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International Journal of Developmental Disabilities logoLink to International Journal of Developmental Disabilities
. 2021 Jul 19;69(2):238–247. doi: 10.1080/20473869.2021.1948318

Exploring the effect of motor coordination on repetitive behaviours in children with autism spectrum disorder

Cebrail Karadaş 1,✉, Hatice Bakkaloğlu 1, Şeyda Demir 1
PMCID: PMC10071942  PMID: 37025329

Abstract

Objective: This study was conducted to explore the effect of motor coordination on repetitive behaviors in children with Autism Spectrum Disorder (ASD) aged 5–15 years.

Methods: The study employed the causal-comparative design, one of the correlational survey designs. The study was carried out with data obtained from parents of 241 children with ASD. The parents were administered the measurement tools of Gilliam Autism Rating Scale-2-Turkish Version to confirm the diagnosis of ASD, Demographic Information Form to obtain information about the child and the parent, Repetitive Behavior Scale-Revised-Turkish Version to evaluate the repetitive behaviors, and Developmental Coordination Disorder Questionnaire-07-Turkish Version to evaluate the motor coordination performance. The data were analyzed MANCOVA in the R package program.

Results: The study results revealed that 72% of children with ASD had a risk of Developmental Coordination Disorder (DCD). The repetitive behaviors of children with and without DCD risk differed significantly. The severity and intensity of the repetitive behaviors of children with DCD risk were higher than those without DCD risk when age, gender, and comorbidity were taken under control.

Conclusion: The motor coordination problems in children with ASD are effective on repetitive behaviors.

Keywords: Autism spectrum disorder, repetitive behaviors, stereotypic behaviors, motor coordination, motor performance, motor coordination disorder

Introduction

Autism spectrum disorder (ASD), whose incidence and prevalence has increased considerably since the disorder was first defined by Leo Kanner (1943) until today (Baio 2014, Baio et al. 2018, Maenner et al. 2020, Wing 1993), is seen in approximately 2% of the population today (Maenner et al. 2020). Over the years, not only the incidence and prevalence of ASD changed but also different applications emerged in diagnostic criteria, definition, and classification of ASD (American Psychiatric Association 2000, 2013). Based on the current practice, the two basic diagnostic criteria of ASD are social interaction and communication deficits, and the other is restricted and repetitive behaviors. While difficulties in social interaction manifest themselves with very limited use of imitation skills, eye contact, gestures, and facial expressions (Carter et al. 1996), difficulties in communication manifest themselves with a language disorder, inability to use language at all, or deficits in initiating and maintaining communication (Baker et al. 2010). The other basic diagnostic criteria, restricted and repetitive behaviors, is an umbrella concept including the repetitive manipulation of objects, stereotypical motor movements, self-harming behavior, rituals and routines, insistence on sameness, and restricted interests. Excessive preoccupation with the manipulation of certain objects or parts of an object, unusual attachment to an object or repeated manipulation of parts of the object, opening and closing doors repeatedly or constantly looking at rotating objects, shaking the whole or part of the body to the right or the left or back and forth, and repeated shaking of hands or arms may be given as examples to these behaviors (APA 2013, Cunningham and Schreibman 2008, Lewis and Bodfish 1998).

Repetitive behaviors may also be seen in different dimensions among children with ASD, and the individual may exhibit a wide variety of behavioral patterns over time (Bishop et al. 2013). These behaviors negatively affect children with ASD in many aspects. Although repetitive behaviors occur less in educational sessions compared to free time (Sayers et al. 2011), learning processes are negatively affected by these behaviors. For example, a child who exhibits these behaviors may have a very limited time to participate in the activity or the child may not participate in the activity at all, which negatively affects the learning process or daily life. In addition, since repetitive behaviors appear from the early stages of life, they also restrict the progress in developmental areas (Matson et al. 2010, Sayers et al. 2011).

