5
Performance of Retarded Children, With and Without Down Syndrome, on the Bruininks Oseretsky Test of Motor Proficiency BARBARA H. CONNOLLY and BETH T. MICHAEL The purpose of this study was to examine the gross motor and fine motor abilities of children with mental retardation using the Bruininks Oseretsky Test of Motor Proficiency. We compared the motor skills of 24 mentally retarded children, 12 with Down syndrome and 12 without Down syndrome. The children ranged in chronological age from 7.6 years to 11 years and were of comparable mental age. Within each group, there were no significant sex differences nor were there differences between the two groups in motor performance for the male subjects. The female subjects with Down syndrome, however, scored significantly lower than female subjects without Down syndrome on running speed, strength, visual motor ability, speed, and dexterity and fine motor composite scores. As a group, the children with Down syndrome scored significantly lower than the children without Down syndrome in the areas of running speed, balance, strength, and visual motor control. The gross motor and fine motor skill composite scores were also significantly lower for the children with Down syndrome than for the children without Down syndrome. Key Words: Child development, Downs syndrome, Mental retardation, Motor skills. Physical therapists have long been in- terested in the assessment of fine motor and gross motor skills of the mentally retarded child. From infancy, the child with mental retardation may have mo- tor development that progresses at a slower rate than that expected for a child with average intelligence. Parents who are sensitive to the development of their child may detect the delay in motor skill acquisition before becoming aware of the cognitive delays. According to Malpass, the sequence of motor development in children who are classified as trainably mentally re- tarded (TMR) approximates that of chil- dren of average intelligence whose gross motor skills continue to develop until they are 16 years of age. 1 The TMR child, however, shows a delay in the rate of acquisition of those skills. The degree of the delay depends on the type of skill. The child usually has difficulty with co- ordination and exhibits less manipula- tive dexterity than children of average intelligence of the same age and sex. 1 Most TMR children show some form of central nervous system dysfunction that leads one to expect problems involving coordination, gait, and fine motor abil- ities. 2 In general, studies indicate that the mean scores of motor skill profi- ciency of mentally retarded children are inferior to the mean scores of children with average intelligence quotients (IQs). 3,4 Groden reported substantial relation- ships between IQs and motor skill pro- ficiency. 5 Even when the influence of purely motor disabilities (eg, finger tap- ping and grip tests) was controlled, a perceptual motor task in which the sub- jects quickly and consecutively pressed four buttons arranged in a square showed a significant relationship be- tween motor skill proficiency and IQ. 5 Trainably mentally retarded children without any specific motor skill disabil- ities, therefore, may show deficiencies in performing complex motor skill tasks. Groden's research also indicated that mentally retarded children not only have much less strength than children with average IQs but become fatigued more quickly. 5 Hayden also found that mentally retarded children are only half as strong physically as their nonretarded peers. 6 In contrast, another study re- vealed that children who were moder- ately retarded performed as well as their nonretarded peers on a strength and grip test. 7 These same moderately retarded children, however, performed much more poorly than their nonretarded peers on tests of hand steadiness, eye- hand coordination, dexterity, and re- sponsiveness. Slow reaction times to test items have been reported by various researchers. 7,8 Within the population of mentally re- tarded children, the gross motor skills of the child with Down syndrome have been studied closely. The rate of motor development of children with Down syndrome is slightly below that of non- Down syndrome children. 9-11 During the first 6 months of life, the motor skill development of infants with Down syn- drome closely parallels that of non- Down syndrome infants, although in- fants with Down syndrome develop at a slightly slower rate. By the age of 12 months, however, the motor skill devel- opment of the child with Down syn- drome often is 4 to 5 months behind Dr. Connolly is Associate Professor, Department of Rehabilitation Sciences, Program in Physical Therapy, The University of Tennessee Center for the Health Sciences, 800 Madison Ave, Memphis, TN 38163 (USA). Ms. Michael is Instructor, Department of Reha- bilitation Sciences, Program in Physical Therapy, The University of Tennessee Center for the Health Sciences and Acting Chief, Child Development Center, The University of Tennessee Center for the Health Sciences. This study was supported in part by US Public Health Service Grants MCT-002041-01 and MCT- 900. This article was submitted March 12, 1985; was with the authors for revision eight weeks; and was accepted August 6, 1985. 344 PHYSICAL THERAPY

