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Do hyperactive children and their siblings differ in IQ and academic achievement?
Psychiarry, Research, 6, 253-258 (1982) Elsevier
Biomedical
253
Press
Do Hyperactive and Academic
Children and Their Siblings Achievement?
Jeffrey
M. Halperin
Received
October 9, 1981; accepted
Differ
in IQ
and Rachel Gittelman December
12. 1981.
Abstract. To test the hypothesis that intellectual deficits are a trait shared by family
members of hyperactive children, 18 hyperactive children were compared to their nonhyperactive siblings on measures of intelligence and academic achievement. As measured by the Wechsler Intelligence Scale for Children, the nonhyperactive siblings had significantly higher Verbal, Performance, and Full Scale IQs. Scores on the Wide Range Achievement Test and the Gray Oral Reading Test did not differ between the groups when adjusted for IQ. Contrary to previous hypotheses, the data suggest that intellectual deficits may be specific to hyperactive children and not a familial trait. Key Words. Hyperactivity, demic achievement.
attention
deficit disorder, siblings, intelligence, aca-
Evidence exists suggesting that the syndrome of hyperactivity, now known as attention deficit disorder with hyperactivity (American Psychiatric Association, 1980) is associated with intellectual and academic achievement deficits. Palkes and Stewart (1972) reported that IQ scores on the Wechsler Intelligence Scale for Children (WISC) were significantly lower in children referred to a clinic and diagnosed as hyperactive than in controls selected from a neighborhood school. Another study (Minde et al., 1971) compared the IQ scores of hyperactive children seen 4 to 6 years earlier at an outpatient clinic to those of their classmates, using the Henman-Nelson Tests of Mental Ability. They also found that the hyperactive children had significantly lower IQ scores. Stewart et al. (1974) investigated differences between nonpatient hyperactive children and their nonhyperactive classmates. Using a teacher rating scale, they screened a large grade school population in a suburban school district for the presence of hyperactive children. They found that scores on the Lorge-Thorndike group intelligence tests for the children rated hyperactive (n = 22) were significantly lower than those of nonhyperactive classmates (n = 296). Despite the use of different subject selection procedures and different measures of intelligence, all three studies resulted in significantly lower IQ scores for hyperactive children as compared to controls. The group differences ranged from 10.5 to 12.4 IQ points. Academic achievement scores, as measured by the Wide Range Achievement Test (WRAT) and the Gray Oral Reading Test (GOR), have also been found to differ significantly between hyperactive children and normal controls. However, when
Jeffrey M. Halperin, Ph.D., and Rachel Gittleman, Ph.D., are at the New York State Psychiatric 722 W 168th St., New York, NY 10032, USA. (Reprint requests to Dr. J.M. Halperin.)
01651781/82/0000-0000/$02.75
@ Elsevier
Biomedical
Press
Institute,
254 achievement test scores were controlled for IQ, group differences disappeared (Palkes and Stewart, 1972). On the other hand, Minde et al. (197 1) matched hyperactive and nonhyperactive children for IQ and found the hyperactives to have significantly poorer school performance. Cantwell and Satterfield (1978) found no significant group differences in WRAT scores between hyperactive children and controls. However, they found that significantly more hyperactive children were underachievers based on the expectation for their age and IQ. The literature strongly suggests that hyperactive children’s intellectual abilities are significantly compromised. This deficit may be a function of their behavioral disorder, which could interfere with test performance, or due to a different, possibly related factor, such as minimal brain dysfunction. In either case, the deficit is specific to the hyperactive child. An alternative hypothesis, proposed by Stewart et al. (1974), posits that the intellectual deficit is not specific to hyperactive children, but rather a trait shared by their family members irrespective of the presence of hyperactivity. This hypothesis is supported by data obtained from a study of nonhyperactive siblings of hyperactive children whose intellectual functioning was compared to that of two groups: (1) their own hyperactive siblings (Stewart et al., 1974) and (2) siblings