Reported History of Developmental Regression and Restricted, Repetitive Behaviors in Children with Autism Spectrum Disorders

Phenotypic characteristics and rehabilitation effect of children with regressive autism spectrum disorder: a prospective cohort study

BACKGROUND

In this prospective cohort study, we determined the phenotypic characteristics of children with regressive autism spectrum disorder (ASD) and explored the effects of rehabilitation.

METHODS

We recruited 370 children with ASD aged 1.5-7 years. Based on the Regression Supplement Form, the children were assigned to two groups: regressive and non-regressive. The core symptoms and neurodevelopmental levels of ASD were assessed before and after 1 year of behavioral intervention using the Autism Diagnostic Observation Schedule (ADOS), Social Response Scale (SRS), Children Autism Rating Scale (CARS), and Gesell Developmental Scale (GDS).

RESULTS

Among the 370 children with ASD, 28.38% (105/370) experienced regression. Regression was primarily observed in social communication and language skills. Children with regressive ASD exhibited higher SRS and CARS scores and lower GDS scores than those with non-regressive ASD. After 1 year of behavioral intervention, the symptom scale scores significantly decreased for all children with ASD; however, a lesser degree of improvement was observed in children with regressive ASD than in those with non-regressive ASD. In addition, the symptom scores of children with regressive ASD below 4 years old significantly decreased, whereas the scores of those over 4 years old did not significantly improve. Children with regressive ASD showed higher core symptom scores and lower neurodevelopmental levels. Nevertheless, after behavioral intervention, some symptoms exhibited significant improvements in children with regressive ASD under 4 years of age.

CONCLUSION

Early intervention should be considered for children with ASD, particularly for those with regressive ASD.

The Influence of Social and Developmental Factors on the Timing of Autism Spectrum Disorder Diagnosis of Preschool-Aged Children: Evidence from a Specialized Chilean Center

We investigated the influence of developmental and social factors on the age of autism diagnosis (AoD) in a cohort of toddlers living in Chile. A cross-sectional study was conducted among 509 preschool children diagnosed with autism spectrum disorder [M = 40.2 months (SD = 8.6), girls: 32%] in the neurodevelopmental unit of a university clinic in Santiago, Chile (2015-2023). Structural changes in the annual trend of AoD were tested. Generalized linear models (gamma distribution) with and without interaction terms were used for the multivariate analysis, adjusting for gender, residential area, year of diagnosis, developmental variables (language regression, delayed walking, and use of expressive verbal language), and primary caregiver age and education level (CEL). 95% confidence intervals of the unstandardized regression coefficients (B) were calculated using 1000 bootstrap resampling to estimate associations. AoD increased between 2021-2022 and decreased in 2023. Female gender (B = 2.72 [1.21-4.23]), no history of language regression (B = 3.97 [1.66-6.28]), and the presence of expressive verbal language at diagnosis (B = 1.57 [0.05-3.08]) were associated with higher AoD. Children whose caregivers had tertiary education were diagnosed earlier than those with ≤ 12 years of formal education. Although the influence of CEL increased with caregiver age, differences between CEL groups were significant only for caregivers aged ≥ 30 years. Improved education and early screening for clinical features of autism among healthcare professionals and the community, with a focus on young children without highly apparent developmental concerns and those from vulnerable social groups, are warranted.

Preventive effects of resveratrol against early-life impairments in the animal model of autism induced by valproic acid

Background

Autism Spectrum Disorder (ASD) is a neurodevelopmental condition characterized by social interaction deficits and repetitive/stereotyped behaviors. Its prevalence is increasing, affecting one in 36 children in the United States. The valproic acid (VPA) induced animal model of ASD is a reliable method for investigating cellular, molecular, and behavioral aspects related to the disorder. Trans-Resveratrol (RSV), a polyphenol with anti-inflammatory and antioxidant effects studied in various diseases, has recently demonstrated the ability to prevent cellular, molecular, sensory, and social deficits in the VPA model. In this study, we examined the effects of prenatal exposure to VPA and the potential preventive effects of RSV on the offspring.

