Children assessed for Autism Spectrum Disorder: Developmental delay and change over time in BDI-2 developmental quotients

Research in Autism Spectrum Disorders 8 (2014) 1500–1507

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Children assessed for Autism Spectrum Disorder: Developmental delay and change over time in BDI-2 developmental quotients Lindsey W. Williams *, Johnny L. Matson, Rachel L. Goldin, Hilary L. Adams Louisiana State University, United States

A R T I C L E I N F O

A B S T R A C T

Article history: Received 24 March 2014 Received in revised form 28 July 2014 Accepted 4 August 2014

Individuals with Autism Spectrum Disorder (ASD) often have overall developmental delays and delays in developmental domains outside of the core ASD symptoms. Research results have been mixed regarding the stability of level of functioning over time in young children with ASD symptoms. Elements that influence development over time in young children with ASD symptoms are an important area of research. Early assessment and intervention is critical to improving prognosis, though effectiveness of intervention depends on a number of factors with some researchers suggesting IQ or overall functioning may influence the degree or rapidity of treatment effects. Using the Battelle Developmental Inventory, this study investigates the effect of overall developmental quotient (DQ) at first assessment on subsequent DQ scores, including scores in communication and adaptive domains in a sample of toddlers evincing significant ASD symptoms. ß 2014 Elsevier Ltd. All rights reserved.

Keywords: Autism Spectrum Disorder Developmental change Developmental quotient BDI-2

The developmental trajectory of infants and toddlers with Autism Spectrum Disorder (ASD) is heterogeneous, as individuals with ASD vary tremendously in symptom presentation and symptom severity (Ben-Itzchak & Zachor, 2007; Corsello, 2005; Fenske, Zalenski, Krantz, & McClannahan, 1985; Fodstad, Matson, Hess, & Neal, 2009; Horovitz & Matson, 2010; Matson, 2007). In addition to the core features of ASD, which include impairments in communication and socialization, and presentation of repetitive and restricted behaviors, individuals with ASD generally experience delays in overall development and across a number of developmental domains (Kozlowski, Matson, Horovitz, Worley, & Neal, 2011; Matson, Kozlowski, Hattier, Horovitz, & Sipes, 2012; Matson & Rivet, 2008; Matson & Wilkins, 2009; Smith & Matson, 2010; Worley & Matson, 2012). Additionally, comorbid psychopathology and challenging behaviors also commonly co-occur with ASD (LoVullo & Matson, 2009; Matson, Hess, & Boisjoli, 2010; Matson, Mahan, Hess, Fodstad, & Neal, 2010). Furthermore, multiple physical and adaptive problems are commonly observed (Matson, Dempsey, & Fodstad, 2009a; Matson, Dempsey, & Fodstad, 2009b; Matson, Rivet, Fodstad, Dempsey, & Boisjoli, 2009). As a result of the wide diversity in manifestation of the disorder, designing and implementing treatment for ASD has to be done on an individual basis. Early identification and intervention is crucial in improving prognosis (Kozlowski, Matson, & Worley, 2012; Sipes, Matson, Worley, & Kozlowski, 2011; Virues-Ortega, Rodriguez, & Yu, 2013; Zwaigenbaum, Bryson, & Garon, 2013). Researchers have found that if appropriate interventions are identified and applied early, outcomes for individuals with ASD

* Corresponding author at: Department of Psychology, Louisiana State University, Baton Rouge, LA 70803, United States. Tel.: +1 8039248089. E-mail addresses: [email protected], [email protected] (L.W. Williams). http://dx.doi.org/10.1016/j.rasd.2014.08.001 1750-9467/ß 2014 Elsevier Ltd. All rights reserved.