of a normal control group (Welner et al., 1977). No differences in IQ were found between the hyperactive children and their nonhyperactive siblings. However, the brothers of the hyperactive children were found to have significantly lower scores (6-point difference) than the brothers of controls on the WISC Verbal and Full Scale IQ. No significant IQ score differences occurred between the sisters of hyperactives and controls. Surprisingly, academic achievement scores, when controlled for IQ, were significantly higher in the siblings of the hyperactive children than in the siblings of controls. The interpretation that the above findings indicate intellectual deficits to be a familial trait of hyperactive children is open to question. The hyperactive children in these reports were also reported to have high levels of antisocial behavior, such as stealing (44% of them) and running away. This suggests that many of the patients could have been diagnosed more accurately as having conduct disorders rather than hyperactivity or in conjunction with it. Since children diagnosed as conduct disorders appear to differ from hyperactive children with regard to IQ (Sandberg et al., 1978; Stewart et al., 1981), the study of IQ decrements in hyperactive children requires careful diagnostic definition. To assess whether hyperactive children and their siblings differ in intellectual functioning, WISC IQ scores of objectively defined hyperactive children were compared to those of their nonhyperactive siblings. The hyperactive children did not have concurrent conduct problems as measured by the Conners Teacher Rating Scale (Conners, 1969), and by psychiatric evaluation. In addition, the groups’ WISC subtest scores and their achievement scores on the WRAT (Jastak and Jastak, 1965) and the GOR (Gray, 1967) were compared. Correlations between the scores of hyperactive children and those of their siblings on the WISC, WRAT, and GOR were obtained.
Method Subjects. The subjects in this study were 18 drug-free hyperactive children and 21 of their siblings. The subjects were primarily lower middle class Caucasians from a residential area in
255 New York City. The hyperactive children were a subsample of children who participated in a study previously reported (Gittelman-Klein et al., 1976). The original sample was composed of children who were rated as hyperactive in school according to the Conners Teacher Rating Scale (Conners, 1969), and were also reported to be hyperactive at home or in the clinic. These criteria are described in greater detail in Gittelman-Klein et al. (1976). Other entry criteria to the original study were that the children: (1) be between 6 and 12 years old; (2) be attending school; (3) be free of neurological disease; (4) be nonpsychotic; (5) obtain a Full Scale WISC IQ of at least 80, and either a Verbal or Performance IQ of at least 85; and (6) have no previous history of clinically significant psychopharmacological treatment. The subsample studied in this report were those from a part of the original sample who (1) were found to have no signs indicating the presence of a conduct disorder, as defined by a rating of “yes” or “maybe” on the unsocialized or socialized aggressive items of the Children’s Diagnostic Classification (ECDEU, 1973), and (2) had siblings ranging in age from 6 to 12 years old who were of the same sex as the probands, and were not reported to have any behavior difficulties in school. The hyperactive group comprised 17 boys and 1 girl, and the siblings included 20 boys and 1 girl. The mean ages of the hyperactive group and their siblings were 8 years, 6 months, and 9 years, 3 months, respectively (p > 0.10). Procedures. All children were administered the WISC, WRAT, and GOR. The two groups were compared, using two-tailed I tests, to see if they differed in IQ, WISC subtest scores, and achievement scores. The achievement score differences were contrasted further, controlling for
IQ. Pearson correlation coefficients were determined between the scores of the hyperactive children and their nonhyperactive siblings on the WISC, WRAT, and GOR. To pair the groups for the correlation, the sibling closest in age to the hyperactive child was used in cases in which there was more than one sibling.
Results Table 1 shows the factor scores for the 18 hyperactive children on the Conners Teacher Rating Scale. Scores on the conduct problem factor are significantly @ < 0.00 1) lower than those for the inattention and hyperactivity factors.
