological abilities of children with epilepsy. Epilepsia 1985;26:395-400. [6] Stores G. Problems of learning and behavior in children with epilepsy. In: Reynolds EH, Trimble MJ, eds. Epilepsy and psychiatry. Edinburgh: Churchill Livingstone, 1981;33-49. [7] Mitchell WG, Chavez JM. Carbamazepine versus phenobarbital for partial onset seizures in children. Epilepsia 1987;28:56-60.

24

PEDIATRIC NEUROLOGY

Vol. 8 No. 1

[8] Freeman JM, Tibbles J, Camfield C, Camtieid P. Bemgn ¢1~• lepsy of childhood: A speculation and its ramifications Pediatrics 1987;79:864-8. [9] Vining EPG, Mellits ED, Dorsen M, et ai. t'sychologJc and be. havioral effects of anticonvulsant drugs in children. A double blind comparison of phenobarbital and valproate. Pediatrics 1987;80:165-74. [10] Thompson PJ, Trimble MR. Anticonvulsant serum levels: Relationship to impairments of cognitive functioning. J Neural Neurosurg Psychiatry 1983;46:227-33. [11] Seidenberg M. Neuropsychologicat functioning of children with epilepsy. In: Hermann B, Seidenberg M, eds. Childhood epilepsies: Neuropsychological, psycbosocial and intervention aspects. Chichester: John Wiley and Sons, 1989"71-81. [12] Dodrill CB, Tempkin NR. Motor speed is a contaminating factor in evaluating the "cognitive" effects of phenytoin. Epilepsia 1989; 30:453-7. [13] Smith DB, Craft BR, Colins J, Mattson RH, Cranmr JA, VA Cooperative Study Group 118. Behavioral characteristics of epilepsy patients compared with normal controls. Epilepsia 1986;27:76(I-8. [14] Goyette CH, Conners CK, Ulrich RF. Normative data on revised Conners parent and teacher rating scales. J Abnonn Child Psychol 1978;6:221-36. [15] Kaufman AJ. Intelligent testing with the WISC-R. New York: John Wiley and Sons, 1979;70-8. [16] Kagan J. Reflectivity-impulsivity: The generality and dynamics of cognitive tempo. J Abnorm Psychol 1966;71 : 17-24. [17] Brodie MJ, McPhail E, Macphee GJ, Larkin JG, Gray JM. Psychomotor impairment and anticonvulsant therapy in adult epileptic patients. Eur J Clin Pharmacol 1987;31:655-60. [18] Hara H. Sustained attention and the influence of anticonvulsants on it in children with epilepsy or febrile convulsions. No To Hattatsu 1986; 18:387-98. [19] Dekaban AS, Lehman EJ. Effects of different dosages of anticonvulsant drugs on mental performance in patients with chronic epilepsy. Acta Neurol Scand 1975;52:319-30. [20] Cull CA, Trimble MR. Effects of anticonvulsant medications on cognitive functioning in children with epilepsy. In: Hermann B, Seidenberg M, eds. Childhood epilepsies: Neuropsycho!ogicall psychosocial and intervention aspects. Chichester: John Wiley and Sons, 1989; 83-1 (13. [21] Mitchell WG, Chavez JM, Baker SA, Guzman BL, Azen SP. Maturation of sustained attention in normal and hyperactive children: A videogame technique. J Child Neurol 1990;5:195-204. [22] Wechsler D. Manual for the Wechsler Intelligence Scale for Children-Revised. New York: Psychological Corporation, 1974. [23] Kaufman A J, Kaufman NL. Clinical evaluation of young children with the McCarthy scales. New York: Grune and Stratton, 1977; 17-28. [24] Arinoldo CG. Concurrent validity of McCarthy's scales. Percept Mot Skills 1982;14:1343-6.

Reaction time, attention, and impulsivity in epilepsy.

Reaction time, attention, and impulsivity were studied in 112 children with epilepsy (4.5-13 years) using a computerized test. We measured simple reac...
601KB Sizes 0 Downloads 0 Views