Performance of Retarded Children, With and Without … of Retarded Children, With and Without Down Syndrome, on the Bruininks Oseretsky Test of Motor Proficiency BARBARA H. CONNOLLY

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Performance of Retarded Children, With and Without Down Syndrome, on the Bruininks Oseretsky Test of Motor Proficiency

BARBARA H. CONNOLLY and BETH T. MICHAEL

The purpose of this study was to examine the gross motor and fine motor abilities of children with mental retardation using the Bruininks Oseretsky Test of Motor Proficiency. We compared the motor skills of 24 mentally retarded children, 12 with Down syndrome and 12 without Down syndrome. The children ranged in chronological age from 7.6 years to 11 years and were of comparable mental age. Within each group, there were no significant sex differences nor were there differences between the two groups in motor performance for the male subjects. The female subjects with Down syndrome, however, scored significantly lower than female subjects without Down syndrome on running speed, strength, visual motor ability, speed, and dexterity and fine motor composite scores. As a group, the children with Down syndrome scored significantly lower than the children without Down syndrome in the areas of running speed, balance, strength, and visual motor control. The gross motor and fine motor skill composite scores were also significantly lower for the children with Down syndrome than for the children without Down syndrome.

Key Words: Child development, Downs syndrome, Mental retardation, Motor skills.

Physical therapists have long been in­terested in the assessment of fine motor and gross motor skills of the mentally retarded child. From infancy, the child with mental retardation may have mo­tor development that progresses at a slower rate than that expected for a child with average intelligence. Parents who are sensitive to the development of their child may detect the delay in motor skill acquisition before becoming aware of the cognitive delays.

According to Malpass, the sequence of motor development in children who are classified as trainably mentally re­tarded (TMR) approximates that of chil­dren of average intelligence whose gross motor skills continue to develop until they are 16 years of age.1 The TMR

child, however, shows a delay in the rate of acquisition of those skills. The degree of the delay depends on the type of skill. The child usually has difficulty with co­ordination and exhibits less manipula­tive dexterity than children of average intelligence of the same age and sex.1

Most TMR children show some form of central nervous system dysfunction that leads one to expect problems involving coordination, gait, and fine motor abil­ities.2 In general, studies indicate that the mean scores of motor skill profi­ciency of mentally retarded children are inferior to the mean scores of children with average intelligence quotients (IQs).3,4

Groden reported substantial relation­ships between IQs and motor skill pro­ficiency.5 Even when the influence of purely motor disabilities (eg, finger tap­ping and grip tests) was controlled, a perceptual motor task in which the sub­jects quickly and consecutively pressed four buttons arranged in a square showed a significant relationship be­tween motor skill proficiency and IQ.5

Trainably mentally retarded children without any specific motor skill disabil­ities, therefore, may show deficiencies in performing complex motor skill tasks. Groden's research also indicated that mentally retarded children not only

have much less strength than children with average IQs but become fatigued more quickly.5 Hayden also found that mentally retarded children are only half as strong physically as their nonretarded peers.6 In contrast, another study re­vealed that children who were moder­ately retarded performed as well as their nonretarded peers on a strength and grip test.7 These same moderately retarded children, however, performed much more poorly than their nonretarded peers on tests of hand steadiness, eye-hand coordination, dexterity, and re­sponsiveness. Slow reaction times to test items have been reported by various researchers.7,8

Within the population of mentally re­tarded children, the gross motor skills of the child with Down syndrome have been studied closely. The rate of motor development of children with Down syndrome is slightly below that of non-Down syndrome children.9-11 During the first 6 months of life, the motor skill development of infants with Down syn­drome closely parallels that of non-Down syndrome infants, although in­fants with Down syndrome develop at a slightly slower rate. By the age of 12 months, however, the motor skill devel­opment of the child with Down syn­drome often is 4 to 5 months behind

Dr. Connolly is Associate Professor, Department of Rehabilitation Sciences, Program in Physical Therapy, The University of Tennessee Center for the Health Sciences, 800 Madison Ave, Memphis, TN 38163 (USA).

