Mindfulness for children and adolescents with autism spectrum disorder : the effect on attention networks

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Faculty of Social and Behavioural Sciences

Graduate School of Child Development and Education

Mindfulness for Children and Adolescents with Autism Spectrum

Disorder: the Effect on Attention Networks

Research Master Child Development and Education Research Master Thesis

Research Master Student: Sanne van den Driesschen, 11042494

Names of the supervisors: Anna Ridderinkhof, MSc & Prof. Dr. Susan Bögels Date: January 30th, 2018

Word Count Abstract: 254 Word Count: 8693

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Abstract

Mindfulness Training has a growing body of research as an intervention for children and adolescents with Autism Spectrum Disorder (ASD). Most mindfulness-based practices target the self-regulation of attention. Attention can be conceptualized as three independent attention networks: alerting, orienting, and executive attention. Research suggest that children and adolescents with ASD show atypical attention, and have less efficient attention networks compared to typically developing (TD) children and adolescents. Mindfulness Training might improve the cognitive mechanism of attention and therefore positively change attention networks in children and adolescents with ASD. In this study, we investigated

whether children and adolescents referred with ASD (N = 51) differ in attention networks compared to TD children and adolescents (N = 51) . Besides that, we investigated whether the MYmind program for children and adolescents with ASD positively affects attention

networks in these children and adolescents with ASD. We expected that children and adolescents with ASD had a less efficient orienting and executive network, but that their efficiency improves towards the efficiency of TD children and adolescents after 9 weeks of Mindfulness Training and that this improvement remains at a 9 week Follow-up. Attention networks are measured with the child version of the Attentional Network Test (ANT). Opposite to the hypotheses, results indicate that children and adolescents with and without ASD do not differ in attention networks. Furthermore, Mindfulness Training did not improve attention as measured by the ANT in children and adolescents with ASD. Implications of the results and suggestions for future research are discussed.

Keywords: Autism Spectrum Disorder, Attention Networks, Mindfulness Training, Attention Network Test

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Introduction

Autism Spectrum Disorder (ASD) is a life-long neurodevelopmental disorder, characterized by deficits in social communicative and cognitive functioning and restricted, repetitive patterns of behavior, interests, or activities (American Psychiatric Association, 2013). The worldwide prevalence of ASD is estimated on one child out every 162 (0.62%) and increases every year (Elsabbagh et al., 2012). Besides the aforementioned core symptoms of ASD, children with ASD often suffer from comorbid problems such as anxiety, depression and aggression (Sighn et al., 2014). One of the cognitive processes that might underlie the abovementioned core symptoms, is an atypical attention (Belmonte & Yurgelun-Todd, 2003; Zwaigenbaum et al., 2005). Children with ASD often have difficulties to disengage attention away from a specific target (Bryson et al., 2017). To be able to engage attention to a new stimulus or target, a child must first disengage its attention away from a current focus, and then shift its attention to this new stimulus or target (Zwaigenbaum et al., 2005). Because children with ASD often lack the ability to disengage attention, these children have a reduced tendency to shift and attend to changing and novel stimuli. Besides that, children with ASD are less reactive to social relevant stimuli and are unable to filter information that is irrelevant. Therefore, children with ASD have difficulties paying attention to social and non-social environmental information, and they might be easily distracted by irrelevant stimuli (e.g. noise, light, moving objects) (Keehn, Nair, Lincoln, Townsend, & Müller, 2016;

Zwaigenbaum et al., 2005). While different brain areas are associated with the difficulties in attention, the underlying mechanisms and processes that cause these difficulties remain unclear (Farrant et al., 2016). However, an atypical attention is one of the first noticed characteristics to distinguish infants who are later diagnosed with ASD, and therefore it is useful to gain more knowledge about attention in children with ASD (Zwaigenbaum et al., 2005).

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Though ASD is a lifelong disorder, there is growing interest in Mindfulness Training as an intervention for children and adolescents with ASD to help them overcome some difficulties. According to Kabat-Zinn (2009) mindfulness means paying attention in a certain way: on purpose, in the present moment, and nonjudgmentally. Most mindfulness-based practices use a form of meditation which contains many techniques for the self-regulation of attention (Semple, 2010). Mindfulness Training focuses on increasing the ability to control attention and on reducing automatic responses. Besides that, Mindfulness Training focuses on repeatedly engaging, shifting, and disengaging attention (Jha, Krompinger, & Baime, 2007). Therefore, it might be that Mindfulness Training alters specific aspects of attention and improve the efficiency of subsystems of attention (Jha et al., 2007).

While there are several descriptions of attention, Posner and Petersen (1990) proposed a useful and coherent framework for explaining and identifying the mechanisms of attention that can be used for an atypical as well as a typical developing population. In this framework, attention is conceptualized as three independent attention networks: alerting, orienting, and executive control. These three networks are related to different sets of cognitive processes. First, alerting attention is the ability to prepare and sustain alertness to process high priority signals. This network is responsible for maintaining a state of sensitivity to the detection of environmental events (Mutreja et al., 2016; Posner & Petersen, 1990). Second, orienting attention is concerned with the shifting of attention to environmental cues. This involves the ability to disengage attention away from one stimulus and on to another, shifting attention between two stimuli, and the ability to re-focus on new stimuli occurring in the environment. Third, the attention network executive control is responsible for monitoring and resolving processing conflict among competing sources of input (Posner & Petersen, 1990). The three networks of attention in children can be measured with the child version of the Attention Network Test (ANT) (Rueda et al., 2004).