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are significantly improved (Matson, Mahan, & Matson, 2009; Matson, Tureck, Turygin, Beighley, & Rieske, 2012). However, some early intervention programs have been found to be more beneficial than others (Baghdadli et al., 2007; Eldevik, Eikeseth, Jahr, & Smith, 2006; Gabriels, Hill, Pierce, Rogers, & Wehner, 2001; Jo´nsdo´ttir, Saemundsen, Antonsdo´ttir, ´ lason, 2011; Sallows & Graupner, 1999; Smith, Eikeseth, Levstrand, & Lovaas, 1997). Personal Sigurdardo´ttir, & O characteristics also play a role in prognosis. Factors which contribute to the effectiveness of treatment include age, time of symptom onset, intelligence quotient (IQ), and functioning level (Perry et al., 2008; Perry, Blacklock, & Dunn Geier, 2013). Tests that evaluate IQ typically emphasize verbal, conceptual, and problem-solving skills, which involve multiple cognitive processes including attention, working memory, and processing speed (Berk, 2007; Siegal, 1989). It is difficult to evaluate cognitive functioning in young children by using tests that yield IQ, and results are generally considered unstable (Fombonne, 1999). In addition to the difficulties related to attention or compliance in young children for the types of tasks typical to IQ tests, it is difficult to measure complex cognitive processes in infants and toddlers who are still developing the basic building blocks of these skills. The development of cognitive functioning in later childhood is affected by prior development in multiple domains during early childhood; for example, language development is important for the development of reasoning skills, emotional regulation, and memory, which impact future learning and cognitive development (Berk, 2007). An attempt to measure intelligence in an infant would be primarily a measure of sensorimotor performance, which is not the principle focus of later intelligence testing (Neisworth & Bagnato, 1992). Observable infant perceptual and motor tasks which indicate development along the usual trajectory differ from those tasks given to older children and do not necessarily tap the same aspects of intelligence measured at older ages. Tests which measure observable perceptual, motor, social, and other behaviors indicative of developmental growth in young children yield scores called developmental quotient (DQ) rather than IQ (Berk, 2007). Developmental quotient is a number that, like IQ, indicates where a child’s development lies on a continuum compared to other children his or her age across domains which together contribute to overall developmental growth (Berk, 2007; Newborg, 2005). DQ is assessed by investigating presence or absence of behaviors indicative of developmental growth across a number of developmental domains, such as motor, language, self-care, adaptive, and social skills (Newborg, 2005). DQ therefore serves as a better indicator of overall level of functioning in young children. Early childhood is considered a time of significant developmental growth (American Psychological Association Task Force on Evidence-Based Practices for Young Children & Adolescents, 2008). However, research results have been mixed regarding the stability of level of cognitive and adaptive functioning over time in both typically developing children and young children with ASD symptoms, with variability seemingly impacted by a number of factors including environmental changes or family stressors, low socioeconomic status, or comorbid disability (Berk, 2007; Breslau et al., 2001) as well as the effects of various interventions (Baghdadli