At-a-Glance

Infants that are later diagnosed with autism exhibit differences in social communication skills at 9 to 12 months of age.

Background: Differences in social communication are a key feature of autism but can be difficult to detect at early ages. Such effects might be expected at 9 to 12 months of age, when infants begin developing observable social communication skills such as gesture, eye gaze, and facial expression. However, while ASD can be diagnosed as early as 14 months, few studies have assessed communication skill development from 9 to 12 months. Understanding differences in social communication skill development could support potential ASD diagnosis in even younger infants.

Methods & Findings: This study aimed to determine whether 9- to 12-month-old infants who were later diagnosed with ASD displayed differences in social communication skills during this key stage of early communication development. A group of 124 infants enrolled in a prospective longitudinal study (i.e., a study design that follows the same people over a period of time) were given a special standardized communication assessment at 9 months and again at 12 months of age by a speech-language pathologist with expertise in autism. Each infant received a score based on categories including emotion and eye gaze, gesture, vocalization, understanding, and object use. Later, at 24 months of age, all participating infants received diagnostic evaluation for ASD by a licensed clinical psychologist and speech-language pathologist. The 30 infants who were diagnosed with ASD scored significantly lower on most areas of social communication at 9 months and on all but one area at 12 months compared to typically developing children (i.e., no ASD diagnosis). Race, maternal education, and family income did not significantly impact the findings of this study.

Implications: These results demonstrate how autism can affect the development of communication skills in early infancy. Furthermore, this study identifies a small but foundational set of skills (e.g., eye gaze, facial expression, and sounds) that distinguish 9- and 12-month-old infants who go on to be diagnosed with autism from typically developing infants. This may help inform the development and improvement of early ASD screening tests and interventions. Because this study successfully detected communication differences in infants later diagnosed with ASD, future studies can explore the relationship between brain activity and these differences during early stages of communication development to aid in the design of new diagnostic and screening tools.

At-a-Glance

Among infant siblings of children with autism, those later diagnosed with autism vocalize less at 12 months than their neurotypical peers.

Background: Clinicians often assess children for autism because of parental concerns about their child's language development. However, infants who are eventually diagnosed with ASD show a wide range of vocal communication differences at 12 to 24 months of age. Some previous studies have found that infants later diagnosed with ASD vocalize less than those not diagnosed with ASD, while studies that include infant siblings of children with autism, who may be more likely to receive an ASD diagnosis, have generated more mixed results. This mixed evidence base has made it difficult to pursue the use of vocalizations as a diagnostic indicator.

Methods & Findings: This study aimed to assess vocalization differences between infants who have an older sibling with autism (higher likelihood of a later diagnosis of ASD) and infants who do not have an older sibling with autism (lower likelihood of an ASD diagnosis). Specifically, the researchers focused on measuring speech-like vocalizations (sounds that are found in adult speech and are precursors to language, such as single consonants and vowels, babbles, and words). Video recordings were taken of infants at 6, 12, and 24 months of age as they interacted with their caregiver and a clinician. The infants were screened for ASD at 24 months of age. The researchers compared the vocalizations of infant siblings later diagnosed with ASD, infant siblings not diagnosed with ASD, and infants who do not have a sibling with ASD. The study found that at 12 months, the infant siblings who did not later receive an ASD diagnosis produced more vocalizations than the infant siblings who were later diagnosed with ASD. Infants without a sibling with ASD did not exhibit a distinctive vocalization pattern. At 24 months, the neurotypical infant siblings produced more vocalizations and more speech-like vocalizations than both the infant siblings later diagnosed with ASD and the infants without a sibling with ASD. However, neurotypical infant siblings did not exhibit above-average language skills overall, as measured by a standardized language test.

Implications: Findings from this study provide support that video-based assessments of vocalizations can be a promising tool for future studies of infant siblings of children with ASD. In addition, this study provides evidence that identifying decreased vocalization in infant siblings of children with ASD can help diagnose ASD earlier and guide early intervention efforts. The researchers plan to develop techniques that can identify more detailed aspects of speech-like and non-speech-like vocalizations.

At-a-Glance

Regression in early communication skills does not have a long-term impact on the future language skills of children with autism.

Background: Early in life, many children with autism appear to lose certain skills in a process called regression. Language and communication regression is particularly common and is not well understood. To date, no studies of language regression have focused on receptive language skills (i.e., the ability to understand language), and few studies have addressed loss of preverbal communication skills (such as cooing, babbling, vocal imitating) and their relationship to later language skills in children who experience regression. This study aimed to fill this gap by examining how language regression may differ depending on pre-verbal and verbal communication skills attained prior to regression and how regression impacts later language skills in preschool.

Methods & Findings: The researchers used data from 129 preschool-aged children with autism to study language outcomes. First, caregivers were interviewed to obtain information about children's communication skills and number of words used. Beginning at approximately 2.5 years of age, children completed multiple diagnostic, cognitive, and language assessments during three to four visits with a psychologist over the course of about four years. The researchers found several differences at Visit 2 (when children were an average age of 3.7 years) between children who previously had lost communication skills and those who had not lost skills. Children who had previously lost fewer communication skills had better receptive language skills than children who had previously lost more communication skills. In addition, the children who used more words before experiencing regression had stronger receptive and expressive language skills at Visit 2. However, in all cases, these differences were small in magnitude and had disappeared by Visit 4 (when children were an average age of 5.5 years).

Implications: Children in this study demonstrated different levels of pre-verbal and verbal communication skills prior to regression. Given this range, these children likely experience different rates of language development. Importantly, the reduction of differences by Visit 4 suggest that regression does not cause long-term effects on language skills (although longer-term longitudinal follow up is needed to confirm this). This finding suggests that autistic children who experience language regression would likely benefit from specialized speech-language interventions individualized to their unique language learning profile.