It is critical to reveal the effective variables on repetitive behaviors affecting development and learning (Lewis and Kim 2009), socialization, full participation in inclusive settings (Conroy et al. 2005), and the quality of life of the child and family in general (Healy and Leader 2011). Previous studies suggested several arguments in explaining these behaviors (Joseph 1999, Kennedy et al. 2000, Lopez et al. 2005, Sayers et al. 2011). The first of these argued that children cannot exhibit desired behaviors due to their developmental disabilities (Lopez et al. 2005, Sayers et al. 2011). The second argued that the repetitive behaviors cannot be controlled due to the restriction in executive function skills of children with ASD and thus the frequency and intensity increase (Joseph 1999, Sayers et al. 2011). The third argued that children with ASD exhibit repetitive behaviors in order to get sensory stimuli (Kennedy et al. 2000). After the repetitive behaviors that appear with the purpose stated in this argument, the individual usually reinforces himself or herself automatically in a sensory sense. Therefore, it might be very difficult to get positive results from the interventions made for these behaviors (Piazza et al. 2000).

In the literature, there are studies examining factors such as age, comorbidity, and gender associated with the intensity and severity of repetitive behaviors. Several studies revealed that the intensity and variety of repetitive behaviors differ according to age (Bishop et al. 2013, Esbensen et al. 2009, Militerni et al. 2002, Richler et al. 2010). Among these studies, there are some researchers (Bishop et al. 2013, Esbensen et al. 2009) suggesting that some of the repetitive behaviors (ritualistic, stereotypical) decrease as age increases (Bishop et al. 2013, Esbensen et al. 2009), whereas some studies are suggesting that some of the repetitive behaviors (insistence on sameness) increase as age increases. These studies argued that the individual exhibits different behavioral patterns over time. In addition, the intensity and severity of repetitive behaviors differ when comorbid disorders exist ASD (Bishop et al. 2006, Bourreau et al. 2009, Lam et al. 2008). When evaluating this difference, it is possible to say that those with comorbidity exhibit more frequent and intensive repetitive behavior. For example, Lam et al. (2008) stated that there is a negative moderate relationship between intellectual competency and repetitive behaviors. Smith and Matson (2010) expressed that repetitive behaviors increase in cases where epilepsy accompanies ASD. Finally, in the literature, there are different findings in the studies exploring whether gender makes a difference in repetitive behaviors (Bourreau et al. 2009, Carcani‐Rathwell et al. 2006, Fulceri et al. 2016, Hartley and Sikora 2009, Lam et al. 2008, Mandy et al. 2012). For example, the studies of Carcani-Rathwell et al. Carcani-Rathwell et al. (2006) and Fulceri et al. (2016) revealed no significant difference between girls and boys with ASD in terms of repetitive behaviors. On the other hand, Mandy et al. (2012) and Hartley and Sikora (2009) put forth that boys exhibit more repetitive behaviors compared to girls. A meta-analysis study (Van Wijngaarden-Cremers et al. 2014) also stated that males exhibit more repetitive behaviors.

Other than the two basic diagnostic criteria, children with ASD experience different other problems such as cognitive (Doyle and Iland 2004, Happé and Frith 2006), sensory (Baranek 1999, Baranek et al. 2006, Chistol et al. 2018, Leekam et al. 2007) and sleep problems (Richdale and Schreck 2009). Apart from these, children with ASD frequently encounter motor problems (Dewey et al. 2007, Page and Boucher 1998). The studies comparing the motor performance of children with ASD and typically developing children revealed that the motor performance of children with ASD is significantly lower than their typically developing peers (Liu and Breslin 2013, Provost et al. 2007). This difference also appears in studies comparing children with developmental delays as well as typically developing children (Provost et al. 2007). Motor problems in individuals with ASD are evident from the early stages of life and continue in adolescence and adulthood (Teitelbaum et al. 1998). Moreover, what are the implications of the findings (Gima et al. 2018) for children with early motor delay is that there are very likely to meet diagnostic criteria of ASD in the future.