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The ANT is a computerized task in which the efficiency of the alerting network, the orienting network and the executive control network are measured with help of reaction time (RT) and accuracy (Rueda et al., 2004). There are only a few studies that used the ANT to examine attention networks in children with ASD. In one study, fifty-two TD children and 14 children with ASD, between 5 and 11 years of age, performed the child version of the ANT (Mutreja et al., 2016). It was found that TD children and children with ASD did not show any differences in efficiency of the alerting network. However, compared to TD children, children with ASD exhibited a less efficient orienting attention, as visible in the pattern of mean RT difference scores. Children with ASD had a higher mean RT, which indicates that children with ASD failed to benefit from the presentation of a spatial cue and struggle with shifting their attention away from a central fixation to a stimulus appearing in a spatially cued location. Perhaps children with ASD have difficulties in maintaining a large enough attentional span to process both central and peripheral sources of information at the same time. Finally, when investigating efficiency of the executive attention, children with ASD and TD children did not show any differences in mean RT, but children with ASD had a

significant higher error rate than TD children. This result shows that children with ASD might be less able to ignore incongruent directional information (Mutreja et al., 2016), which

indicates difficulties with ignoring irrelevant information.

The findings of Mutreja and colleagues (2016) suggest that children with ASD have a less efficient orienting and executive network compared to TD children. However, other research found different results. In one study, 20 children with ASD and 20 TD children between the ages of 8-18 performed the child version of the ANT (Keehn, Lincoln, Müller, & Townsend, 2010). After finding a significant difference between the children with ASD and TD children, results only showed a less efficient orienting network for the children with ASD. In another study where 14 adults with ASD and 14 healthy adults performed the ANT, adults

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with ASD and healthy adults differed on the ANT scores Fan et al., 2012). The adults with ASD showed a less efficient executive network compared to the healthy adults. Furthermore, when comparing the two groups on accuracy, the adults with ASD made significantly more errors than the healthy adults in the alerting network. However, the difference in overall RT was not significant (Fan et al., 2012).

Besides research that investigated the attention networks in children and adults with ASD, there is no research yet that explores the effect of Mindfulness Training on attention networks of children and adolescents with ASD and TD children and adolescents. However, research suggests that Mindfulness Training might enhance the self-regulation of attention, by training attentional aspects such as focusing, switching and dividing attention (Shapiro, Carlson, Astin, & Freedman, 2006). In a study that explored the relation between Mindfulness Training and attention in a non-clinical population of adults, the attention networks as

measured with the ANT are investigated in mindfulness meditators compared to an age and gender matched control group (Van der Hurk et al., 2010). Results indicate that adults that meditate show a significant more efficient orienting and executive network than adults that do not meditate (van der Hurk et al., 2010). These networks are exactly the ones that were found to be impaired in children with ASD (Mutreja et al., 2016). Other research investigated the effect of Mindfulness Training and attention as measured with the ANT among adults (Jha et al., 2007). Participants were randomly allocated to a Mindfulness Training group, a retreat group, and a control group. Participants performed the ANT at Pretest and Posttest, with approximately 8 days between measurements. Results show that participants in the Mindfulness Training group significantly improved their scores on the orienting network, meaning their orienting network became more efficient with help of Mindfulness Training (Jha et al., 2007).

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Based on the aforementioned results it might be expected that Mindfulness Training for children and adolescents with ASD positively alternates their attention networks. Since only a few studies focused on the attention networks of children with ASD and there is no research yet that explores the effect of Mindfulness Training on the attention networks of children and adolescents with ASD measured with the ANT, we investigated whether (1) there are differences in the three attention networks measured with the child version of the ANT in children and adolescents (9-23 year) with ASD compared to TD children and adolescents at Pretest, but not after 9 weeks Mindfulness Training for children and adolescents with ASD, and (2) if the effect of Mindfulness Training on the three attention networks in children and adolescent with ASD remains after 9 weeks.

Since recent findings indicate that children with ASD have a less efficient orienting and executive network compared to TD children (Mutreja et al., 2016), and that adults who meditate have a significant more efficient orienting and executive network compared to adults that do not meditate (van der Hurk et al., 2010), it might be that Mindfulness Training can change these specific attention networks. It is therefore expected that children and adolescents with ASD show different attention scores on the ANT compared to TD children and

adolescents before Mindfulness Training. These differences will be visible in a less efficient orienting network, and a less efficient executive network as reflected by a higher median RT for children and adolescents with ASD compared to TD children and adolescents. It is expected that there will be no differences in the alerting network in children and adolescents with ASD compared to TD children at Pretest and Posttest measurement. In addition, it is expected that children and adolescents with ASD improve their orienting network efficiency and their executive control network efficiency as measured with the ANT after 9 weeks of Mindfulness Training. It is expected that these improvements remains 9 weeks after the last session of Mindfulness Training. Results are interpreted as positive when ANT scores for

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children and adolescents with ASD improve towards the performance of TD children, who do not receive any Mindfulness Training. Understanding of the different attention networks in children and adolescents with ASD may provide insight in the impairments of attentional development in ASD and how these impairments can be improved trough Mindfulness Training.

Method Participants

For the first research question, an a-priori analysis, using G*Power 3.1 (Faul, Erdfelder, Buchner, & Lang, 2009) indicated a sample size of N = 34 to detect a significant effect with a power of .80, an α = .05 as criterion for significance, and a medium effect size f = 0.25. For the second research question, a total sample size of N = 36 is needed for 80% power to detect a medium effect size of f = .25 when using an α = .05 as criterion for significance.