Ms. Michael is Instructor, Department of Reha­bilitation Sciences, Program in Physical Therapy, The University of Tennessee Center for the Health Sciences and Acting Chief, Child Development Center, The University of Tennessee Center for the Health Sciences.

This study was supported in part by US Public Health Service Grants MCT-002041-01 and MCT-900.

This article was submitted March 12, 1985; was with the authors for revision eight weeks; and was accepted August 6, 1985.

344 PHYSICAL THERAPY

RESEARCH

that of the 1-year-old child without Down syndrome. At the age of 5 years, the motor skill development of the child with Down syndrome is approximately two years behind that of the child with­out Down syndrome, and he performs many activities at 50% to 70% below the normal rate.12,13 Share reported that none of the 212 children with Down syndrome under 7 years of age in his study could perform such motor tasks as buttoning a shirt or riding a tricycle.14

Interestingly, it has been suggested that female performance is superior to that of male performance on motor skill tasks.15,16

Several studies have demonstrated that children with Down syndrome gen­erally have deficits in eye-hand coordi­nation, laterality, and visual motor con­trol.17-22 Reaction times also have been shown to be slower in children with Down syndrome when compared with reaction times of other children with mental retardation.23,24 Poor balance also has been cited as a deficit.25 Poor muscle tone, awkwardness of move­ment, flabby hands, and short fingers have been reported as causes of these delayed skills.26

In a recent study by Connolly et al, the gross motor and fine motor skills of a group of children with Down syn­drome were evaluated using the Bruin-inks Oseretsky Test of Motor Profi­ciency.27 That study showed that fine motor skills requiring eye-hand coordi­nation, laterality, and visual motor con­trol were among the most advanced in these children. In ranked scores on the Bruininks Oseretsky subtests, the high­est scores were obtained on upper limb coordination. The children encountered some difficulties in the subtests requir­ing balance. Hypotonia and the effects of hypotonia, such as decreased pelvic stability and pes planus, were thought to contribute to balance problems seen in activities involving one-foot standing, tandem walking, and running.

The only gross motor skill subtest cat­egory that ranked in the top scores was strength. Connolly et al postulated that these items—push-ups, sit-ups, and broad jumps—all were components of physical education programs and that the scores on the strength test might reflect practice effects.27

Although there is general agreement that children with Down syndrome per­form below average in fine motor and gross motor skills, the discrepancy be-

TABLE1 Representation of Subject Classification by Age, Sex, and Intelligence Quotient

Subjects

Mean chronological age (yr) Chronological age range (yr) Mean IQ IQ range Boys Girls

Down Syndrome

9.16a

7.6-10.5 54.5b

38-69 3 9

Non-Down Syndrome

9.25a

7.9-11.0 56.8b

42-66 7 5

tween the motor skills of the child with Down syndrome and those of the men­tally retarded child without Down syn­drome has been disputed.28 Some inves­tigations between matched groups of mentally retarded children, one group with and one group without Down syn­drome, found no significant differences between the motor skills of children with Down syndrome and those of chil­dren without Down syndrome.7,25, 29 The children with Down syndrome actually performed some motor skill tasks supe­riorly.25 Henderson et al, however, found that children with Down syn­drome performed tasks more slowly and had more difficulty with balance tests than did children who were mentally retarded but without Down syndrome.21

Sixty-four percent of the mentally re­tarded children without Down syn­drome, for example, could maintain their balance on one foot for longer than four seconds, but only 35% of the chil­dren with Down syndrome could do the task.21 Other studies suggest that if the children with Down syndrome under­stand the task and are of comparable mental age, they have motor skills equal to mentally retarded children without Down syndrome.7,30,31

The purpose of this study was to ex­amine the gross motor and fine motor abilities of children with mental retar­dation using the Bruininks Oseretsky Test of Motor Proficiency. We com­pared the motor skills of mentally re­tarded children with Down syndrome with those of mentally retarded children without Down syndrome and addressed the following questions:

1. Do significant differences exist be­tween the gross motor skills of mentally retarded children with Down syndrome and those of mentally retarded children without Down syndrome as tested by the Bruininks Oseretsky Test of Motor Proficiency?