There are a limited number of studies (Radonovich et al. 2013, Uljarević et al. 2017) addressing the repetitive behaviors and motor problems together seen in children with ASD. Among them, Radonovich et al. (2013) aimed to explore the relationship between posture control, and repetitive behaviors. According to the findings, there were strong negative relationships between repetitive behaviors of children with ASD and posture control. Another study examined the predictiveness of the achievement times of early motor milestones (sitting, crawling, standing, and walking) on current repetitive behaviors of children with ASD. Determining the early motor milestones retrospectively, the study revealed that early motor milestones predicted repetitive behaviors strongly (Uljarević et al. 2017).

In order to get successful outcomes from interventions designed for repetitive behavior interventions in children with ASD, it is vital to identify the variables that affect or are associated with repetitive behaviors. In the literature on motor problems and repetitive behaviors, one study discussed posture control (Radonovich et al. 2013), and other discussed early motor milestones (Uljarević et al. 2017). In these studies, variables such as gender, age, and comorbidity that make a difference in repetitive behaviors were not taken into account (Radonovich et al. 2013, Uljarević et al. 2017). Thus, considering the limitations stated in the literature, the present study aimed to explore the effect of current motor coordination performance on repetitive behaviors in children with ASD. Within the framework of this general purpose, the answer to the following question is sought: ‘Do children with ASD with and without motor coordination problems differ in their repetitive behavior when age, comorbidity, and gender are taken under control?’

Method

Study group

The study was carried out with children with ASD aged 5–15 years who were getting services in special education schools and/or private special education and rehabilitation centers affiliated with the Ministry of National Education (MoNE) in Turkey and who were diagnosed from Department of Child and Adolescent Psychiatry of hospitals. While selecting the participants, purposive sampling was employed due to reasons such as accessibility and economy. Criterion sampling, one of the purposive sampling methods (Fraenkel et al. 2012), was used to determine the study group. For this purpose, the children diagnosed with ASD who attended special education schools and/or private special education and rehabilitation centers affiliated with the MoNE in Ankara, Turkey were reached. In the selection of these children reached for the study, the confirmation of the children’s ASD diagnosis with the Gilliam Autism Rating Scale-2-Turkish Version (GARS-2-TV), children being aged 5–15 years, children not having an additional diagnosis regarding the motor area, and parents giving their informed consent were taken as criteria. Data were collected from 270 children with ASD who met these criteria. However, 22 children (Autistic Disorder Index ≤ 69 points) whose diagnosis was not confirmed by GARS-2-TV were excluded from the study. In addition, the data obtained from a total of seven children were determined as outliers and were not included in the analysis. In this direction, information on the final study group included in the analysis is presented in Table 1.

Table 1.

Study group, GARS-2-TV standard scores and DCDQ-07-TV Scores (N = 241).

  Gender
 Comorbidity
 Age*
 Total
Female Male Yes No 5–712m 8–912m 10–15
  f 50 191 46 195 84 58 99  
  % 20.7 79.3 19 81 34.9 24.1 41.1  
GARS-2-TV M 26.15 27.56 26.72 26.38 25.05 25.85 27.98 26.44
SD 6.68 8.33 7.37 7.01 6.36 6.76 7.55 7.06
DCDQ-07-TV M 42.94 43.70 44.44 39.73 44.08 44.77 42.36 43.54
SD 15.93 12.99 13.48 13.66 12.88 13.83 14.13 13.61
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m: month.

*While forming the age groups, the grouping, which is used to determine the risk status according to age, was based on the Developmental Coordination Disorder Questionnaire-07-Turkish Version (DCDQ-07-TV) (Wilson et al. 2009).

According to Table 1, the number of boys participating in the study was approximately four times more than the number of girls. Considering the individuals with ASD, the literature stated that four out of every five people diagnosed are male (Baio et al. 2018). In the study, approximately 1/5 of the study group had comorbidity. A total of 59.3% (n = 27) had intellectual disability, 17.2% (n = 8) had epilepsy, 12.5% (n = 6) had language speech disorder and 11% (n = 5) had attention deficit and hyperactivity disorder. The literature revealed that individuals with ASD are accompanied by an additional diagnosis at higher rates (Demirkaya et al. 2016, Goldberg-Edelson 2006). In terms of the age variable, the ages for which DCDQ-07-TV can be administered were included in the study. Although the ranges of the age groups were different from each other, the group sizes did not differ much from each other.