The participants in the experimental group were 51 children and adolescents with ASD from the ages of 9-23, who participated in the ‘Mindfulness in Child and Adolescent

Psychiatry’ study (METC protocol, 2013). Participants in the experimental group were referred to the Academic Treatment Centre for Parents and Children (UvA Minds) for

presence of ASD, who were indicated for Mindfulness Training. Children and adolescents and their parents were informed about the research around Mindfulness Training. Individuals eligible for participation received an information letter and were asked by phone by Psychology and Pedagogics Master students to participate in the study. Participants in the experimental group attended 9 weeks of Mindfulness Training. Inclusion criteria for the participants in the experimental group were a DSM-IV diagnosis of ASD, an IQ > 80, ability to attend the first Mindfulness Training session, attending a minimum of at least 6 out of 8 sessions, and participants had to be between 9 and 12 years old (children group; elementary

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school) or between 12 and 23 years old (adolescent group; secondary school or beyond). Participants for the experimental group were excluded when they had an inadequate mastery of the Dutch language, severe behavioral problems as indicated by a CD on the ADIS-C, comorbid developmental disorder, and when they were participating in another ongoing psychological intervention.

Participants for the control group were 51 children and adolescents recruited via primary schools and secondary schools. Adolescents older than 18 year were recruited using snowball sampling by means of the network of the researchers conducting this study. Principals received a letter in which information about the study was described. When

permission was given to recruit participants at their school, children and adolescents received a letter with information about the study and informed consent. Participants also filled in a few questions about their age, educational level, and if they are diagnosed with a

developmental disorder. Inclusion criteria for the participants in the control group was an age between 9 and 23 year. Exclusion criteria were an inadequate mastery of the Dutch language and a developmental disorder as indicated by one of the questions that the participants filled in before participating in the study. The ASD group and the control group were matched on age, educational level, and gender at group level. Educational level is described by using the Dutch school level division based on CITO-results for grades 5, 6, 7, and 8, the ‘Entreetoets' for grade 7, or the final CITO test for grade 8. Based on their school performance level, children and adolescents were divided into three groups: ‘VWO/Gymnasium’, ‘HAVO’, ‘VMBO’. The division based on school performance level is provided on the CITO-website and the website of the Ministry of Education, Culture, and Science.

Before participating in the study, children of 12 years old and above gave written informed consent. For children between 9 and 16 years old, parents also gave written informed consent. In the ASD group, informed consent was obtained from all parents of all

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children, regardless of age. All children and adolescents received a small present after each measurement occasion. The study was approved by the Ethics Review Board of the Child Development and Education department of the University of Amsterdam.

Mindfulness Training

Children and adolescents with ASD visited the UvA Minds Centre where they

attended 9 weekly group sessions of Mindfulness Training (MYmind program) in groups of 4 to 6 participants, 1.5 hours per week. Mindfulness Training was delivered by an experienced mindfulness trainer, and the training was inspired by a mindfulness program specially developed for individuals with ASD. The training consisted for example of less verbal instructions, and the mindfulness trainer used more direct language.

Design

To investigate if children and adolescents with ASD and TD children and adolescents differ in attention networks before the Mindfulness Training for children and adolescents with ASD, but not after the training, ANT measurements of two time points were used (Pretest and Posttest). The time between the two measurements varied between four and five weeks for the control group to nine weeks for the experimental group. TD children and adolescents did not wait for 9 weeks because of practical reasons. TD children and adolescents did not receive Mindfulness Training, but performed the ANT twice to control for the possibility of a learning effect and changes over time. To our knowledge, there is only one study that investigated learning effects of the ANT. In this study, learning effects were found for the orienting and executive network (Ishigami & Klein, 2009). However, the study only consisted of 10 participants from the age of 18 to 39, who each performed the ANT 10 times with

approximate 8 days between measurements. In our study, participants perform the ANT only two or three times with 4-5 or 8-9 weeks in between, and therefore we do not expect a

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over time. If there is no difference in attention network scores measured with the ANT in the control group between Pretest and Posttest, there is no learning effect.

To answer the question if the effect of Mindfulness Training on attention networks remains, children and adolescents with ASD performed the ANT three times: at Pretest, Posttest, and Follow-up. There are 9 weeks between each measurement occasion, and children and adolescents with ASD received 9 weeks of Mindfulness Training between pretest and posttest.

Figure 1. Study design

Measurement

To measure the three attention networks alerting, orienting and executive control, children and adolescents in the ASD group and control group performed the child version of the ANT (Rueda et al., 2004; Figure 2). Participants first received a verbal instruction

followed by 24 practice trials and three blocks of 48 experimental trials (5 minutes per block). Participants are instructed to ‘feed the fish’ by pressing the mouse button that matches the direction that the centre target fish is facing.

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Each trial begins with a central fixation cross followed by one of four attentional trial types in equal proportions: no cue, a centre cue, a double cue and a spatial cue. On no cue trials, the fish will appear alone. In the centre cue, an asterisk is presented at the same location as the central fixation cross before the fish appears. In the double cue, an asterisk is presented simultaneously above and below the central fixation cross before the fish appears. In the spatial cue, a single asterisk is presented at the same position as the upcoming target fish, before the fish appears. In trials to assess executive control, flanker fish appear on the left and right side of the target fish, and are oriented in either a congruent, incongruent or neutral way. The three attention networks are calculated by subtracting the RT’s for the more simple trials from the RT’s for the more difficult trials. The alerting network is calculated by subtracting the RT’s for double cue trials from the RT’s for no cue trials. The orienting network is calculated by subtracting the RT’s for spatial cue trials from the RT’s for centre cue trials. The executive network is calculated by subtracting the RT’s for congruent trials from the RT’s for incongruent trials.