Method

We monitored gestational weight from embryonic day 6.5 until 18.5 and assessed the onset of developmental milestones and morphometric parameters in litters. The generalized estimating equations (GEE) were used to analyze longitudinal data.

Results

Exposure to VPA during rat pregnancy resulted in abnormal weight gain fold-changes on embryonic days 13.5 and 18.5, followed by fewer animals per litter. Additionally, we discovered a positive correlation between weight variation during E15.5-E18.5 and the number of rat pups in the VPA group.

Conclusion

VPA exposure led to slight length deficiencies and delays in the onset of developmental milestones. Interestingly, the prenatal RSV treatment not only prevented most of these delays but also led to the early onset of certain milestones and improved morphometric characteristics in the offspring. In summary, our findings suggest that RSV may have potential as a therapeutic intervention to protect against the negative effects of prenatal VPA exposure, highlighting its importance in future studies of prenatal neurodevelopmental disorders.

Risk factors and clinical characteristics of autism spectrum disorder with regression in China

Autism spectrum disorder with regression (ASD-R) is characterized by the loss of previously acquired skills during the initial year of life. This study aimed to investigate the clinical characteristics, patterns of regression, and potential risk factors associated with ASD-R in the Chinese Han population. A case-control study was conducted between September 2020 and March 2022. A total of 186 children were enrolled, including 58 children with ASD-R, 70 with ASD without regression (ASD-NR), and 58 typically developing children. Demographic information, clinical characteristics, and potential risk factors related to ASD-R were assessed using a combination of questionnaires, interviews, and physician assessments. The results revealed that children with ASD-R exhibited more severe impairments in social communication and stereotyped behaviors compared with those with ASD-NR. Language regression, constituting 40% of cases within the ASD-R group, was found to be the most common type of regression. Furthermore, our analysis revealed that fever (OR = 4.01, 95% CI: 1.26-12.76) and diarrhea (OR = 6.32, 95% CI: 1.38-29.03) were identified as significant risk factors for ASD-R. These findings contribute to our understanding of the heterogeneity of ASD and highlight the importance of considering immune responses and gastrointestinal factors in the etiology of ASD-R.

Urine lactate concentration as a non-invasive screener for metabolic abnormalities: Findings in children with autism spectrum disorder and regression

There is increasing evidence that diseases caused by dysfunctional mitochondria (MD) are associated with autism spectrum disorder (ASD). A comprehensive meta-analysis showed that developmental regression was reported in half of the children with ASD and mitochondrial dysfunction which is much higher than in the general population of ASD. The aim of the present exploratory study was to determine lactate concentrations in urine of children with ASD, as a non-invasive large-scale screening method for metabolic abnormalities including mitochondrial dysfunction and its possible association with regression. First, clinical characteristics of MD were examined in 99 children (3–11 years) with ASD. Second, clinical characteristics of MD, severity of ASD and reported regression were compared between children with the 20% lowest lactate concentrations and those with the 20% highest lactate concentrations in urine. Third, clinical characteristics of MD and lactate concentration in urine were compared in children with (n = 37) and without (n = 62) reported regression. An association of urine lactate concentrations with mitochondrial dysfunction and regression could not be demonstrated in our large ASD cohort. However, since ASD children were reported by their parents to show a broad range of phenotypic characteristics of MD (e.g., gastro-intestinal and respiratory impairments), and lactate concentrations in urine are not always increased in individuals with MD, the presence of milder mitochondrial dysfunction cannot be excluded. Development of alternative biomarkers and their implementation in prospective studies following developmental trajectories of infants at elevated likelihood for ASD will be needed in the future to further unravel the association of ASD with mitochondrial dysfunction and eventually improve early detection.

Description of Clinician-Diagnosed Regression at Time of Autism Spectrum Disorder Diagnosis in Toddlers

OBJECTIVE

Previous studies have reported varying rates of regression in children with autism spectrum disorder (ASD). We sought to (1) determine the rate of clinician-diagnosed regression for young children with ASD and (2) compare developmental functioning and ASD symptoms of children with versus without regression.