Table 1. Factor scores for hyperactive Conners Teacher Rating Scale1 Factor 1. Conduct
problems
children
Mean
SD
on the
1.02
0.56
Il. Inattention
1.76
0.47
Ill. Anxiety
0.55
0.56
IV. Hyperactivity
2.23
0.45
-1.26
0.78
V. Health 1, Scale range from 0 to 3
As shown in Table 2, both groups had WISC IQ scores within normal limits. The siblings, however, had significantly higher Verbal, Performance, and Full Scale IQ scores. Analyses examining differences between the two groups on the individual subtests revealed that similarities, vocabulary, digit span, and coding differed significantly (see Table 3).
256
Table 2. IQ and achievement hyperactive siblings
scores for hyperactive
children
and their non-
Group Hyperactive (n = 18) Measures Verbal
IQ
Performance
IQ
Siblings (n = 21)
Mean
SD
Mean
SD
t
P
99.0
12.2
111.7
12.7
3.78
0.003
98.8
12.5
108.3
11.4
2.48
0.02
Full Scale IQ
98.9
11.1
111.1
10.6
3.50
0.001
WRAT-Reading1
93.4
11.8
108.4
17.9
3.05
0.0042
WRAT-Spelling1
91.9
9.4
101.3
19.2
1.89
0.072
WRAT-Arithmetic1
93.2
9.5
99.0
9.7
1.86
0.072
GORs
-1.4
1.2
-0.5
2.3
1.41
NS2
1. Standard scores. 2. Not significant when corrected for IQ.
3. Difference between grade score and expected grade for age
Table 3. WISC subtest scaled scores for hyperactive nonhvoeractive siblinas
children
and their
GrOUD
Hyperactive Subtest Information Comprehension Arithmetic
(n = 18)
Siblings (n = 21)
Mean
SD
Mean
SD
t
9.33
2.11
11.10
3.22
1.98
0.06
10.44
2.90
10.95
2.16
0.65
NS
P
9.83
3.00
11.10
2.19
1.52
NS
Similarities
11.11
3.50
13.24
2.66
2.15
0.04
Vocabulary
9.78
2.80
12.33
2.11
3.25
0.002
Digit span
9.28
2.27
11.67
2.83
2.87
0.007
Picture
9.78
2.46
10.48
3.44
0.72
NS
Picture arrangement
10.89
2.87
12.38
2.56
1.72
0.09
Block design
10.33
2.38
10.71
2.65
0.47
NS
Object
10.22
3.44
11.71
2.51
1.56
NS
7.94
2.18
10.62
2.60
3.45
0.001
Coding
completion
assembly
The siblings had significantly higher reading scores as measured by the WRAT. Differences in spelling and arithmetic approached significance @ = 0.07). Reading scores as measured by the GOR did not differ between the groups @> 0.10). When the achievement scores were corrected for IQ, all group differences disappeared (see Table 2).
257 Pearson correlation coefficients indicated significant correlations between hyperactive children and their siblings for Verbal, Performance, and Full Scale IQ. There were no significant correlations between the hyperactive children and their siblings on any of the achievement tests (see Table 4).
Table 4. Pearson correlation coefficients between hyperactive and nonhyperactive siblings (n = 18 pairs) Variable Verbal
IQ
Performance
P’ 0.007
0.66
0.003
Full Scale IQ
0.69
0.002
WRAT-Reading
0.36
NS
WRAT-Arithmetic
0.17
NS
WRAT-Spelling
0.20
NS
GOR
0.19
NS
1. Two-tailed
IQ
r 0.61
probabilities.