Data collection tools

Demographic information form

Developed by the researcher, the form includes information on the parent and the child with ASD such as age, gender, comorbidity, weekly support education time. Forms were completed by the parents of children with ASD. The comorbidity, gender, and age characteristics in this form were included in the study analyses.

Gilliam autism rating scale-2-Turkish version (GARS-2-TV)

Administered to confirm the diagnosis of ASD in the present study, GARS-2-TV was developed by Gilliam (2006). GARS-2 aims to screen, diagnose, set goals and determine the severity of problem behaviors of individuals with ASD aged 3–23 years. The scale consists of 3 sub-scales, namely stereotyped behaviors (SB), communication (C), and social interaction (SI) areas. There are 14 items in each subscale and 42 items in total. The items are rated on a four-point Likert scale ranging from ‘never observed’ (0) to ‘frequently observed’ (3). The scale is completed by parents, caregivers, and teachers. The raw scores from the subscales are converted into standard scores, after which the total of the standard scores of the subscales are converted into Autism Disorder Index (ADI) and percentage rankings. A decision is made regarding the presence and severity of the ASD using the ADI decision guide. The standardization studies of the scale were conducted by Diken et al. (2012). The fit indices were between acceptable and perfect values based on the confirmatory factor analysis (CFA) performed for construct validity. In addition, the differential validity of the scale was conducted with other types of disabilities and typically developing children. The scale differentiated ASD from other disabilities and typically developing children. The correlation coefficients (SB-r = .98, C-r = .99, SI-r = .99) obtained in test-retest reliability were quite high. Finally, the Cronbach’s alpha internal consistency coefficients (α) were .79, .77, .85 for the subscales, respectively, and .88 for the total scale (Diken et al. 2012). In the present study, the Cronbach’s alpha internal consistency coefficients of GARS-2-TV completed by the parents were α = .84, α = .82, α = .85 for the subscales, respectively, and α = .90 for the scale total score.

Repetitive behavior Scale-Revised-Turkish version (RBS-R-TV)

Developed by Bodfish et al. (2000) to evaluate the intensity and variety of repetitive behaviors seen in ASD, the RBS-R was used in this study to evaluate repetitive behaviors. On the scale, the repetitive behaviors were classified as stereotypic behaviors (6 items), self-injurious behaviors (8 items), compulsive behaviors (8 items), ritualistic behaviors (6 items), sameness behaviors (11 items), and restricted behaviors (four items). Completed by the parents, the scale items are rated from 0 to 3 (0 = none, 1 = mild, 2 = moderate, and 3 = severe). The scores from the subscales and the scale total can be used in the interpretation of repetitive behavior individually (Bodfish et al. 2000, Lam and Aman 2007). As the scores from the scale increase, the intensity and variety of repetitive behaviors increase. Used in many studies (Boyd et al. 2009, Chowdhury et al. 2010, Cuccaro et al. 2007, Wolff et al. 2014), RBS-R was adapted into Turkish by Ökcün-Akçamuş et al. (2019). During its adaptation into Turkish, the construct validity was examined using CFA, and the fit indices were at acceptable and perfect levels. Therefore, the six-factor structure was confirmed. The differential validity of the scale was examined with the data collected from individuals with intellectual disabilities, and it was determined that the scale differentiated ASD and individuals with intellectual disabilities. The criterion validity was examined with GARS-2-TV, and the correlation coefficients were found between medium and high levels. The internal consistency coefficients were examined within the scope of reliability, and the internal consistency coefficients were found as α = .74, α = .73, α = .77, α = .73, α = .87, α = .78 for the subscales, respectively, and α = .94 for the total scale (Ökcün-Akçamuş et al. 2019). In the present study, the internal consistency coefficients were determined as α = .81, α = .88, α = .77, α = .74, α = .88, respectively, and α = .73 for the total scale.