METHODS

We conducted a retrospective chart review of toddlers (age 18-36 months) with Diagnostic and Statistical Manual-5 ASD. We abstracted cognitive, language, adaptive, and motor functioning standard scores and ASD core symptoms. Regression was defined as "clinician-diagnosed regression accompanied by recommendation for a medical workup." We used propensity scores to match each participant with regression (n = 20) one-to-one with a participant without regression (n = 20). We compared the groups on developmental scores using independent sample t tests and on core ASD symptoms using Pearson's χ 2 test.

RESULTS

Of the 500 children with ASD, n = 20 (4%) had regression (defined above). Children with regression had lower Bayley cognitive and language scores and lower Vineland adaptive scores compared with those without regression (cognitive: 78.0 vs 85.5, p < 0.05; language: 56.9 vs 68.2, p < 0.01; adaptive: 70.0 vs 80.3; p < 0.01). There was no difference in motor scores across groups. There were no significant differences in the frequency of exhibiting core ASD symptoms for those with versus without regression.

CONCLUSION

In this clinical sample of children with ASD, regression was diagnosed in a small percentage (4%). Those with regression had lower cognitive, language, and adaptive skills compared with those without regression. Rates of clinician-diagnosed regression referred for medical workup are significantly lower than prior estimates based on parent report.

A Multi-Center Study on the Relationship Between Developmental Regression and Disease Severity in Children With Autism Spectrum Disorders

INTRODUCTION

This study aimed to investigate the prevalence of developmental regression in children with Autism Spectrum Disorder (ASD) and to explore its relationship with disease severity.

METHODS

We finally included 1,027 ASD children aged 2-5 years from 13 cities in China: 138 with regressive ASD and 889 with non-regressive ASD. The Social Responsiveness Scale (SRS), Autism Behavior Checklist (ABC), Child Autism Rating Scale (CARS), and Children Neuropsychological and Behavioral Scale-Revision 2016 (CNBS-R2016) were used to evaluate the core symptoms and developmental status of children in the two groups.

RESULTS

Among the 1,027 ASD children eventually included, 138 (13.44%) cases showed regressive behavior and the average regression occurring age was 24.00 (18.00-27.00) months. Among the regressive children, 105 cases (76.09%) had language regression, 79 cases (57.25%) had social regression, and 4 cases (2.90%) had motor regression. The total scores of ABC and the sub-score of sensory and stereotypic behavior (β = 5.122, 95% CI: 0.818, 9.426, P < 0.05; β = 1.104, 95% CI: 0.120, 2.089, P < 0.05; β = 1.388, 95% CI: 0.038, 2.737, P < 0.05), the SRS total scores and the sub-score of autistic mannerisms (β = 4.991, 95% CI: 0.494, 9.487, P < 0.05; β = 1.297, 95% CI: 0.140, 2.453, P < 0.05) of children in the regressive group were all higher than the non-regressive group. The total developmental quotient (DQ) of CNBS-R2016 and the DQ of gross motor, fine motor, adaptive behavior, language (β = -5.827, 95% CI: -11.529, -0.125, P < 0.05) and personal society in the regressive group were lower than the non-regressive group and the proportion of children with intelligent developmental impairment was higher the non-regressive group.

CONCLUSION

Regressive autism is mainly manifested as language and social regression. Children with regressive ASD have more severe core symptoms, lower neurodevelopmental level DQ, and more serious disease degree than children with non-regressive ASD, which requires further etiological examinations and more clinical attention.

Children with ASD and Communication Regression: Examining Pre-Loss Skills and Later Language Outcomes Through the Preschool Years

This study investigated receptive and expressive language outcomes in children with autism spectrum disorder (ASD) with and without a history of language/communication regression, employing three progressively less stringent definitions of regression. Data were derived from a large, longitudinal sample of children with ASD in which regression was assessed at approximately 30 months. Results indicated poorer receptive language and larger discrepancies between receptive and expressive language in the regression group than the group without regression at 44 months but not 66 months. Number of words used before loss predicted receptive language at 44 months. Overall, results suggest that a regression profile in ASD is associated with modest and transient impacts on language outcomes that are no longer discernable at school entry.