2. Do significant differences exist be­tween the fine motor skills of men­tally retarded children with Down syndrome and those of mentally retarded children without Down syndrome as tested by the Bruin­inks Oseretsky Test of Motor Pro­ficiency?

3. Do significant differences exist be­tween the gross motor and fine motor skill levels of male subjects and those of female subjects as tested by the Bruininks Oseretsky Test of Motor Proficiency?

METHOD

Subjects We performed motor proficiency test­

ing on 24 children who had been tested previously using the Stanford-Binet In­telligence Scale and who had been di­agnosed by a psychologist as being men­tally retarded. Twelve of the children had been diagnosed as having Down syndrome. The other 12 children were diagnosed as being mentally retarded but without any type of neuromotor dysfunction or genetic defect. None of the children were enrolled in physical therapy programs at the time of the study.

The children with Down syndrome ranged in age from 7 years 7 months to 10 years 6 months ( = 9 years 2 months, s = 13.1 months). The children without Down syndrome ranged in age from 7 years 11 months to 11 years ( = 9 years 3 months, s = 10.2 months). The children with Down syndrome had IQs ranging from 38 to 69 ( = 54,5, s = 9.64). The children without Down syndrome had IQs ranging from 42 to 66 ( = 56.8, s = 9.06). The t-test analyses of both chronological age and IQs yielded no significant differences be­tween the two groups. Table 1 describes the children involved in the study by age, IQ, and sex.

a Not significant at t = .313, df = 22. b Not significant at t = .610, df = 22.

Volume 66 / Number 3, March 1986 345

TABLE 2 Summary of Median Developmental Ages and Range of Developmental Ages for Gross Motor and Fine Motor Skills

Skillsa

Running speedb

median range

Balancec

median range

Bilateral coordination median range

Strengthc

median range

Gross motor skill compositec

median range

Upper limb coordination median range

Response time median range

Visual motor skill controlc

median range

Upper limb speed and dexterity median range

Fine motor skill composite0

median range

Down Syndrome (yr-mo)

4-2 below 4-2 to 5-5

4-3.5 below 4-2 to 5-5

5-2 below 4-2 to 7-11

5-11 4-2 to 8-2

4-8.8 below 4-2 to 6-0

5-11 4-2 to 9-2

below 4-2 below 4-2 to 6-11

4-5 below 4-2 to 7-11

5-5 4-2 to 6-5

4-3.5 below 4-2 to 6-2

(n)

(12)

(12)

(12)

(12)

(12)

(12)

(8)

(12)

(12)

(12)

Non-Down Syndrome (yr-mo)

6-0.5 4-2 to 8-11

5-2 below 4-2 to 10-2

6-5 below 4-2 to 7-11

7-3.5 4-11 to 10-8

6-6.3 below 4-2 to 8-5

5-7.5 below 4-2 to 8-5

5-3.5 below 4-2 to 7-11

6-0 below 4-2 to 10-2

5-9.5 4-2 to 7-5

6-0 below 4-2 to 7-2

(n)

(12)

(12)

(12)

(12)

(12)

(12)

(12)

(12)

(12)

(12)

All of the children attended special education classes in a large metropolitan city in the South. A signed informed consent was obtained from the parents of each child before testing of the child was performed.

Tests

The Bruininks Oseretsky Test of Mo­tor Proficiency (long form) was admin­istered to each of the children. The Bruininks Oseretsky test includes sub­tests in running speed, balance, bilateral coordination of the arms and legs, strength, upper limb coordination, re­sponse time, visual motor control, and speed and dexterity of the upper extrem­ities. The Bruininks Oseretsky Test of Motor Proficiency, a standardized test, yields age levels for each of the individ­ual subtests, a gross motor skills com­posite age, and a fine motor skills com­posite age. The test is standardized for

children between the ages of 4 years, 2 months and 16 years. If a child scores below the basal age of the test, 4 years, 2 months, he is assigned a score of below 4 years, 2 months.