Participants have 1700 ms to respond, after which they receive visual and auditory feedback from the computer. After each correct response, an animation of the target fish blowing bubbles is showed and a sound of ‘whoohoo’ is played. Incorrect responses are followed by a numb tone and no animation. Accuracy and reaction times (RTs) are recoded via E-Prime v.1.0, which is a software package. E-Prime provides millisecond precision timing to ensure accuracy of the data.

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Figure 2. The child version of the Attention Network Test (Rueda et al., 2014). Procedure

Children and adolescents performed the ANT on a computer. For every participant, each session took between 20 and 30 minutes. For each session, the researcher gave a verbal instruction with help of small cards with the different conditions of the target fish. Children and adolescents in the ASD group performed the test at the UvA Minds Centre, in a quiet room. Children and adolescents in the control group performed the test in a quiet room at their own school, or at home.

Statistical Analyses

Data were analyzed using the Statistical Package for the Social Sciences (SPSS) version 23. In order to answer the first research question ‘are there differences in the attention networks measured with the child version of the ANT in children and adolescents with ASD compared to TD children and adolescents before Mindfulness Training, but not after

Mindfulness Training?’ the data was evaluated using multilevel data analysis for scores on the ANT at Pretest and Posttest. For each attention network (alerting, orienting, and executive

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control) a model was created, with the ANT scores as the dependent variable, with group (ASD/control) placed at the higher level, and time (Pretest and Posttest) as the lower-level variable. Besides that, an interaction for group x time was included in the model.

For the second research question, ‘Does the effect of Mindfulness Training on the attention networks in children and adolescents with ASD remain after 9 weeks’? data for the experimental group was analyzed using multilevel data analysis for scores on the ANT at Pretest, Posttest, and Follow-up. A model was built with the ANT scores as the dependent variables, with group placed at the higher-level, and time (Pretest, Posttest, and Follow-up) as the lower-level variable. In order to investigate if the children and adolescents with ASD performed differently on the three time points, time measurement Follow-up was used as baseline. In this way, it can be investigated if children and adolescents with ASD change in attention networks from Pretest to Follow-up and from Posttest to Follow-up.

Standardized parameter estimates for evaluating the size of effect were used, where

negligible < 0.2 < small < 0.5 < moderate < 0.8 < large (Cohen’s d). Results

Robustness

In order to investigate whether the data is robust, we checked the attention network scores on outliers (i.e., -3.29 > z-value > 3.29) and on negative attention network scores. When an attention network score is negative, it means that an individual performs more slow than expected on the simple trial compared to the other, more difficult trial. This might indicate an individual is not paying attention to the test or is not motivated. Only two outliers were found on the executive network. Besides that, some negative network scores were found. We reanalyzed the data by removing these outliers and negative attention scores from the data. Results remained similar, and therefore we did not remove any outliers or negative network scores in the final analyses.

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Descriptive Statistics Age, Gender, and Educational Level

To check whether the groups were matched correctly on group level, data from all children and adolescents (N = 102) who participated in the study was analyzed. At Pretest, children and adolescents in the ASD group (N = 51; 42 boys and 9 girls) had a mean age of 12.96 years (SD = 3.23). Children and adolescents in the control group (N = 51; 40 boys and 11 girls) had a mean age of 13.00 years (SD = 3.10) at Pretest. An independent t-test revealed no statistically significant difference in age between the ASD group and the control group, t(97) = -0.063, p = .950. A Chi-squared test revealed no statistically significant difference in educational level between the two groups, X2_{(3) = 0.992, p = .803. Besides that, a Chi-squared}

test revealed no statistically significant difference in gender between the groups, X2_{(1) =}

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Table 1

Descriptive Statistics of age, educational level, and gender in the ASD group and control group at Pretest. Group Age N M SD ASD group 50 12.96 3.23 Control group 49 13.00 3.10 Overall 99 12.98 3.15 Group Educational level

N ‘VWO’ ‘HAVO’ ‘VMBO’

ASD group 48 27 11 10 Control group 49 24 15 10 Overall 102 51 26 20 Group Gender N Boys Girls ASD group 51 42 9 Control group 51 40 11 Overall 102 82 20

Attention networks between ASD and Control group Alerting network

Multilevel data analyses showed that the explanatory variable time leads to a

significant prediction of the mean median alerting network at Posttest measurement, F(1, 83) = 5.19, p < .05, which is a small effect (d = .33; Table 2). The mean median alerting network significantly increased between Pre- and Posttest (Table 3 and Figure 4). The explanatory variable group did not lead to a significant prediction of the mean median alerting network at Pretest and Posttest, F(1, 162) = 0.02, p = .892. There are no differences between the ASD group and the control group in efficiency of the alerting network at Pretest and Posttest. Furthermore, group does not significantly contribute to the prediction of the differences in

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slopes for the mean median alerting network between Pretest and Posttest, F(1, 94) = 0.75, p = .390. (see Table 2).