Bayonet-shaped language development in autism with regression: a retrospective study

Background

Language delay is one of the major referral criteria for an autism evaluation. Once an autism spectrum diagnosis is established, the language prognosis is among the main parental concerns. Early language regression (ELR) is observed by 10–50% of parents but its relevance to late language level and socio-communicative ability is uncertain. This study aimed to establish the predictive value of ELR on the progression of language development and socio-communicative outcomes to guide clinicians in addressing parents’ concerns at the time of diagnosis.

Methods

We used socio-communicative, language, and cognitive data of 2,047 autism spectrum participants from the Simons Simplex Collection, aged 4–18 years (mean = 9 years; SD = 3.6). Cox proportional hazard and logistic regression models were used to evaluate the effect of ELR on language milestones and the probability of using complex and flexible language, as defined by the choice of ADOS module at enrollment. Linear models were then used to evaluate the relationship of ELR and non-verbal IQ with socio-communicative and language levels.

Results

ELR is associated with earlier language milestones but delayed attainment of fluent, complex, and flexible language. However, this language outcome can be expected for almost all autistic children without intellectual disability at 18 years of age. It is mostly influenced by non-verbal IQ, not ELR. The language and socio-communicative level of participants with flexible language, as measured by the Vineland and ADOS socio-communicative subscales, was not affected by ELR.

Limitations

This study is based on a relatively coarse measure of ultimate language level and relies on retrospective reporting of early language milestones and ELR. It does not prospectively document the age at which language catches up, the relationship between ELR and other behavioral areas of regression, nor the effects of intervention.

Conclusions

For autistic individuals with ELR and a normal level of non-verbal intelligence, language development follows a “bayonet shape” trajectory: early first words followed by regression, a plateau with limited progress, and then language catch up.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13229-021-00444-8.

Factors Associated with Restricted, Repetitive Behaviors and Interests and Diagnostic Severity Level Ratings in Young Children with Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by restricted, repetitive patterns of behavior and interests (RRBIs). With the latest update to the Diagnostic and Statistical Manual of Mental Disorders, a severity level rating is assigned to the two core features of ASD (American Psychiatric Association in Diagnostic and statistical manual of mental disorders 5 American Psychiatric Association Washington, D.C., 2013). Previous studies have identified factors associated with RRBI severity; however, the relationship among RRBIs, adaptive functioning, and diagnostic severity level remains unclear. The present study investigated whether adaptive functioning and parent-reported ASD symptoms predict RRBI severity in young children with ASD. Additionally, a fine-grained analysis was conducted to examine the factors associated with diagnostic severity level ratings. Several significant associations were found. Study findings and implications for assessment and treatment of RRBIs are discussed.

Brief Report: Health-Related Quality of Life in Preschoolers with Autism Spectrum Disorder is Related to Diagnostic Age and Autistic Symptom Severity

We conducted a cross-sectional study to explore whether clinical characteristics and autism diagnostic-traits severity are associated with caregiver-reported impairment of health-related quality of life (Pediatric Quality of Life Inventory Generic Core Scales, Fourth Edition) in 93 Chilean toddlers (age: 2-4 years) with autism spectrum disorder. Median total scale, physical health, and psychosocial health scores were 76 (IQR 70-81), 88 (IQR 81-94), and 71 (IQR 62-79), respectively. In multiple-regression analysis, diagnostic age (β = 0.219; p 0.021) and Calibrated Severity Score of Autism Diagnostic Observation Schedule, second edition (β = - 0.434; p < 0.001) were independently correlated to the total scale score. Lower age and higher autistic traits severity at diagnosis are correlated with worse well-being perception by caregivers.