Discussion The data indicate that hyperactive children have significantly lower IQ scores than their nonhyperactive siblings. Analyses of the subtests reveal lower scores for the hyperactive children on almost every subtest; however, only scores on similarities, vocabulary, digit span, and coding differed significantly. These findings, which are contrary to those reported by Stewart et al. (1974), suggest that deficient intellectual capability is not a trait shared by siblings of hyperactive children, but is specific to children suffering from attention deficit disorder with hyperactivity. In fact, the differences found may be spuriously small since the hyperactive subjects were pooled from a sample selected for normal IQ. No such restrictions were used for selecting siblings. The pattern of subtest scores does not clarify the nature of, or the mechanism responsible for, the decreased IQ of the hyperactive children. The poorer performance of the hyperactive children on all subtests is consistent with the notions of minimal brain dysfunction, inattention, or decreased motivation. All of these, not mutually exclusive, factors would be likely to affect multiple aspects of cognitive performance. The achievement test scores indicate that hyperactive children are not behind their siblings in scholastic achievement relative to the expectation for their IQ. These results are similar to those previously reported for hyperactive children and nonsibling controls by Palkes and Stewart (1972) and Welner et al. (1977). Although the mean IQs of hyperactive and nonhyperactive siblings differed significantly, the scores for pairs of siblings were highly correlated with each other. These correlations are similar to those reported for normal siblings (Brody and Brody, 1976). This suggests that familial factors regulating IQ are not qualitatively different in families of hyperactive children as opposed to normals.
258 The data do not support the hypothesis that hyperactive children and their siblings have an inherited intellectual deficit (Stewart et al., 1974). Contrary to that hypothesis, we found no evidence for an intellectual or scholastic deficit in the nonhyperactive siblings. Acknowledgment. The research reported was supported in part by Mental Health Clinical Research Center grant MH-30906 and by U.S. Public Health Service grant MH-18579.
References American
Psychiatric Association.
DSM-III:
Diagnostic
and Statistical
Manual
of Mental
Disorders.
3rd ed. APA, Washington, DC (1980). Brody, E.G., and Brody, N. Intelligence: Nature, Determinants, and Consequences. Academic Press, New York (1976). Cantwell, D.P., and Satterfield, J.H. The prevalence of academic underachievement in hyperactive children. Journal of Pediatric Psychology, 3, 168 (1978). Conners, C.K. A teacher rating scale for use in drug studies with children. American Journal of Psychiatry,
126, 152 (1969).
ECDEU. Assessment Batter.v for Pediatric Psychopharmacology. Department of Health, Education, and Welfare, Washington, DC (1973). Gittelman-Klein, R., Klein, D.F., Katz, S., Saraf, K., and Pollack, E. Comparative effects of methylphenidate and thioridazine in hyperkinetic children. Archives of General Psychiatry,
33, 1217 (1976).
Gray, W.S. Gra_y Oral Reading Test. Bobbs-Merrill, New York (1967). Jastak, J.F., and Jastak, S.R. The Wide Range Achievement Test. Guidance Association of Delaware, Wilmington (1965). Kaufman, A.S. Intelligence Testing With the WISC-R. John Wiley &Sons, New York (1979). Milich, R.S., and Loney, J. The factor composition of the WISC for hyperkinetic/MBD males. Journal of Learning Disabilities, 12, 67 (1979). Minde, K., Lewin, D., Weiss, G., Lavigueur, D.V., and Sykes, E. The hyperactive child in elementary school: A 5 year, controlled, follow-up. Exceptional Child, 38, 215 (1971). Palkes, H., and Stewart, M.A. Intellectual ability and performance of hyperactive children. American
Journal
of Orthopsychiatry,
42, 35 (1972).
Sandberg, S.T., Rutter, M., and Taylor, E. Hyperkinetic disorder in psychiatric clinic attenders. Developmental Medicine and Child Neurology, 20, 279 (1978). Stewart, M.A., Cummings, C., Singer, S., and Deblois, C.S. The overlap between hyperactive and unsocialized aggressive children. Journal of Child Psychology and Psychiatry, 22, 35 (1981).
Stewart, M.A., Palkes, H., Miller, R., Young, C., and Welner, A. intellectual ability and school achievement of hyperactive children, their classmates, and their siblings. In: Ricks, D., Thomas, A., and Roff, M., eds. Life History Research in Psychopathology. Vol. 3. University of Minnesota Press, Minneapolis (1974). Weiner, Z., Welner, R., Stewart, M.A., Palkes, H., and Wish, E. A controlled study of siblings of hyperactive children. Journal of Nervous and Mental Disease, 165, 110 (1977).