Developmental coordination disorder questionnaire-07-Turkish version (DCDQ-07-TV)

In this study, DCDQ-07-TV, developed by Wilson et al. (2009), was used to assess the motor coordination in children with ASD. The questionnaire was developed to determine daily functions in three sub-areas (control during movement, fine motor, general coordination) in children aged 5–15 years. The 15 items are rated on a five-point scale ranging from 1 to 5 (1 = not similar, 5 = very similar). The tool is filled by the parents. Maximum 75 points can be obtained from the tool. DCDQ-07 divides children aged 5–15 years into three age groups (5–711m, 8–911m and 10–15). There are cut-off scores (5–711m = 46, 8–911m = 55 and 10–15 = 57) in terms of motor performance according to these age groups. Sensitive to intercultural differences (Ghanizadeh 2010, Kennedy-Behr et al. 2013, Prado et al. 2009, Wilson et al. 2009), the questionnaire's Turkish validity and reliability works were conducted by Yıldırım et al. (2019). As a result of the exploratory factor analysis (EFA), unlike the original, a two-factor structure (gross motor-eight item, fine motor and static position-seven item) was obtained, and this structure was confirmed by CFA. The fit indices obtained from CFA were between acceptable and excellent levels. The internal consistency calculation for the total score of the scale was α = .90. In the present study, these values were α = .87 for the gross engine sub-dimension of DCDQ-07-TV, α = .85 for the fine motor and static position, and α = .92 for the total score were obtained.

Data collection

Before collecting the study data, the necessary approval was obtained from the Ethics Committee of Ankara University, regarding the compliance of the study with ethical rules (Date: 04.03.2019, Number: 3/78). Then, research permission was obtained from the Ankara Provincial Directorate of National Education, schools, and institutions to collect data. During data collection, interviews were conducted by making appointments with school or institution administrators so that children in schools can be included in the study. During the interviews, the administrators were informed about the study purpose, and the necessary permissions were obtained. With the direction of the administrators, families of children with ASD were reached. Parents were interviewed in line with the determined criteria. Then, parents’ informed consent was taken for them to be included in the study. After these procedures, the relevant data collection tools to be used in the study were delivered to the parents through the teachers, and they were asked to fill them with no items left blank. Completed data collection tools were collected from schools or institutions by appointment.

Data analysis

The analysis of the data was carried out using the R package program. First, ASD diagnosis was confirmed by converting the raw scores obtained from GARS-2-TV to the standard scores, and then to ADI. Then, for the first study question, descriptive analyses were performed for repetitive behaviors and motor coordination and the scores obtained from their sub-dimensions. Afterward, in line with the scores obtained from DCDQ-07-TV, children with ASD were divided into two groups according to their cut-off scores: Risk for DCD and no risk for DCD. In addition, the groups were approximately four to one in terms of the presence of DCD, as in the gender and comorbidities of the children in the study group. However, it is stated that when the number of individuals in one group is up to four times the other group, the difference between the groups can be examined and that there is no need to select samples from the larger group (Tabachnick and Fidell 2013).

Firstly, the univariate normality assumptions were examined. According to the descriptive statistics (RBS-R-TV, range = 0–94, skewness = .89, kurtosis = .28; DCDQ-07-TV, range = 15–75, skewness = -.08, kurtosis = -78) and graphical readings, the data met the univariate normality assumptions. Then, whether the multivariate statistical assumptions were met or not was examined. Since the residual values (DWT-Stereotypic = 1.88, DWT-Self-injurious = .85, DWT-Compulsive = 1.93, DWT-Ritualistic = 1.99, DWT-Sameness = 1.86, DWT-Restricted = 1.93, DWT-RBS-R-TV = 1.88) obtained from the Durbin Watson Test (DWT) performed to test is the error independence were within the desired limits (Griffiths et al. 1993), it was determined that there was no autocorrelation problem. According to the significance levels (p > .05) obtained from the Levene test conducted to test the homogeneity of variances, the assumption of homogeneity of variances was met for all sub-dimensions and total score. Chi-Square analysis was performed to test whether there was a relationship between covariates. According to chi-square analysis there was no relationship between comorbidity and age (Chi-square = 6.34, df = 2, p > .05), comorbidity and gender (Chi-square = 3.24, df = 1, p > .05) and age and gender (Chi-square = 2.19, df = 2, p > .05). After meeting the multivariate statistical assumptions, a Multivariate Analysis of Covariance (MANCOVA) was performed to test whether there was a change in the repetitive behaviors of children with ASD when age, gender, and comorbidity variables were controlled in the theoretical framework.