Procedures

Each child was assessed individually by one of us. The order of the testing of the children was random and not ac­cording to developmental or chronolog­ical age. A total of 1.5 to 2 hours was spent with each child in obtaining the data. Standardized procedures were used according to the test manual for the Bruininks Oseretsky Test of Motor Proficiency. Interrater reliability for ad­ministration of the test in accordance with the standardized procedures has been reported as between .90 and .98 even when the rater has had no formal training in the scoring.32

Data Analysis

Descriptive statistics were used to de­scribe the characteristics of the children involved in the study. Statistical analysis of the data on age and intellectual func­tioning of the children included the t test for differences between the means of two groups. Statistical analysis of the data obtained with the Bruininks Oser­etsky Test of Motor Proficiency was per­formed using the Mann-Whitney U rank sum test because the scores had to be ranked as a result of noninterval data (eg, below 4 years, 2 months). The level of significance used throughout the study was p = .05; however, if a level of significance was found to be greater than .05, that level was reported in the find­ing.

RESULTS

The results of the Bruininks Oseretsky Test of Motor Proficiency revealed vary­ing degrees of differences on the individ­ual subtests. The median scores for each subtest for the two groups and the range of scores are shown in Table 2. Analysis of the individual subtests between the two groups using the Mann-Whitney U test yielded significant differences be­tween the two groups in the areas of running speed, balance, strength, and visual motor control with the children without Down syndrome scoring signif­icantly higher than the children with Down syndrome. The two groups also had significantly different gross motor and fine motor skill composite scores, again with the children without Down syndrome scoring significantly higher than the children with Down syndrome.

When we compared the scores on the individual subtests within groups by sex, we found that the scores of the boys and girls with Down syndrome were not sig­nificantly different. We also found that the scores of the boys and girls without Down syndrome were not significantly different.

The scores of the girls with Down syndrome (n = 9) were significantly higher than the scores of the girls with­out Down syndrome (n = 5), however, in the areas of running speed, strength, visual motor control, and upper limb speed and dexterity and in their fine motor skill composite scores. We noted no significant differences between the scores of the boys with Down syndrome (n = 3) and the scores of the boys with-

a Bruininks Oseretsky Test of Motor Proficiency. bp<.005. cp<.05.

346 PHYSICAL THERAPY

RESEARCH

out Down syndrome (n = 7) on any of the subtests or motor skill composites.

As a part of the Bruininks Oseretsky test, we determined arm preference. In our sample, 10 children were right-handed, 8 were left-handed, and 6 were ambidextrous. Our sample represents a greater number of left-handed children than we would expect to find in a com­parable sample of nonretarded children. Fagan-Dubin, in a study of 1,257 non-retarded children, found 11.4% to be left-handed, as compared with the 33.3% found in our study.33 We found no significant difference in handedness between the children with Down syn­drome and those without Down syn­drome when a chi-square analysis was performed.

DISCUSSION

The results of our study indicate that significant differences in gross motor skills and fine motor skills exist between mentally retarded children with Down syndrome and mentally retarded chil­dren without Down syndrome. As indi­cated by the results of the Bruininks Oseretsky subtests, differences were noted in the areas of running speed, balance, strength, visual motor skill con­trol, and overall gross motor and fine motor skill performance. In our study, the group of children with Down syn­drome and the group of children with­out Down syndrome were of compara­ble mental age. The results of our study, therefore, do not support the results of earlier studies reporting that children with Down syndrome have skills com­parable to those of retarded children of the same mental age without Down syn-drome.7,25,29-31 Henderson et al21 and Nakamura25 have reported that children with Down syndrome have more diffi­culty with 'balance tasks than children with mental retardation but without Down syndrome. Their findings are sup­ported by the findings of our study be­cause we found balance to be signifi­cantly different between the two groups. The neuropathology associated with Down syndrome includes delayed cere­bellar maturation and a relatively small cerebellum and brain stem.34 Thus, the clinical finding of balance and coordi­nation problems in the child with Down syndrome may be related to neuropath­o l o g y causes.