Biomedical
253
Press
Do Hyperactive and Academic
Children and Their Siblings Achievement?
Jeffrey
M. Halperin
Received
October 9, 1981; accepted
Differ
in IQ
and Rachel Gittelman December
12. 1981.
Abstract. To test the hypothesis that intellectual deficits are a trait shared by family
members of hyperactive children, 18 hyperactive children were compared to their nonhyperactive siblings on measures of intelligence and academic achievement. As measured by the Wechsler Intelligence Scale for Children, the nonhyperactive siblings had significantly higher Verbal, Performance, and Full Scale IQs. Scores on the Wide Range Achievement Test and the Gray Oral Reading Test did not differ between the groups when adjusted for IQ. Contrary to previous hypotheses, the data suggest that intellectual deficits may be specific to hyperactive children and not a familial trait. Key Words. Hyperactivity, demic achievement.
attention
deficit disorder, siblings, intelligence, aca-
Evidence exists suggesting that the syndrome of hyperactivity, now known as attention deficit disorder with hyperactivity (American Psychiatric Association, 1980) is associated with intellectual and academic achievement deficits. Palkes and Stewart (1972) reported that IQ scores on the Wechsler Intelligence Scale for Children (WISC) were significantly lower in children referred to a clinic and diagnosed as hyperactive than in controls selected from a neighborhood school. Another study (Minde et al., 1971) compared the IQ scores of hyperactive children seen 4 to 6 years earlier at an outpatient clinic to those of their classmates, using the Henman-Nelson Tests of Mental Ability. They also found that the hyperactive children had significantly lower IQ scores. Stewart et al. (1974) investigated differences between nonpatient hyperactive children and their nonhyperactive classmates. Using a teacher rating scale, they screened a large grade school population in a suburban school district for the presence of hyperactive children. They found that scores on the Lorge-Thorndike group intelligence tests for the children rated hyperactive (n = 22) were significantly lower than those of nonhyperactive classmates (n = 296). Despite the use of different subject selection procedures and different measures of intelligence, all three studies resulted in significantly lower IQ scores for hyperactive children as compared to controls. The group differences ranged from 10.5 to 12.4 IQ points. Academic achievement scores, as measured by the Wide Range Achievement Test (WRAT) and the Gray Oral Reading Test (GOR), have also been found to differ significantly between hyperactive children and normal controls. However, when
Jeffrey M. Halperin, Ph.D., and Rachel Gittleman, Ph.D., are at the New York State Psychiatric 722 W 168th St., New York, NY 10032, USA. (Reprint requests to Dr. J.M. Halperin.)
01651781/82/0000-0000/$02.75
@ Elsevier
Biomedical
Press
Institute,
254 achievement test scores were controlled for IQ, group differences disappeared (Palkes and Stewart, 1972). On the other hand, Minde et al. (197 1) matched hyperactive and nonhyperactive children for IQ and found the hyperactives to have significantly poorer school performance. Cantwell and Satterfield (1978) found no significant group differences in WRAT scores between hyperactive children and controls. However, they found that significantly more hyperactive children were underachievers based on the expectation for their age and IQ. The literature strongly suggests that hyperactive children’s intellectual abilities are significantly compromised. This deficit may be a function of their behavioral disorder, which could interfere with test performance, or due to a different, possibly related factor, such as minimal brain dysfunction. In either case, the deficit is specific to the hyperactive child. An alternative hypothesis, proposed by Stewart et al. (1974), posits that the intellectual deficit is not specific to hyperactive children, but rather a trait shared by their family members irrespective of the presence of hyperactivity. This hypothesis is supported by data obtained from a study of nonhyperactive siblings of hyperactive children whose intellectual functioning was compared to that of two groups: (1) their own hyperactive siblings (Stewart et al., 1974) and (2) siblings of a normal control group (Welner et al., 1977). No differences in IQ were found between