et al., 2007). Adverse environmental conditions or lack of opportunity to practice new skills can hinder developmental progress, whereas high-quality caregiving or intensive intervention can have a positive effect on social, language, motor, and cognitive development (Burchinal et al., 2000; Campbell, Pungello, Miller-Johnson, Burchinal, & Ramey, 2001; Nelson et al., 2007). Some studies comparing estimates of cognitive functioning obtained from measures providing DQ scores with those obtained from standardized intelligence tests at a later date have indicated DQ measures provide a reasonable estimate of future functioning in typically developing young children (Albers & Grieve, 2007), and in young children with ASD (Delmolino, 2006; Kurita, Osada, Shimizu, & Tachimori, 2003). Lord and Schopler (1989) found that IQ and DQ scores showed little overall change in young, language-impaired children with and without ASD, with no significant differences in group means, absolute difference scores, or patterns of change across developmental domains. While significant heterogeneity exists within individuals, some researchers have found relative stability of DQ scores in young, atypically developing children and young children with ASD when studied as a group (Baghdadli et al., 2007; Lord & Schopler, 1989). It is important to note, however, that these results may have been affected by the fact that DQ/IQ scores tend to remain more stable for children with severe disabilities who are likely to continue to exhibit deficits and a slower rate of developmental progress compared to typically developing children, whose development across domains may be more variable with periods of rapid development along an overall ‘‘normal’’ trajectory (Bagnato & Neisworth, 1994; Maisto & German, 1986). Other researchers have found infant and toddler DQ to be a poor predictor of future IQ scores in low birth weight children who initially scored poorly on developmental assessments (Hack et al., 2005), and intensive intervention can contribute to significant change in developmental scores over time (Reed, Osborne, & Corness, 2007; Sallows & Graupner, 1999). In older children and adults, it is estimated that up to 70% of individuals with ASD also have intellectual disability (ID) (Isaksen, Diseth, Schsølberg, & Shjeldal, 2013; Mandell et al., 2012; Matson & Kozlowski, 2011). Comorbid ID has been found to predict a poorer prognosis for those with ASD (Baird et al., 2006; Klin et al., 2007; Rojahn et al., 2009), whereas speech and overall intellectual functioning predict more positive outcomes in children with ASD (Darrou et al., 2010). However, the prognostic contribution of measuring developmental deficits in children too young for IQ assessment is unclear. Baghdadli et al. (2007) found significant variability in the developmental trajectory of young children with autism, with some improving rapidly with treatment, while others experienced slower growth and less improvement over time. Maisto and German (1986) found moderate correlations over time in cognitive and motor DQ scores on the Bayley Scale of Infant Development, but considerably variable scores for other domains. Conversely, Moyal (2010) found moderate correlations of Total DQ scores across time in children with developmental delays, but weak correlations for Cognitive DQ scores and an inconsistent relationship between overall DQ change and length of time receiving special education services. In a study of preschool aged children with ASD placed in a special day program for 10 months, Reed, Osborne, and Corness (2007) found