We did not detect the slower reaction times others found in their studies of children with Down syndrome.23,24 Al­

though we did not find any significant difference between the two groups on the response speed subtest, only 8 of the 12 children with Down syndrome were able to perform this particular subtest.

Strength has been reported as being an area of deficit in all children with mental retardation.6 We noted a signif­icant difference between the children with Down syndrome and those without Down syndrome. Both groups, however, performed at greater than one-half the strength of their nonretarded peers, in contrast to the findings of Hayden.6

We found significant differences be­tween the two groups in the area of visual motor skill control and in overall fine motor skill performance with the children without Down syndrome scor­ing higher. These results support pre­vious studies that reported deficits in eye-hand coordination and visual motor skill control for children with Down syn­drome.17"22 The children with Down syndrome, however, did not differ sig­nificantly on the subtest of upper limb speed and dexterity, in contrast to the findings reported by Knights et al.7

Although we used small numbers of children in the analysis of sex differ­ences, the results revealed no significant differences between the performances of boys and girls with Down syndrome, nor between the performances of boys and girls without Down syndrome. Studies that had reported the superiority of girls with Down syndrome over boys with Down syndrome in the performance of motor skill tasks are not supported by our findings.1516 In fact, when we com­pared girls with Down syndrome with girls without Down syndrome, we noted significantly poorer performance in the areas of running speed, balance, strength, visual motor skill control, and upper limb speed and dexterity and in fine motor skill composite scores for the girls with Down syndrome. When we compared boys with Down syndrome to boys without Down syndrome, how­ever, we found no significant differ­ences. Thus, the lower scores of the girls with Down syndrome appear to provide the basis for the differences between the two groups as a whole.

In both groups of children in this study, we noted a higher incidence of left-handedness than we would expect in a sample of nonretarded children. Other researchers have reported that children with mental retardation have a

higher incidence of left-handedness, and this was the finding of our studv.35-37

Although we do not attempt to delin­eate the causes of the differences be­tween the two groups in our study, the findings are of clinical relevance to phys­ical therapists. The areas in which the children with Down syndrome per­formed poorly—running speed, bal­ance, strength, and visual motor skill control—suggest that the child with Down syndrome may continue to have neurological problems far beyond the preschool period and into adolescence. Currently, the majority of physical ther­apy available to the child with Down syndrome is provided during the pre­school years and not after the child en­ters a regular school program. If the child with Down syndrome does receive structured physical education program­ming, the activities are of a general na­ture, and the child is treated in a group setting instead of receiving individual­ized programming. Our study has shown that differences in the gross mo­tor and fine motor skills exist between the mentally retarded child with Down syndrome and the mentally retarded child without Down syndrome. There­fore, the child with Down syndrome may continue to need individualized physical therapy as a part of his special education programming to address his particular motor skill needs. The neu­ropathology associated with Down syn­drome, particularly as related to the small size of the cerebellum and the brain stem, suggests that children with Down syndrome may experience prob­lems with balance and coordination. This finding strongly supports our sup­position that individualized physical therapy may be appropriate for children with Down syndrome not only during their preschool years but throughout their adolescence.

CONCLUSION

The results of our study indicate that children with Down syndrome perform poorly in the areas of running speed, balance, strength, and visual motor skill control and in overall gross motor and fine motor skills in comparison with mentally retarded children without Down syndrome but of comparable chronological and mental ages. Al­though our study addressed specific questions regarding motor functioning in children with Down syndrome in

Volume 66 / Number 3, March 1986 347

comparison with mentally retarded chil­dren without Down syndrome, more re­search is needed on a larger sample of children. We found significant differ­ences between the girls with Down syn­drome and those without Down syn­drome; the non-Down syndrome girls scored higher. We were unable to detect any significant differences, however, be­tween boys with Down syndrome and those without Down syndrome. The number of children in this analysis was small and a larger sample size should be used in any future research in this area.

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348 PHYSICAL THERAPY