Findings

In the study, first, the repetitive behaviors and motor coordination performances of children with ASD were examined by looking at descriptive statistics. The children with ASD had a mean score well above the minimum scores that could be obtained in all dimensions of repetitive behaviors (see Table 2). In addition, due to the nature of the ASD, at least one repetitive behavior structure was present in the entire study group. The mean scores of children with ASD (N = 241) for the gross motor area from the sub-dimensions of DCDQ-07-TV were 24.01 and 19.53 for the fine motor and static position area, respectively. These values are well below the maximum points that can be obtained. The mean scores of children with ASD in all age groups were below the cut-off scores (See Data Collection Tools) (5–711m = 44.1, 8–911m = 44.7, 10–15 = 42.3). According to the data collected, in line with the DCDQ-07-TV cut-off scores, 46 (54.8%) children within the 5–711m age range (n = 84), 43 (74.1%) children within the 8–911m age range (n = 58), and 84 (84.9%) children within the 10–15 age range (n = 99) were found to be at risk of DCD. In total, 173 (71.8%) children with ASD had DCD risk.

Table 2.

Repetitive behaviors’ descriptive statistics.

Repetitive Behaviors Motor coordination disorder n X¯ SS
SB1,* Absent 68 3.97 3.28
Present 173 6.16 4.08
Total 241 5.55 3.99
SIB2,* Absent 68 2.13 4.30
Present 173 3.64 4.67
Total 241 3.22 4.61
CB3 Absent 68 4.94 4.02
Present 173 5.97 4.42
Total 241 5.68 4.33
RiB4 Absent 68 5.08 3.79
Present 173 5.20 3.71
Total 241 5.17 3.73
SaB5,* Absent 68 7.39 6.67
Present 173 9.85 6.67
Total 241 9.16 6.74
ReB6 Absent 68 3.47 3.08
Present 173 4.12 2.80
Total 241 3.93 2.89
RBS-R-TV7,* Absent 68 27.00 20.11
Present 173 34.95 20.46
Total 241 32.71 20.64
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1Stereotypic Behavior, 2Self Injuries Behavior, 3Compulsive Behavior, 4Ritualistic Behavior, 5Sameness Behavior, 6Restricted Behavior, 7Repetitive Behavior Scale-Revised-Turkish Version Total.

*The behaviors in which a significant difference was observed according to the MANCOVA findings.

In the context of the study, the data on the means and standard deviations obtained from the repetitive behaviors and sub-dimensions of the DCD present and DCD absent groups which were formed according to the DCDQ-07-TV performances of children with ASD are presented in Table 2. Table 2 shows that children with ASD who had motor coordination disorder had higher mean scores in all sub-dimensions and total score of repetitive behaviors.

In order to answer the main study question, MANCOVA was performed to test whether the significant difference occurred according to the presence of DCD after age, gender, and comorbidity, which are stated to be effective on repetitive behaviors in the literature, were controlled. The MANCOVA result revealed that even when the variables of age, comorbidity, and gender were taken under control, at least one of the repetitive behavior sub-dimensions or repetitive behavior total scores of the groups significantly differed according to the presence of DCD (Pillai’ Trace = 0.074, F(7,233) = 2.628, p < .05). According to the MANCOVA outputs, there was no significant difference between the groups in terms of compulsive behavior (F(1,236) = 2.103, p > .05), ritualistic behavior (F(1,236) = .077, p > .05), restricted behavior (F(1,236) = 2.783, p > .05) if there is the presence of the DCD risk or not. However, stereotypic behavior (F(1,236) =12.903, p < .05), self-injurious behavior (F(1,236) =4.939, p < .05), sameness behavior (F(1,236) = 4.494, p < .05), and RBS-R-TV (F(1,236) = 6.113, p < .05) differed significantly between groups. According to the calculated effect size for the repetitive behaviors with differentiation had a small effect (stereotypic behavior adjusted R2 = .06, self-injurious behavior adjusted R2 = .02, sameness behavior adjusted R2 = .03, RBS-R-TV total adjusted R2 = .03).