Prevalence and Age of Onset of Regression in Children with Autism Spectrum Disorder: A Systematic Review and Meta-analytical Update

A systematic review published in 2013 reported 32% of children on the autism spectrum experience skill loss, known as autistic regression. However, the frequency varied depending on definition and measures used to capture skills. Retrospective parent report and prospective observation indicate loss of language and/or social skills, with motor skills typically unaffected. Our aim was to update the prevalence and age of onset of autistic regression through a meta-analysis of the literature to understand if there have been changes to the reported onset and prevalence since 2010. A systematic literature search was conducted using Medline, Embase, PsycINFO, and the Cochrane Library databases and included studies published from 2010 onward. Risk of bias assessment was performed on included studies. A random effects model was used to calculate the pooled prevalence and age of onset of autistic regression. Ninety-seven studies were included in the systematic review, of which 75 studies involving 33,014 participants had sufficient data for meta-analytic syntheses. The pooled proportion of autistic regression was 30% (95% confidence interval [CI]: 27-32%) but heterogeneity was high (I² = 96.91) and did not reduce with sensitivity or subgroup analyses based on study design or clinical differences, respectively. Prevalence varied according to risk of bias (low: 27%) and definition of regression (language: 20%, language/social: 40%, mixed: 30%, and unspecified: 27%). Weighted average age of onset was 19.8 months. Findings from this meta-analysis highlight the importance of developing a standardized definition of autistic regression, and tools to measure this at multiple time points during early childhood development. LAY SUMMARY: About a third of children with Autism Spectrum Disorder experience loss of skills, which is also known as autistic regression. This paper provides an update of the rate of autistic regression in children and the age when they first experience loss of skills, based on current studies. The findings from this review contribute to our understanding of the onset patterns of autistic regression. Unfortunately, studies are not sufficiently similar, making it difficult to provide clear answers on the exact timing or type of regression seen in different children.

Children With Autism Spectrum Disorder and Neurodevelopmental Regression Present a Severe Pattern After a Follow-Up at 24 Months

This study examined the presence of neurodevelopmental regression and its effects on the clinical manifestations and the severity of autism spectrum disorder (ASD) in a group of children with autism compared with those without neurodevelopmental regression at the time of initial classification and subsequently. Methods and Subjects: ASD patients were classified into two subgroups, neurodevelopmental regressive (AMR) and non-regressive (ANMR), using a questionnaire based on the Autism Diagnostic Interview-Revised test. The severity of ASD and neurodevelopment were assessed with the Childhood Autism Rating Scale Test-2, Strengths and Difficulties Questionnaire, and Pervasive Developmental Disorders Behavior Inventory Parent Ratings (PDDBI) and with the Battelle Developmental Inventory tests at the beginning of the study and after 24 months of follow-up. Fifty-two patients aged 2-6 years with ASD were included. Nineteen were classified with AMR, and 33 were classified with ANMR. Results: The AMR subgroup presented greater severity of autistic symptoms and higher autism scores. Additionally, they showed lower overall neurodevelopment. The AMR subgroup at 24 months had poorer scores on the Battelle Developmental Inventory test in the following areas: Total personal/social (p < 0.03), Total Motor (p < 0.04), Expressive (p < 0.01), and Battelle Total (p < 0.04). On the PDDBI test, the AMR subgroup had scores indicating significantly more severe ASD symptoms in the variables: ritual score (p < 0.038), social approach behaviors (p < 0.048), expressive language (p < 0.002), and autism score (p < 0.003). Conclusions: ASD patients exhibited a set of different neurological phenotypes. The AMR and ANMR subgroups presented different clinical manifestations and prognoses in terms of the severity of autistic symptoms and neurodevelopment.

Early Autism Diagnosis in the Primary Care Setting

As the prevalence of autism spectrum disorder (ASD) has increased in recent years, so too has the body of research describing the importance of early diagnosis and early intervention. Unfortunately, a large proportion of children with the disorder do not receive a diagnosis until after their fourth birthday. Various reasons exist for late diagnosis, including limited understanding of nuanced early warning signs and limited knowledge of effective early detection mechanisms among healthcare providers. Since early diagnosis enables access to treatment, and early intensive intervention improves long-term developmental outcomes, early detection by pediatric healthcare providers is critical. This article will review ASD prevalence rates, describe correlates and factors that might influence prevalence estimates, and highlight recent advances in early detection methods and intervention services.