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small but statistically significant gains on measures of adaptive behavior and greater gains in cognitive skills. Other researchers have found no improvement in standardized measures of developmental functioning in young children receiving community or school-based intervention programs (Baghdadli et al., 2007; Magiati, Charman, & Howlin, 2007; Salt et al., 2002). Type of intervention likely plays a significant role in developmental progress; Sallows and Graupner (1999) found a decrease in developmental scores over a 3 year period in toddlers with ASD who received a combination of school and home based therapies, but significant increases in adaptive and cognitive scores for toddlers receiving at least 13 h per week of intensive behavioral-based therapy. Some researchers have suggested that developmental quotient (DQ) may serve as a useful factor in identifying young children with ASD who will benefit most rapidly from early intervention, with those showing higher overall initial scores experiencing the greatest degree of improvement in developmental scores following intervention (Kuroda & Kato, 1995; Ogiwara & Takahashi, 2005; Ortega, Garcia, & Yu, 2013; Virues-Ortega, Rodriguez, & Yu, 2013). In a study of 57 2-year old children with ASD, Takeda, Koyama, Kani, and Kurita (2005) found that a Cognitive/Adaptation DQ score 70 on the Kyoto Scale of Psychological Development at 2 years was fairly predictive of slower developmental progress and IQ 70 at age 5, and that the Cognitive/Adaptation domain score was particularly stable for children with DQ <50. Conversely, 2 year olds with DQ >70 showed more dramatic increases in abilities and later IQ score (Takeda et al., 2005). Improvement in communication skills may be an important factor for development in other developmental domains. In a study of children with Downs syndrome and children with ASD over a one year period, Kuroda and Kato (1995) found that children with ASD were more likely to exhibit improved overall DQ scores, with the most dramatic overall increases seen in those who improved the most in communication. In a study that used IQ rather than DQ scores, Szatmari et al. (2000) also noted that improvement in communication skills correlated with greater overall improvements in scores. In a two-year study of children with ASD ages 4–6 years, though IQ scores for most children remained stable, those who made significant gains in overall IQ scores were those who gained oral fluency between first and second administration (Szatmari et al., 2000). Others have found little difference in overall IQ or DQ scores over time in children with communication impairment with or without ASD, though individual exceptions exist (Baghdadli et al., 2007; Lord & Schopler, 1989; Szatmari et al., 2000). In addition to finding little overall improvement in young children with ASD as a group, Baghdadli et al. (2007) also found a trend toward regression in adaptive skills, due to a slower rate of development compared to advancing chronological age. The purpose of the current study was to investigate developmental growth of infants and toddlers with significant ASD symptoms over time. Overall development as measured by the Total DQ score of the Battelle Developmental Inventory, 2nd edition (BDI-2; Newborg, 2005) was of interest; this score takes into account development in adaptive, cognitive, communication, motor, and personal–social skills. Each area of infant/toddler development is interrelated with and has an effect on development in other domains (Berk, 2007), hence our intent to investigate overall development. Further, the authors examined the improvement in two specific domains, communication and adaptive skills. These areas were chosen because these are areas in which children with ASD often exhibit deficits, and these domains are also frequent targets of service provision in this participant sample. Changes in scores over time were analyzed to see if those with an initially low DQ score (i.e., 70 or less) improved more, less or at the same rate as those with an initially average or above average DQ. Due to some studies indicating greater gains in DQ/IQ scores for children who had higher initial DQ scores (e.g., Kuroda & Kato, 1995; Ogiwara & Takahashi, 2005; Takeda et al., 2005; Virues-Ortega, Rodriguez, & Yu, 2013), it was hypothesized that infants and toddlers with ASD symptoms who initially exhibited low Total DQ (70) scores would show less improvement overall and in communication and adaptive domains compared to those with an initial Total DQ >70. 1. Method 1.1. Participants The initial data sample included 211 participants from a larger pre-existing database of children referred for service evaluation by the EarlySteps program. Many individuals receive an initial assessment and are then lost to follow-up or deemed ineligible for EarlySteps services, thus do not receive multiple full EarlySteps evaluations including the data required for this study. The sample of 211 consisted of children age 36 months and younger and who received multiple administrations of the BDI-2. One hundred twenty one participants were removed from further analysis due to missing data (e.g., age at time of assessment), administration of the BISCUIT-Part 1 to children below the minimum age cited in the manual, minimal to no ASD symptoms, fewer than 12 months between assessment administrations, or no initial BDI-2 score equal to or below 70. The sample used in this study included only individuals with at least 12 months between administrations of the BDI-2 (Newborg, 2005), because a time period of at least 12 months between administrations was required as a shorter time period is unlikely to show significant change in development, even in toddlers (Maisto & German, 1986). Additionally, to be included, individuals must have had scores on the Baby and Infant Screen for Children with Autism, Part 1 – Diagnostic (BISCUIT Part 1; Matson, Boisjoli, & Wilkins, 2007) that reached or surpassed an established cut off of >17 (Matson et al., 2009e), which in practice EarlySteps uses as an indication that the child is ‘‘at-risk’’ for ASD and further evaluation is recommended. Next, participants needed at least one BDI-2 Adaptive or Communication subdomain standard score 70 at the first administration. This criterion insured that the participants qualified for intervention and continued follow-up provided by EarlySteps in these areas. All the participants were recipients of services from EarlySteps; EarlySteps is