Discussion, conclusion, and recommendations

The main purpose of this study was to examine the effect of motor coordination performance on repetitive behavior of children with ASD. In this direction, the repetitive behaviors and motor coordination performances of children with ASD were examined. According to the findings, at least one of the repetitive behaviors was present in children with ASD, but its severity and variety differed. The studies examining repetitive behaviors that are directly proportional to the severity level of ASD (APA 2013) revealed that as the severity level of ASD increases, the severity and variety of repetitive behaviors increase (Boyd et al. 2009, Cuccaro et al. 2007). Cuccaro et al. (2007) also used the RBS-R in their study, and the mean scores of children with ASD regarding repetitive behaviors and its sub-dimensions are in line with this study. Therefore, according to the findings of this study and other studies, it can be said that children with ASD aged 5–15 years have repetitive behaviors and are similar in different cultures (Boyd et al. 2009, Cuccaro et al. 2007, Lewis and Bodfish 1998).

The examination of the motor coordination performances of children with ASD concluded that their performances in gross motor and static position and fine motor performance were quite low. In addition, the mean scores obtained from the sub-dimensions were below the cut-off scores in all age groups. Moreover, approximately 3/4 of the children with ASD had DCD risk according to the DCD presence status formed in line with these cut-off scores (see Table 2). This rate indicated the majority of children with ASD. Previous studies stated that the motor performance of children with ASD is much more restricted than their typically developing peers (Liu and Breslin 2013, Provost et al. 2007). Regarding the prevalence of motor problems, Gillberg (1989) reported rates at 83%, Green et al. (2009) at 79%, and Klin et al. (1995) at 90%. Belaire et al. (2020) Gabriel, more specifically, stated that 79% of the children with ASD in the study group had severe and 14% had moderate motor difficulties, and only 7% did not have any difficulties. Unlike these studies, Kopp et al. (2010) stated that 45% of children with ASD, a relatively low rate, had motor problems. However, the fact that Kopp et al. (2010) conducted their study solely with girls with ASD and performed the medical motor evaluation may be the reason for this differentiation. Thus, the studies in the literature and the present study indicate that motor problems are common in children with ASD. The meta-analysis study carried out by Fournier et al. (2010) also revealed that the motor coordination deficiencies seen in ASD are one of the basic characteristics of ASD.

When age, gender, comorbidity were taken under control whether the repetitive behaviors and sub-dimensions of children with ASD differed according to DCD presence was examined. The results put forth that the presence of DCD in children with ASD did not make a significant difference in repetitive behaviors, namely compulsive behavior, restricted behavior, and ritualistic behavior. On the other hand, the presence of DCD caused a significant difference in the total scores of stereotypic behavior, self-injurious behavior, sameness behavior, and the total of RBS-R-TV. In other words, stereotypic behavior, self-injurious behavior, sameness behavior, and general repetitive behaviors of children with DCD were found to be more various and intense. In other words, motor coordination performance was effective on these repetitive behaviors, regardless of age, gender, and comorbidity variables. The literature stated that compulsive behavior is seen in other developmental disability groups independent of ASD and thus these behaviors can be explained by the intellectual performance (Evans and Gray 2000). Gabriels et al. (2005) reported findings supporting this. In terms of restricted behavior and ritualistic behavior, these behaviors are associated with psychiatric symptoms in addition to intellectual performance (Gabriels et al. 2005, Stratis and Lecavalier 2013). Therefore, it is possible to state that other variables than motor coordination are effective on these behaviors. Miyachi et al. (2014) suggested that children with ASD are inversely proportional to their stereotypic behavior intensity and their motor coordination performance. In addition, the study conducted by Radonovich et al. (2013) showed that the increase in the restrictions in posture control of children with ASD leads to an increase in the intensity of stereotypic behavior, compulsive behavior, restricted behavior, and sameness behavior. Problems experienced in posture control constitute an important difficulty especially in performing gross motor skills. For example, a defect in posture control will make it difficult for the child to perform a skill using a ball correctly. So much so that clumsiness, which is frequently mentioned with both posture control and motor coordination, is associated with self-injurious behavior (Travers et al. 2013). The findings of previous studies and the present study revealed that the repetitive behaviors of children with ASD are not independent of their motor performance. In this respect, since motor coordination problems witnessed in children with ASD reduce the possibility of exhibiting desired behaviors, this can be presented as a reason for the increase in the variety and intensity of repetitive behaviors.