the hyperactive children and their nonhyperactive siblings. However, the brothers of the hyperactive children were found to have significantly lower scores (6-point difference) than the brothers of controls on the WISC Verbal and Full Scale IQ. No significant IQ score differences occurred between the sisters of hyperactives and controls. Surprisingly, academic achievement scores, when controlled for IQ, were significantly higher in the siblings of the hyperactive children than in the siblings of controls. The interpretation that the above findings indicate intellectual deficits to be a familial trait of hyperactive children is open to question. The hyperactive children in these reports were also reported to have high levels of antisocial behavior, such as stealing (44% of them) and running away. This suggests that many of the patients could have been diagnosed more accurately as having conduct disorders rather than hyperactivity or in conjunction with it. Since children diagnosed as conduct disorders appear to differ from hyperactive children with regard to IQ (Sandberg et al., 1978; Stewart et al., 1981), the study of IQ decrements in hyperactive children requires careful diagnostic definition. To assess whether hyperactive children and their siblings differ in intellectual functioning, WISC IQ scores of objectively defined hyperactive children were compared to those of their nonhyperactive siblings. The hyperactive children did not have concurrent conduct problems as measured by the Conners Teacher Rating Scale (Conners, 1969), and by psychiatric evaluation. In addition, the groups’ WISC subtest scores and their achievement scores on the WRAT (Jastak and Jastak, 1965) and the GOR (Gray, 1967) were compared. Correlations between the scores of hyperactive children and those of their siblings on the WISC, WRAT, and GOR were obtained.
Method Subjects. The subjects in this study were 18 drug-free hyperactive children and 21 of their siblings. The subjects were primarily lower middle class Caucasians from a residential area in
255 New York City. The hyperactive children were a subsample of children who participated in a study previously reported (Gittelman-Klein et al., 1976). The original sample was composed of children who were rated as hyperactive in school according to the Conners Teacher Rating Scale (Conners, 1969), and were also reported to be hyperactive at home or in the clinic. These criteria are described in greater detail in Gittelman-Klein et al. (1976). Other entry criteria to the original study were that the children: (1) be between 6 and 12 years old; (2) be attending school; (3) be free of neurological disease; (4) be nonpsychotic; (5) obtain a Full Scale WISC IQ of at least 80, and either a Verbal or Performance IQ of at least 85; and (6) have no previous history of clinically significant psychopharmacological treatment. The subsample studied in this report were those from a part of the original sample who (1) were found to have no signs indicating the presence of a conduct disorder, as defined by a rating of “yes” or “maybe” on the unsocialized or socialized aggressive items of the Children’s Diagnostic Classification (ECDEU, 1973), and (2) had siblings ranging in age from 6 to 12 years old who were of the same sex as the probands, and were not reported to have any behavior difficulties in school. The hyperactive group comprised 17 boys and 1 girl, and the siblings included 20 boys and 1 girl. The mean ages of the hyperactive group and their siblings were 8 years, 6 months, and 9 years, 3 months, respectively (p > 0.10). Procedures. All children were administered the WISC, WRAT, and GOR. The two groups were compared, using two-tailed I tests, to see if they differed in IQ, WISC subtest scores, and achievement scores. The achievement score differences were contrasted further, controlling for
IQ. Pearson correlation coefficients were determined between the scores of the hyperactive children and their nonhyperactive siblings on the WISC, WRAT, and GOR. To pair the groups for the correlation, the sibling closest in age to the hyperactive child was used in cases in which there was more than one sibling.
Results Table 1 shows the factor scores for the 18 hyperactive children on the Conners Teacher Rating Scale. Scores on the conduct problem factor are significantly @ < 0.00 1) lower than those for the inattention and hyperactivity factors.