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Table 1 Demographics by DQ group.

Months: mean (SD) Age at 1st assessment Between assessments Gender (%) Males Females Race (%) Caucasian African American Hispanic Other/unspecified a

Low DQa (n = 50)

Average DQ (n = 40)

19.62 (1.50) 12.70 (1.16)

19.35 (1.46) 12.72 (1.41)

70.00 30.00

70.00 30.00

40.00 48.00 2.00 10.00

60.00 32.00 2.50 5.00

Participants in Low DQ group had BDI-2 Total DQ scores 70.

Louisiana’s Early Intervention System under the Individuals with Disabilities Education Act, Part C, which provides services to infants and toddler from birth to 36 months of age. Children qualify for EarlySteps services if they have a significant developmental delay in at least one developmental domain or a diagnosed medical condition commonly associated with developmental problems (e.g., cerebral palsy, epilepsy, deafness, blindness, tubular sclerosis, premature birth). In this sample, comorbid diagnoses included seizures, premature birth, neurofibromatosis, hydrocephaly, Fragile X syndrome, Down syndrome, cerebral palsy, hearing loss, cerebellar hypoplasia, global developmental delay, and asthma. These participants were included in this study, as a comorbid diagnosis does not preclude ASD symptoms or diagnosis. A total of 90 participants, ages 17–23 months (M = 19.5, SD = 1.48), met all inclusion criteria and were included in the present study. Of the 90 participants, 70.0% were male and 30.0% were female. The sample was 60.0% Caucasian, 32.5% African American, 2.5% Hispanic, and 5% Other/Unidentified. These participants were further separated based on their Total DQ scores, which is derived from scores on all domains in the BDI-2 (i.e., adaptive, cognitive, communication, motor, and personal–social). The Low DQ group (n = 50) was composed of any individual who had a Total DQ less than or equal to 70, whereas the Average DQ group (n = 40) had a Total DQ greater than 70 but had at least one of the targeted domain scores (i.e., Adaptive, Communication domains) less than 70, as per the first criterion. Overall, 85 (94%) of participants had an initial delay in Communication, and 75 (83.33%) had a delay in the Adaptive domain. Fifty-five participants (61.11%) had delays in both Communication and Adaptive domains. Demographics for the groups of participants included in the present study are presented in Table 1. 1.2. Measures 1.2.1. Battelle Developmental Inventory, second edition (BDI-2; Newborg, 2005) The BDI-2 aims to assess the development of children from birth to 7 years, 11 months of age in the following skill areas: adaptive, cognitive, communication, motor, and personal–social (Newborg, 2005). The BDI-2 has several administration options: a structured, play-based activity using a kit of manipulatives; an observation conducted in the child’s natural setting (e.g., home, daycare); and a scripted interview with a parent, teacher, or caregiver. Based on observation or informant report, administrators of the measure rate the quality of aspects of the child’s development from zero to two for a total of 450 items. A rating of zero corresponds to no ability, one corresponds to emerging ability, and two corresponds to ability present. Ratings are used to determine scores for each domain, as well as an overall Total Developmental Quotient (DQ). The domain scores and DQ each have a mean of 100, standard deviation of 15, and range of 40 to 160, as well as corresponding percentile ranks and confidence intervals. The BDI-2 appears to have robust psychometric properties. Test–retest reliability was determined to be above .80 for the total score and all domain scores, while internal consistency coefficients ranged from .98 to .99 (Newborg, 2005). 1.3. Procedure 1.3.1. Testers and test administration Prior to initiation of screening protocol, approval was obtained from the Louisiana State University Institutional Review Board and the State of Louisiana’s Office for Citizens with Developmental Disabilities (OCDD). Additionally, parents and legal guardians of participants provided informed consent prior to administration. Standard screening protocol included parent interviews and child observations conducted in the child’s home or daycare. All administrators of the screening protocol for Louisiana’s EarlySteps program are required to have an appropriate degree and certification or licensure. Each of the approximately 175 professionals whom conducted the assessments were licensed or certified in various applicable fields (e.g., occupational therapy, physical therapy, psychology, special education, social work, speech-language pathology) and had various degrees (e.g., bachelor’s degree in early childhood education,