The present study showed that covariants did not cause any differentiation in repetitive behaviors. Yet, the literature argued that the repetitive behaviors of children with ASD differ according to age (Esbensen et al. 2009, Militerni et al. 2002), comorbidity (Bishop et al. 2006, Bourreau et al. 2009, Lam et al. 2008), and gender (Hartley and Sikora 2009, Mandy et al. 2012). The differentiation in the findings of the present study and the related literature can be explained by several reasons. The first is that Esbensen et al. (2009), in their study using past research data, addressed age groups with a wide range (2–51+). In the study of Militerni et al. (2002), a difference was found between 2–4 years and 7–11 years. Since DCDQ can be administered to children aged 5–15 years, only this age group was studied in the present study. Moreover, the study of Esbensen et al. (2009) suggested that repetitive behaviors decrease in young adulthood and during adulthood. Therefore, it is possible to say that the difference in the present study may be due to this and that the repetitive behavior profiles of children with ASD may be close to each other in the 5–15 age range. In terms of comorbidity, the additional diagnosis of children with ASD was determined with the information obtained from their parents in the present study, and no additional diagnosis confirmation was made. Considering the agreement in the literature regarding the negative relationship between intellectual competency and repetitive behaviors, it was expected that the repetitive behaviors of children with intellectual disabilities in addition to ASD would be more intense. However, the fact that only 1/5 of the current study group had an additional diagnosis and it consisted of different additional diagnoses (intellectual disability, epilepsy, etc.) may be the reason for this situation. When all these are taken into consideration, it can be said that the total of stereotypic behavior, self-injurious behavior, sameness behavior, and repetitive behaviors in children with ASD aged 5–15 years are more various and intense than those who do not have DCD.

The present study has some limitations. First, the confirmation of the diagnosis of ASD and the assessment of repetitive behaviors and motor coordination in the study was based solely on parental views. In other words, clinical assessments could not be conducted. Furthermore, the fact that DCDQ-07-TV, one of the assessment tools, was developed for children aged 5–15 years, caused individuals with ASD of different ages to not be included in the study. Another limitation is the reporting of the additional diagnosis of children with ASD was made in line with the information obtained from the parents.

As a result, repetitive behaviors in children with ASD aged 5–15 years show variety and differ in terms of intensity and severity. In terms of motor coordination, both their gross motor and fine motor and static position performances are quite restricted. In addition, the motor coordination performances of children with ASD at all ages are well below the norm scores. Moreover, it is possible to mention the presence of DCD in most children with ASD. Finally, the repetitive behaviors witnessed in children with ASD diversify and intensify in the presence of DCD. This situation points out that the existence of DCD should be taken into consideration in planning the services to be offered to children. From this point of view, it is recommended that practitioners make assessments in the motor coordination area in children with ASD. Furthermore, when considered independently from repetitive behaviors, restrictions in the motor area are seen in the majority of the population. Considering the effects of the restrictions experienced in the motor area on the quality of life, this area cannot be ignored. In this context, planning activities supporting motor coordination in children with ASD are recommended to practitioners and teachers. In addition, although there are studies examining the effect of motor exercises on repetitive behaviors that reveal the causality relationship with experimental evidence (Moradi et al. 2020), the number of intervention programs for repetitive behaviors mediated by motor coordination skills can be increased and their effectiveness can be tested. Finally, future studies can be conducted with wider age groups to confirm comorbidity.

Disclosure statement

No potential conflict of interest was reported by the authors.

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