Orienting network

Multilevel data analyses showed that the explanatory variable time did not lead to a significant prediction of the mean median of the orienting network at Posttest measurement, F(1, 77) = 0.17, p = .678. The explanatory variable group did not lead to a significant

prediction of the mean median orienting network at Pretest and Posttest, F(1, 179) = 0.23, p = .632. There are no differences between the ASD group and the control group in mean median of the orienting network at Pretest and Posttest. Furthermore group does not significantly contribute to the prediction of the differences in slopes for the mean median of the orienting network between Pretest and Posttest, F(1, 89) = 0.06, p = .811. (Table 2).

Executive network

Multilevel data analyses showed that the explanatory variable time lead to a

significant prediction of the mean median executive network at Posttest measurement, F(1, 100) = 7.09, p < .01, which is a small effect (d = -.47; Table 2). The mean median of the executive network decreased between Pre- and Posttest (Table 3 and Figure 4). The

explanatory variable group did not lead to a significant prediction of the mean median of the executive network at Pretest and Posttest, F(1, 161) = 0.32, p = .571. There are no differences between the ASD group and the control group in mean median of the executive network at Pretest and Posttest. Furthermore, group does not significantly contribute to the prediction of the differences in slopes for the mean median of the executive network between Pretest and Posttest, F(1, 113) = 0.35, p = .557. (see Table 2).

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Table 2

Parameter estimates of the multilevel analyses for the ASD group and control group for the alerting, orienting, and executive network before and after Mindfulness Training for children and adolescents in the ASD group.

Parameter Estimates

Bc _SE _df _t

Alerting Network

ASD groupa _-.03 _.20 _162.52 _-0.14

Posttestb _.33 _.15 _83.43 _2.28*

ASD group x Posttest .20 .23 94.81 0.86

Orienting Network

ASD group .10 .21 179.83 0.48

Posttest -.08 .19 77.35 -0.42

ASD group x Posttest -.07 .29 89.98 -0.24

Executive Network

ASD group .11 .20 161.95 0.57

Posttest -.47 .18 100.12 -2.66**

ASD group x Posttest .16 .27 113.93 0.59

a _{Results are compared to the control group.} b _{Results are compared to Pretest measurements.} c_{Can be interpreted as Cohen’s d.}

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Table 3

Descriptive statistics of the ANT measurements for the ASD group and the control group at Pretest, Posttest, and Follow-up.

Group

Alerting Network

Pretest Posttest Follow-up

N Ma SD N Ma SD N Ma SD

ASD group 40 59.81 49.71 38 86.78 56.69 36 81.65 53.76

Control group 51 59.58 45.32 51 76.86 53.18 - - -

Overall 91 59.69 47.03 89 81.09 54.61 36 81.65 53.76 Orienting Network

N Ma _SD _N _Ma _SD _N _Ma _SD

ASD group 40 30.99 40.51 38 25.46 34.32 36 17.04 30.10

Control group 51 27.25 36.59 51 24.27 36.64 - - -

Overall 91 28.89 38.19 89 24.78 35.47 36 17.04 30.10 Executive Network

N Ma _SD _N _Ma _SD _N _Ma _SD ASD group 40 68.70 53.61 38 56.39 43.14 36 55.74 33.18 Control group 51 64.60 38.38 51 44.25 36.48 - - - Overall 91 66.40 45.48 89 49.43 39.68 36 55.74 33.18 a_{Mean Median RT}

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Figure 4. Mean median alerting, orienting, and executive network of the ASD and Control group before (Pretest) and after (Posttest) 9 weeks of Mindfulness Training for the ASD group.

Attention Networks for the ASD group at Follow-Up Alerting network

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Multilevel data analyses showed that the explanatory variable time did lead to a significant prediction of the mean median of the alerting network at Follow-up compared to Pretest, F(1, 75) = 4.21, p < .05, which is a small effect (d = -.40) (Table 4). Opposite to expected, the mean median of the alerting network significantly increased between Pretest and Follow-up (Table 5; Figure 5). Time did not lead to a significant prediction of the mean median of the alerting network at Follow-up compared to Posttest, F(1, 75) = .24, p = .628 (Table 4).

Orienting network

Multilevel data analyses showed that the explanatory variable time was not a

significant, but a borderline significant predictor of the mean median of the orienting network at Follow-up compared to Pretest, F(1, 114) = 3.02, p = .085, which is a small effect (d = .39; Table 4). The borderline effect is in the direction that the mean median of the orienting network decreased at Follow-up compared to Pretest (Table 5; Figure 5). Time was not a significant predictor of the mean median orienting network at Follow-up compared to Posttest, F(1, 144) = 1.07, p = .30 (Table 4).

Executive network

Multilevel data analyses showed that the explanatory variable time was not a

significant, but a borderline significant predictor of the mean median of the executive network at Follow-up compared to Pretest, F(1, 72) = 2.78, p = .099, which is a small effect (d = .31; Table 4). The borderline effect showed a decrease in the mean median of the executive network at Follow-up compared to Pretest (Table 5; Figure 5). Time did not lead to a

significant prediction of the mean median executive network at Follow-up compared to Posttest, F(1, 72) = 0.04, p = .836. (Table 4).

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Figure 5. Mean median RT alerting, orienting, and executive network of the ASD group at Pretest, Posttest, and Follow-up.

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Table 4

Parameter estimates of the multilevel analyses for the ASD group for the alerting, orienting, and executive network at Pretest and Posttest compared to Follow-up.