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doctoral degree in psychology). Additionally, all assessors were familiar with evaluation of and treatment for young children, as well as had been through training about, and had experience in administering, the included measures. 1.4. Statistical analyses All analyses were conducted using SPSS 22.0 with the exception of effect sizes, which were calculated by hand. Differences in sex and ethnicity were analyzed using Chi-square. Group differences were not significant for sex, x2 (1) = .00, p = 1.0, or for ethnicity, x2 (3) = 3.86, p = .277. Potential differences in age at first administration or months between administration were analyzed within the Analysis of Variance (ANOVA) for entire sample, with no statistically significant differences for age at first administration, F(1,84) = .145, p = .704, or for months between administrations, F(1,84) = 1.10, p = .298, thus indicating homogeneity of regression slopes was maintained. A t-test was conducted to examine changes in Total DQ scores between groups. Follow-up tests all employed Bonferroni corrections. The initial analysis was followed by ttests to examine DQ change across individual domains (i.e., Communication and Adaptive). The first set of follow up t-tests was employed to look at change in Communication and Adaptive domains including all participants, regardless of whether they scored 70 in either domain at the initial assessment. This was followed by analysis that excluded participants who did not exhibit initial delays. Children who did not have a delay in these domains (Communication, n = 11; Adaptive, n = 21) were excluded from this analysis because it is unlikely that without an initial delay they would have received EarlySteps intervention specific to these areas between administrations, and we were interested to note degree of change in children most likely to have received intervention between BDI-2 administrations. Finally, repeated measures t-tests were conducted to examine domain change over time within groups for those individuals initially exhibiting a deficit in Communication and/ or Adaptive domains. 2. Results Outcomes of the t-test yielded a statistically significant difference in change between Total DQ scores in the Low DQ and Average DQ groups, t(88) = 3.31, p = .001, and represented a medium effect size, d = .70. On average, participants in the Low DQ group experienced a greater degree of change in Total DQ (M = 6.46, SE = 1.48) than did participants in the Average DQ group (M = 1.07, SE = 1.75). Levene’s test indicated homogeneity of variance was maintained (p = .591) (Table 2). The significant results in the step above were followed up with comparisons of the Communication and Adaptive domain scores. Two sets of analyses were conducted via t-tests with Bonferroni corrections applied; the first analysis included all participants regardless of initial DQ score in the respective domains, and the second analysis excluded those who did not have initial delays in the respective domains. Overall, both Low DQ (M = 9.78, SE = 1.94) and Average DQ (M = 8.64, SE = 2.34) groups revealed improved Communication scores. The difference between groups was insignificant, t(88) = .37, p = .707, d = .10). Similarly, no significant difference between the Low DQ (M = 10.54, SE = 1.97) and Average DQ (M = 4.65, SE = 2.45)

Table 2 Change in GPA for male and female BDI-2 scores* at first and second administration. Domain

n

1st administration Mean

Total DQ Low DQ Average DQ Communication Low DQ Average DQ Adaptive Low DQ Average DQ Communicationa Low DQ Average DQ Adaptivea Low DQ Average DQ Communicationb Low DQ Average DQ Adaptiveb Low DQ Average DQ

SD

2nd administration Mean

b

Change Mean

SD

50 40

60.84 80.70

6.75 6.04

68.08 78.43

9.09 9.27

6.46 1.07

10.48 11.06

50 40

57.14 67.32

3.43 10.61

67.27 75.82

14.64 15.90

10.12 8.64

13.64 14.64

50 40

63.92 78.50

9.21 15.28

74.46 83.15

13.20 12.00

10.54 4.65

13.95 15.52

50 29

57.14 61.57

3.43 5.58

67.27 72.54

14.64 14.53

10.12 10.96

13.64 14.20

41 18

60.51 65.00

5.34 7.79

73.41 81.28

13.19 11.30

12.90 16.28

12.09 11.30

0 11

– 80.75

– 6.46

– 84.18

– 16.83

– 2.72

– 14.72

9 22

79.44 89.55

6.82 11.11

79.22 84.68

12.91 12.59

.22 4.86

17.36 11.30

* SD for the BDI-2 = 15. Analysis included only participants with initial Low DQ (70) in this domain. Analysis included only participants who did not have initial Low DQ in this domain.