Table 1. Factor scores for hyperactive Conners Teacher Rating Scale1 Factor 1. Conduct
problems
children
Mean
SD
on the
1.02
0.56
Il. Inattention
1.76
0.47
Ill. Anxiety
0.55
0.56
IV. Hyperactivity
2.23
0.45
-1.26
0.78
V. Health 1, Scale range from 0 to 3
As shown in Table 2, both groups had WISC IQ scores within normal limits. The siblings, however, had significantly higher Verbal, Performance, and Full Scale IQ scores. Analyses examining differences between the two groups on the individual subtests revealed that similarities, vocabulary, digit span, and coding differed significantly (see Table 3).
256
Table 2. IQ and achievement hyperactive siblings
scores for hyperactive
children
and their non-
Group Hyperactive (n = 18) Measures Verbal
IQ
Performance
IQ
Siblings (n = 21)
Mean
SD
Mean
SD
t
P
99.0
12.2
111.7
12.7
3.78
0.003
98.8
12.5
108.3
11.4
2.48
0.02
Full Scale IQ
98.9
11.1
111.1
10.6
3.50
0.001
WRAT-Reading1
93.4
11.8
108.4
17.9
3.05
0.0042
WRAT-Spelling1
91.9
9.4
101.3
19.2
1.89
0.072
WRAT-Arithmetic1
93.2
9.5
99.0
9.7
1.86
0.072
GORs
-1.4
1.2
-0.5
2.3
1.41
NS2
1. Standard scores. 2. Not significant when corrected for IQ.
3. Difference between grade score and expected grade for age
Table 3. WISC subtest scaled scores for hyperactive nonhvoeractive siblinas
children
and their
GrOUD
Hyperactive Subtest Information Comprehension Arithmetic
(n = 18)
Siblings (n = 21)
Mean
SD
Mean
SD
t
9.33
2.11
11.10
3.22
1.98
0.06
10.44
2.90
10.95
2.16
0.65
NS
P
9.83
3.00
11.10
2.19
1.52
NS
Similarities
11.11
3.50
13.24
2.66
2.15
0.04
Vocabulary
9.78
2.80
12.33
2.11
3.25
0.002
Digit span
9.28
2.27
11.67
2.83
2.87
0.007
Picture
9.78
2.46
10.48
3.44
0.72
NS
Picture arrangement
10.89
2.87
12.38
2.56
1.72
0.09
Block design
10.33
2.38
10.71
2.65
0.47
NS
Object
10.22
3.44
11.71
2.51
1.56
NS
7.94
2.18
10.62
2.60
3.45
0.001
Coding
completion
assembly
The siblings had significantly higher reading scores as measured by the WRAT. Differences in spelling and arithmetic approached significance @ = 0.07). Reading scores as measured by the GOR did not differ between the groups @> 0.10). When the achievement scores were corrected for IQ, all group differences disappeared (see Table 2).
257 Pearson correlation coefficients indicated significant correlations between hyperactive children and their siblings for Verbal, Performance, and Full Scale IQ. There were no significant correlations between the hyperactive children and their siblings on any of the achievement tests (see Table 4).
Table 4. Pearson correlation coefficients between hyperactive and nonhyperactive siblings (n = 18 pairs) Variable Verbal
IQ
Performance
P’ 0.007
0.66
0.003
Full Scale IQ
0.69
0.002
WRAT-Reading
0.36
NS
WRAT-Arithmetic
0.17
NS
WRAT-Spelling
0.20
NS
GOR
0.19
NS
1. Two-tailed
IQ
r 0.61
probabilities.