Parameter Estimates Bb _SE _df _t Alerting Network Pretesta _-.40 _.19 _75.36 _-2.05* Posttesta .10 .20 75.36 .49 Orienting Network Pretesta _.39 _.23 ₁₄₄ _1.74 Posttesta _.24 _.23 ₁₄₄ _1.04 Executive Network Pretesta _.31 _.18 _72.44 _1.67 Posttesta _-.04 _.19 _72.37 _-.21

a _{Results are compared to Follow-up measurements.} b_{Can be interpreted as Cohen’s d.}

* p < .05; ** p < .01; *** p < .001

Additional Analyses

In order to investigate the exact changes in each attention network for the ASD group as well as the control group, additional multilevel data analyses were conducted to investigate the separate RT’s of the trials for each network. For each trial, a model was created with the median RT of the trial as the dependent variable, with group (ASD/control) placed at the higher level, and time (Pretest and Posttest) as the lower-level variable. Besides that, an interaction for group x time was included in the model.

The alerting network is calculated by subtracting the RT’s for double cue trials from the RT’s for no cue trials. Multilevel data analyses showed that the explanatory variable time did lead to a significant prediction of the median RT for double cue trials at Posttest

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Pre- and Posttest (Table 5). Multilevel data analyses for no cue trials did not show any significant results (Table 4). Furthermore, there are no differences between the ASD group and the control group in median RT for double cue and no cue trials at Pretest and Posttest, and group does not significantly contribute to the prediction of the differences in slopes for the median RT of double cue and no cue trials between Pretest and Posttest.

The orienting network is calculated by subtracting the RT’s for spatial cue trials from the RT’s for centre cue trials. Multilevel data analyses showed that the explanatory variable time did lead to a significant prediction of the median RT for spatial cue trials at Posttest measurement (Table 5), in the direction that the median RT for spatial cue trials significantly decreased between Pre- and Posttest (Table 6). Besides that, multilevel data analyses showed that the explanatory variable time did lead to a significant prediction of the median RT for centre cue trials at Posttest measurement (Table 5), in the direction that the median RT for centre cue trials significantly decreased between Pre- and Posttest (Table 6). The explanatory variable group did not lead to a significant prediction of the median RT for spatial cue and centre cue trials at Pretest and Posttest, and group does not significantly contribute to the prediction of the differences in slopes for the median RT of spatial cue and centre cue trials between Pretest and Posttest.

The executive network is calculated by subtracting the RT’s for congruent trials from the RT’s for incongruent trials. Multilevel data analyses showed that the explanatory variable time did lead to a significant prediction of the median RT for congruent trials at Posttest measurement (Table 5), showing a decrease in the median RT for congruent trials between Pre- and Posttest (Table 6). Besides that, multilevel data analyses showed that the explanatory variable time did lead to a significant prediction of the median RT for incongruent trials at Posttest measurement (Table 5), showing a decrease in the median RT for incongruent trials between Pre- and Posttest (Table 6). Furthermore, the explanatory variable group did not lead

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to a significant prediction of the median RT for congruent and incongruent trials at Pretest and Posttest, and group does not significantly contribute to the prediction of the differences in slopes for the median RT of congruent and incongruent trials between Pretest and Posttest.

Table 5

Parameter estimates of the multilevel analyses for the ASD group and control group for the separate RT´s per trial.

Parameter Estimates

Bc SE df t p

Double Cue Trials

ASD groupa _.18 _.20 _124.74 _0.86 _.390

Posttestb _-.35 _.09 _79.55 _-3.75 _{< .001***}

ASD group x Posttest -.04 .15 85.38 -0.28 .778

No Cue Trials

ASD group .12 .20 125.12 0.61 .542

Posttest -.15 .09 80.82 -1.60 .113

ASD group x Posttest .05 .15 86.53 0.37 .712

Spatial Cue Trials

ASD group .11 .20 122.25 0.53 .594

Posttest -.35 .09 79.47 -3.92 < .001***

ASD group x Posttest .04 .14 84.84 0.28 .781

Centre Cue Trials

ASD group .14 .20 118.49 0.70 .489

Posttest -.37 .08 80.12 -4.64 < .001***

ASD group x Posttest .00 .13 84.65 .01 .995

Congruent Trials

ASD group .13 .20 120.77 0.62 .539

Posttest -.26 .08 80.63 -3.10 < .01**

Incongruent Trials

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Posttest -.40 .09 79.95 -4.66 < .001***

a _{Results are compared to the control group.} b _{Results are compared to Pretest measurements.} c_{Can be interpreted as Cohen’s d.}

* p < .05; ** p < .01; *** p < .001

Table 6

Descriptive statistics of the RT’s per trial for the ASD group and the control group

Group

Double Cue Trials

N M SD N M SD N M SD

ASD group 40 582.39 90.31 38 549.67 118.27 36 524.08 79.72 Control group 51 571.83 101.44 51 536.83 89.77 - - - Overall 91 576.47 96.32 89 542.31 102.48 36 524.08 79.72

No Cue Trials

Spatial Cue Trials

Centre Cue Trials

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Conclusion and Discussion

In this study we investigated whether children and adolescents with and without ASD show differences in attention networks (alerting, orienting, executive control) as measured with the Attention Network Task (ANT). Besides that, it was investigated if these differences disappear after children and adolescents with ASD receive 9 weeks of Mindfulness Training. Furthermore, it was investigated if the effects of Mindfulness Training for children and adolescents with ASD remain after a 9 week Follow-up period. Main findings indicate that there are no differences between children and adolescents with and without ASD at Pre- and Posttest, and thus that there is no effect of 9 weeks Mindfulness Training at Posttest and Follow-up, as compared to the effect of time and repeated measurement in TD children and adolescents who did not receive mindfulness training.