Autism Spectrum Disorder as a Brain-Gut-Microbiome Axis Disorder

While there are numerous medical comorbidities associated with ASD, gastrointestinal (GI) issues have a significant impact on quality of life for these individuals. Recent findings continue to support the relationship between the gut microbiome and both GI symptoms and behavior, but the heterogeneity within the autism spectrum requires in-depth clinical characterization of these clinical cohorts. Large, diverse, well-controlled studies in this area of research are still needed. Although there is still much to discover about the brain-gut-microbiome axis in ASD, microbially mediated therapies, specifically probiotics and fecal microbiota transplantation have shown promise in the treatment of GI symptoms in ASD, with potential benefit to the core behavioral symptoms of ASD as well. Future research and clinical trials must increasingly consider complex phenotypes in ASD in stratification of large datasets as well as in design of inclusion criteria for individual therapeutic interventions.

Characteristics, Early Development and Outcome of Parent-Reported Regression in Autism Spectrum Disorder

This study explored regression patterns in 100 children with ASD (3-11 years) using several approaches to enhance the validity of retrospective parent report. Both early development and outcome were examined in regression groups defined by 36 months age cut-off and two underlying empirical patterns based on type and onset age. Results over regression groups were generally consistent. During early development, children with regression showed a similar amount of social atypicalities and stereotyped behaviour as compared to children without regression. However, parents indicated less communication skills which could be a valuable predictor of regression. Development after regression was characterised by early language delay and more restricted and repetitive behaviour. The findings provide insight into the diagnosis and prognosis of regression in ASD.

Identification, Evaluation, and Management of Children With Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a common neurodevelopmental disorder with reported prevalence in the United States of 1 in 59 children (approximately 1.7%). Core deficits are identified in 2 domains: social communication/interaction and restrictive, repetitive patterns of behavior. Children and youth with ASD have service needs in behavioral, educational, health, leisure, family support, and other areas. Standardized screening for ASD at 18 and 24 months of age with ongoing developmental surveillance continues to be recommended in primary care (although it may be performed in other settings), because ASD is common, can be diagnosed as young as 18 months of age, and has evidenced-based interventions that may improve function. More accurate and culturally sensitive screening approaches are needed. Primary care providers should be familiar with the diagnostic criteria for ASD, appropriate etiologic evaluation, and co-occurring medical and behavioral conditions (such as disorders of sleep and feeding, gastrointestinal tract symptoms, obesity, seizures, attention-deficit/hyperactivity disorder, anxiety, and wandering) that affect the child's function and quality of life. There is an increasing evidence base to support behavioral and other interventions to address specific skills and symptoms. Shared decision making calls for collaboration with families in evaluation and choice of interventions.  This single clinical report updates the 2007 American Academy of Pediatrics clinical reports on the evaluation and treatment of ASD in one publication with an online table of contents and section view available through the American Academy of Pediatrics Gateway to help the reader identify topic areas within the report.

Autism With and Without Regression: A Two-Year Prospective Longitudinal Study in Two Population-Derived Swedish Cohorts

Two community-based cohorts of children with autism spectrum disorder, examined using similar assessment protocols, were pooled (n = 301) and subdivided according to history of regression. Those with regression (n = 62), 20.5% of the combined cohort, were contrasted with those without regression (n = 241) at first assessment (age range 19–60 months) and at 2-year follow-up on a range of measures. The regression group was significantly more functionally impaired, with regard to intellectual function (p < .001), language development (p < .001), and to severity of autism (p < .01) at both T1 and T2. Only 14 (23.3%) had a clearly identified underlying etiology [24 (18.6%) in the non-regressive group]. There were no significant differences between those who had regressed ‘from normal’ and those who had regressed ‘from low’ functioning.