Discussion The data indicate that hyperactive children have significantly lower IQ scores than their nonhyperactive siblings. Analyses of the subtests reveal lower scores for the hyperactive children on almost every subtest; however, only scores on similarities, vocabulary, digit span, and coding differed significantly. These findings, which are contrary to those reported by Stewart et al. (1974), suggest that deficient intellectual capability is not a trait shared by siblings of hyperactive children, but is specific to children suffering from attention deficit disorder with hyperactivity. In fact, the differences found may be spuriously small since the hyperactive subjects were pooled from a sample selected for normal IQ. No such restrictions were used for selecting siblings. The pattern of subtest scores does not clarify the nature of, or the mechanism responsible for, the decreased IQ of the hyperactive children. The poorer performance of the hyperactive children on all subtests is consistent with the notions of minimal brain dysfunction, inattention, or decreased motivation. All of these, not mutually exclusive, factors would be likely to affect multiple aspects of cognitive performance. The achievement test scores indicate that hyperactive children are not behind their siblings in scholastic achievement relative to the expectation for their IQ. These results are similar to those previously reported for hyperactive children and nonsibling controls by Palkes and Stewart (1972) and Welner et al. (1977). Although the mean IQs of hyperactive and nonhyperactive siblings differed significantly, the scores for pairs of siblings were highly correlated with each other. These correlations are similar to those reported for normal siblings (Brody and Brody, 1976). This suggests that familial factors regulating IQ are not qualitatively different in families of hyperactive children as opposed to normals.
258 The data do not support the hypothesis that hyperactive children and their siblings have an inherited intellectual deficit (Stewart et al., 1974). Contrary to that hypothesis, we found no evidence for an intellectual or scholastic deficit in the nonhyperactive siblings. Acknowledgment. The research reported was supported in part by Mental Health Clinical Research Center grant MH-30906 and by U.S. Public Health Service grant MH-18579.
References American
Psychiatric Association.
DSM-III:
Diagnostic
and Statistical
Manual
of Mental
Disorders.
3rd ed. APA, Washington, DC (1980). Brody, E.G., and Brody, N. Intelligence: Nature, Determinants, and Consequences. Academic Press, New York (1976). Cantwell, D.P., and Satterfield, J.H. The prevalence of academic underachievement in hyperactive children. Journal of Pediatric Psychology, 3, 168 (1978). Conners, C.K. A teacher rating scale for use in drug studies with children. American Journal of Psychiatry,
126, 152 (1969).
ECDEU. Assessment Batter.v for Pediatric Psychopharmacology. Department of Health, Education, and Welfare, Washington, DC (1973). Gittelman-Klein, R., Klein, D.F., Katz, S., Saraf, K., and Pollack, E. Comparative effects of methylphenidate and thioridazine in hyperkinetic children. Archives of General Psychiatry,
33, 1217 (1976).
Gray, W.S. Gra_y Oral Reading Test. Bobbs-Merrill, New York (1967). Jastak, J.F., and Jastak, S.R. The Wide Range Achievement Test. Guidance Association of Delaware, Wilmington (1965). Kaufman, A.S. Intelligence Testing With the WISC-R. John Wiley &Sons, New York (1979). Milich, R.S., and Loney, J. The factor composition of the WISC for hyperkinetic/MBD males. Journal of Learning Disabilities, 12, 67 (1979). Minde, K., Lewin, D., Weiss, G., Lavigueur, D.V., and Sykes, E. The hyperactive child in elementary school: A 5 year, controlled, follow-up. Exceptional Child, 38, 215 (1971). Palkes, H., and Stewart, M.A. Intellectual ability and performance of hyperactive children. American
Journal
of Orthopsychiatry,
42, 35 (1972).
Sandberg, S.T., Rutter, M., and Taylor, E. Hyperkinetic disorder in psychiatric clinic attenders. Developmental Medicine and Child Neurology, 20, 279 (1978). Stewart, M.A., Cummings, C., Singer, S., and Deblois, C.S. The overlap between hyperactive and unsocialized aggressive children. Journal of Child Psychology and Psychiatry, 22, 35 (1981).
Stewart, M.A., Palkes, H., Miller, R., Young, C., and Welner, A. intellectual ability and school achievement of hyperactive children, their classmates, and their siblings. In: Ricks, D., Thomas, A., and Roff, M., eds. Life History Research in Psychopathology. Vol. 3. University of Minnesota Press, Minneapolis (1974). Weiner, Z., Welner, R., Stewart, M.A., Palkes, H., and Wish, E. A controlled study of siblings of hyperactive children. Journal of Nervous and Mental Disease, 165, 110 (1977).