Alerting Network and Mindfulness Training

In line with expectations, children and adolescents with and without ASD did not show any differences in the alerting network at Pretest and Posttest. Unexpectedly, both the ASD group and the control group showed a less efficient network at Posttest measurement

Congruent Trials

Incongruent Trials

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compared to Pretest measurement. This was expressed in a significant increased alerting network at Posttest compared to Pretest. Furthermore, when evaluating the ASD group at Follow-up, there was no additional effect on the efficiency of the alerting network.

To provide an explanation for the decrease of efficiency in the alerting network, we looked at the separate trials for the alerting network. This network is calculated by subtracting the RT’s for double cue trials from the RT’s for no cue trials. The double cue trials are less difficult compared to no cue trials, because two asterisks are presented before the target fish appears, while in no cue trials the fish will appear without any warning. Additional multilevel analyses showed that in the ASD and the control group, the RT’s for both trials decreased over time. However, in both groups the RT’s for double cue trials decreased relatively more compared to no cue trials, and this decrease was significant. This caused a larger difference between the two trials, and thus a less efficient alerting network. This shows that both children and adolescents in the ASD group as well as in the control group performed significantly better on the more simple trial at Posttest. Because RT’s on double cue trials significantly decreased for the control group as well as the ASD group, we cannot conclude that the improvement on double cue trials is due to Mindfulness Training. Perhaps children and adolescents in both groups remembered that the target fish appeared after the presentation of the two asterisks, and stayed more alert when they got warned by the double cue, indicating a learning effect of the ANT. Children and adolescents in de ASD group did not further improve their RT on double cue trials at Follow-up compared to Posttest.

Orienting Network and Mindfulness Training

For the orienting network, we hypothesized that children and adolescents with ASD show a less efficient orienting network compared to children and adolescents in the control group, and that children and adolescents with ASD improve their efficiency of the orienting network after 9 weeks of Mindfulness Training. Opposite to the hypothesis, children and

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adolescents with and without ASD did not show any differences in the orienting network at Pretest as well as at Posttest measurement. At Follow-up, children and adolescents with ASD showed a borderline significant improvement of the efficiency of the orienting network compared to Pretest. When we take the separate RT’s of the trials for the orienting network into account, the center cue trial and spatial cue trial, the ASD and the control group both showed significant decreases in RT over time. Children and adolescents with and without ASD improved their RT on spatial and center cue trials at Posttest, which might indicate a learning effect of the ANT. There was no additional effect on the separate trials at Follow-up compared to Pretest for children and adolescents in the ASD group.

Executive Network and Mindfulness Training

Opposite to the hypothesis that children and adolescents with ASD show a less efficient executive network compared to children and adolescents in the control group, there were no differences in the executive network between the ASD group and the control group at Pretest and at Posttest. However, children and adolescents with ASD showed a more efficient executive network as expressed in a significant decreased RT at Posttest compared to Pretest. Since this decrease was also found in the control group, we cannot conclude that Mindfulness Training contributes to a more efficient executive network. When comparing the separate RT’s of the trials for the executive network, the congruent trial and incongruent trial, the ASD and the control group both show significant decreases in RT over time. Children and

adolescents with and without ASD react more quick on congruent and incongruent trials at Posttest. Perhaps children and adolescents in the ASD group and the control group

remembered the trials for the executive network and were less distracted by the congruent and incongruent stimuli at Posttest, indicating a learning effect. A learning effect for the executive network was also found in a study investigating the effects of repeated measurement of the ANT in a sample of young healthy adults, indicating participants learned how to ignore

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irrelevant distractors (Ishigami & Klein, 2010). However, this study consisted of only 10 participants, and the ANT was performed 10 times with approximate 8 days in between. Limitations, Strengths and Future Research Recommendations

Research on attention networks as measured with the ANT suggests that there are differences in the orienting network and/or executive network in children and adults with ASD compared to children and adults without ASD. One study found a less efficient orienting and executive network in children with ASD compared to TD children (Mutreja et al., 2016), and other research suggest children with ASD show only a less efficient orienting network in comparison to TD children (Keehn et al., 2010). Besides that, when comparing adults with ASD and healthy adults, adults with ASD show a less efficient executive network (Fan et al., 2012). Contradictory to the these results, we did not find any differences in the orienting and executive attention networks between the ASD group and the control group. Besides

differences in attention networks, research suggest that Mindfulness Training might enhance different aspects of attention (Shapiro et al., 2006). In a study where attention networks as measured with the ANT were compared in healthy adults that meditate and do not meditate, the adults that meditate show a significant more efficient orienting and executive network than adults that do not meditate (Van de Hurk et al., 2010). Other research did find a more efficient orienting network in participants that received 8 days of Mindfulness Training (Jha et al., 2007). Opposite to these results, we did not find any effects of Mindfulness Training on one of the three networks in children and adolescents with ASD.

Several limitations of the study must be taken into account considering these results. First of all, children and adolescents in the control group were not assessed on behavior or developmental problems. Children and adolescents in the control group only answered the question whether they were diagnosed with a developmental disorder. It is possible that the control group consisted of some children and adolescents meeting criteria for a diagnosis and

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simply were never tested. Future research might control for this possibility by including extra questionnaires for participants in the control group before including them in the study, such as the Behavior Rating Inventory of Executive Function (BRIEF) or the Youth Self Report (YSR).