Regression in autism spectrum disorder: A critical overview of retrospective findings and recommendations for future research

Historically, two onset patterns in autism spectrum disorder (ASD) were described: early onset of symptoms and regression in which one-third appear to show a loss of previously established skills in the second year of life. Since this phenomenon could represent a distinct ASD subtype and provide more insight into the etiology, diagnosis, and prognosis, many studies have compared these two groups. The present review discusses definitions, etiology, and methods used in research with a retrospective design and provides an overview of the results on early development and outcomes. However, retrospective research has not provided clear answers on regression as a distinct subtype of ASD and the historic division between early onset and regression does not seem to fit the empirical findings. Based on inconsistent results, future research on onset patterns in ASD needs to be more systematic on the definitions and methods used. Several recommendations to enhance the reliability of future retrospective results are discussed. The combination of a categorical and dimensional approach provides a new interesting framework.

Regression in autism spectrum disorder: Reconciling findings from retrospective and prospective research

The way in which the behavioral manifestations of autism spectrum disorder (ASD) emerge in infancy is variable. Regression-loss of previously acquired skills-occurs in a subset of children. However, the etiology and significance of regression remains unclear. Until recently, investigation of regression relied on retrospective report by parents or examination of home videos from early in life. However, home videos and retrospective report of the nature and timing of regression, and association with factors such as illness or immunization, is potentially subject to bias. The advent of prospective studies of infant siblings at familial high-risk of ASD has the potential to document regression as it occurs. Recent research has suggested that subtle loss of skills occurs in a larger proportion of children with ASD than previously assumed; however, there are few reports of clear-cut regressions, such as that involving dramatic loss of language and other established skills, in the prospective literature. This could be because of the following: clear-cut regression occurs less commonly than parent report suggests, study design limits the potential to detect regression, or there are differences between multiplex and simplex families in the rate of de novo genetic mutations and therefore regression risk. This review will bring together literature from retrospective and prospective research and attempt to reconcile diverging findings, with a specific focus on methodological issues. Changing conceptualizations of regression will be discussed, as well as etiological factors that may be associated with regression. The main challenges that need to be addressed to measure regression in prospective studies will be set out. Autism Research 2018, 11: 1602-1620. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Regression-a loss of previously established skills-occurs in a subset of children with ASD. Parental recall is not always accurate but studying younger siblings of children with ASD, 10-20% of whom will develop ASD, should make it possible to measure regression as it occurs. Clear-cut regression, like loss of language, has not often been reported in infant sibling studies, but recent research suggests that gradual loss of social engagement might be more common. This review looks at the evidence for regression from infant sibling studies and asks how study design affects the likelihood of capturing regression.

Characterizing regression in Phelan McDermid Syndrome (22q13 deletion syndrome)

PURPOSE

To describe the frequency and characteristics of developmental regression in a sample of 50 patients with Phelan McDermid Syndrome (PMS) and investigate the possibility of association between regression, epilepsy, and electroencephalogram (EEG) abnormalities and deletion size.

METHODS

The Autism Diagnostic Interview-Revised (ADI-R) was used to evaluate regression in patients with a confirmed diagnosis of PMS. Information on seizure history and EEGs was obtained from medical record review. Deletion size was determined by DNA microarray.

RESULTS

A history of regression at any age was present in 43% of all patients. Among those exhibiting regression, 67% had onset after the age of 30 months, affecting primarily motor and self-help skills. In 63% of all patients there was a history of seizures and a history of abnormal EEG was also present in 71%. No significant associations were found between regression and seizures or EEG abnormalities. Deletion size was significantly associated with EEG abnormalities, but not with regression or seizures.

CONCLUSION

This study found a high rate of regression in PMS. In contrast to regression in autism, that often occurs earlier in development and affects language and social skills, we found regression in PMS most frequently has an onset in mid-childhood, affecting motor and self-help skills. We also found high rates of seizures and abnormal EEGs in patients with PMS. However, a history of abnormal EEG and seizures was not associated with an increased risk of regression. Larger deletion sizes were found to be significantly associated with a history of abnormal EEG.