a

SD

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groups was seen for Adaptive DQ scores, t(88) = 1.89, p = .062, d = .40. Next, t-tests with Bonferroni correction were used to inspect change specific to those children who exhibited delays in the Communication or Adaptive domains at first administration. Of those both Low DQ (M = 10.12, SE = 1.95) and Average DQ groups (M = 10.96, SE = 2.68) improved on Communication DQ scores. No significant difference was found between groups with regard to change in Communication DQ scores, t(77) = .26, p = .798, d = .06. Similarly, both Low DQ and Average DQ groups improved on scores of Adaptive DQ over time (M = 12.90, SE = 1.88 and M = 16.27, SE = 2.7, respectively), and no statistically significant difference was found between groups with regard to change in Adaptive DQ scores, t(57) = .99, p = .322, d = .28. Finally, analysis of change within groups over time for those children exhibiting initial domain delays by using repeated measures t-test revealed Adaptive scores for participants exhibiting an initial delay showed statistically significant change for both the Low DQ group, t(40) = 6.831, p < 001, d = 1.28, and for the Average DQ group, t(17) = 5.95, p < .001, d = 1.67. Similarly, statistically significant change was noted for Communication in both the Low DQ group, t(49) = 5.19, p < .001, d = .95, and the Average DQ group, t(28) = 4.09, p < .001, d = .99. Of note, with the exception of Adaptive scores in the Average DQ group, these changes represented less than one standard deviation on the BDI-2 (which has a standard deviation of 15 points); however, these changes did represent a large effect size. 3. Discussion Among the many topics in the field of ASD, developmental trajectories are one of the most important (Matson & LoVullo, 2009). In this sample, contrary to the initial hypothesis, the participants in the Low DQ group showed statistically significant greater improvement in overall Total DQ, with an average improvement of 6.46 points, while the scores of those in the Average DQ group essentially remained unchanged. It could be that some of the children who initially showed low scores exhibited regression toward the mean upon subsequent testing; it is also possible that those children who were perceived to have greater deficits at the outset were considered to be in greater need of service provision and thus received more intensive and/or a wider variety of interventions than children in the Average DQ group which positively affected overall development. The variability in scores for both the Low DQ and Average DQ groups suggests some individuals improved very much, while others did not improve or even exhibited a decrease in scores. Large standard deviations indicate a wide variation in development among individuals in both groups, in line with research showing that toddlers with ASD reach major developmental milestones at different rates (Matson, Mahan, Fodstad, Hess, & Neal, 2010). Furthermore, it is possible that some children in the sample, particularly those in the Average group at first assessment, experienced regression of skills between the first assessment (mean age approximately 19 months) and the second assessment. Prevalence rates of regression for children with ASD have been estimated to be between 20% and 50%, with estimates of mean age generally ranging from 12 to 24 months of age (Barger, Campbell, & McDonough, 2013; Bernabei, Cerquiglini, Cortesi, & D’Ardia, 2007). Contrary to hypothesized patterns, no significant differences were found between mean change scores in the Communication or Adaptive domains between Low DQ and High DQ for those participants exhibiting a deficit at first assessment; while the Average DQ did improve more than the Low DQ group, this difference was insignificant. Within groups, Low DQ and Average DQ groups showed notable improvement in these domains, with large effect sizes and mean scores improving half a standard deviation or more. It is noteworthy, however, that with the exception of the Adaptive domain for the Average DQ group, overall group gains were less than one standard deviation of the BDI-2. Again, wide standard deviations indicated significant variability among individuals with regard to development in these domains. Some children experiencing regression of skills could impact variability in scores and contribute to the high standard deviation of scores in the Adaptive and Communication domains. Furthermore, the actual initial differences in initial DQ scores on Communication and Adaptive BDI-2 domains were small between those participants who were and were not considered delayed, perhaps limiting the variability seen in these scores between groups. All of the children in the sample were identified as having deficits in at least one BDI-2 domain, thus qualifying them for services through the EarlySteps program. Individuals were reassessed a year or more after their initial assessment, thus indicating that they remained involved or in contact with EarlySteps in some way. This study was limited by the inability to include information regarding the types, amounts, and quality of interventions received by children in the study. Nonetheless, it is promising to note that overall mean DQ scores improved significantly for the Communication and Adaptive domains in those children initially exhibiting deficits in these areas. 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