A second limitation is the low reliability of the ANT. Research suggests the ANT has low reliability due to inequivalence of psychometric properties across the three networks (MacLeod et al., 2010). This inequivalence might have influenced the observed effects in this study. It is of importance that future research replicates the current study with additional attention measures, such as the subscale attention problems of the Child Behavior Checklist (CBCL) as reported by parents and the Youth Self Report (YSR). For example, in a recent study where forty-five children and adolescents aged 8 until 19 years old and one of their parents received 9 weeks of Mindfulness Training, attention problems were assessed with help of questionnaires (Ridderinkhof, de Bruin, Blom, & Bögels, 2017). Parents filled in the subscale attention problems of the CBCL and children of 11 years and older completed the subscale attention problems of the YSR. Results show that parents reported a significant improvement of attention at Posttest and two months after the last session of Mindfulness Training, which was a small effect. At 1-year Follow-up, a medium effect was found. At Posttest, there was no reduce in attention problems as reported by children on the YSR. However, two months after the last session of Mindfulness Training and at 1-year Follow-up, attention problems reduces with a medium effect size as reported by children on the YSR.

Furthermore, children and adolescents with ASD performed the ANT in a stimulus free room, without any distractors so that the children and adolescents were not

overstimulated or aroused. There was only one researcher present in the room, who gave a very clear and concise explanation of the task that the children and adolescents had to

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the environment compared to TD children and adolescents, it might be possible that children and adolescents with ASD perform differently on the ANT when they are surrounded by distractors in the environment, which also occur in daily life. Future research might

investigate the differences in attention networks between children and adolescents with and without ASD as measured with the ANT in an environment with for example controlled distractors, such as noise, changing light, or people moving around.

Another suggestion for future research is to include more girls in the study. In the general population of ASD, there is a male-female ratio of 4:1, thus the male-female ratio in our sample reflects the population (Schaafsma & Pfaff, 2014). However, it might be possible that other results will be found when the male-female ratio is more equal. There is one study that investigated gender differences in ASD symptoms among children and adolescents between 5 and 20 years old with ASD (Holtmann, Bölte, Poustka, 2007). All children and adolescents filled in the attention subscale of the CBCL. Results indicate that girls showed significantly more attention problems compared to boys (Holtmann, Bölte, & Poustka, 2007). Since we had more boys in our sample compared to girls, this could have influenced the results. It is possible that when we include more girls, differences between the ASD group and the control group will be found, since it might be that girls with ASD show more attention problems compared to boys with ASD. It is of importance that future research on attention in children and adolescents with ASD includes more girls to investigate gender differences in the manifestation of an atypical attention.

Unexpectedly, we did not find any differences in attention networks between children and adolescents with and without ASD. Therefore, it should be noted that it was not necessary for the children and adolescents in the ASD group to improve their efficiency of one of the attention networks through Mindfulness Training. Since children and adolescents with ASD performed as good on the ANT as children and adolescents without ASD, Mindfulness

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Training did not have an effect on the ANT scores in the ASD group. While abovementioned limitations might be an explanation for these unexpected results, future research should take into consideration that atypical attention in children and adolescents with ASD might manifest in other attentional processes than measured with the ANT. Therefore, more research in this area is needed.

Besides limitations, the study has some strengths. To our knowledge, it is the first study that compares attention networks in children and adolescents with and without ASD as measured with the ANT at two timepoints. Secondly, it is the first study that evaluates the effect of Mindfulness Training on attention networks in children and adolescents with ASD as measured with the ANT using a control group. Therefore, the design of the study makes it possible to control for the possibility of a learning effect. Besides that, the ASD group and the control group did not show any differences in age, gender and educational level, and thus were matched correctly. Furthermore, the additional analyses on the separate trials for each attention network made it possible to give more insight in the process of change of the efficiency of each network.

Although we did not find significant improvements of the orienting network at

Posttest and Follow-up, and for the executive network only an improvement at Posttest, other research suggest that the effect of Mindfulness Training on attention develops over time (Semple et al., 2010). It might be that when the effect of Mindfulness Training is assessed at a 1 year Follow-up, other patterns will be found. Besides that, while we only measured the attention networks with the ANT, it might be of particular interest to involve neuroimaging techniques to further assess the different processes underlying the attention networks in children and adolescents with ASD. Although we did not find any differences between children and adolescents with and without ASD, it might be possible that these techniques

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reveal an explanation for the manifestation of atypical attention in children and adolescents with ASD.

Summary

While this study indicates that there are no differences in attention networks between children and adolescents with and without ASD, and that Mindfulness Training does not enhance the efficiency of attention networks as measured with the ANT, the findings of our study contribute to the current knowledge of attention networks and Mindfulness Training in children and adolescents with ASD. Our study emphasizes the importance of future research investigating the effect of Mindfulness Training on attention as measured with other attention measures, for example the subscales of attention of the CBCL and the YSR. Since our study indicates there might be a learning effect of the ANT, more research is needed to evaluate the effect of Mindfulness Training on attention. Future research might investigate the reliability of the ANT in a repeated-measurement design, with several weeks between measurements. Furthermore, a recent study indicates that Mindfulness Training is effective in improving attention in children and adolescents as measured with the subscale attention problems of the CBCL and the YSR (Ridderinkhof et al., 2017). Results of this study show that parents

reported a significant reduction of attention problems in children and adolescents with ASD at Posttest and 2-month Follow-up which was a small effect, and a medium effect at 1-year Follow-up. Children did report a significant reduction of attention problems at a 2-month and 1-year follow up (Ridderinkhof et al., 2017). It is therefore essential that future research continues to investigate how mindfulness-based interventions can be most beneficial for children and adolescents with ASD in reducing attention problems.

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