Diagnoses of autism spectrum disorder (ASD) in children as young as 14 months are remarkably stable

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The focus of this review is on the early identification, assessment, and treatment of young children (0–5 years of age) with autism spectrum disorders (ASDs).

ASDs are diagnosed in approximately 1 out of 150 children in the United States,1,2 and given the increasing evidence that early intervention improves outcomes for children with ASD, there is an urgent need to enhance early detection and intervention efforts.3 

Retrospective parent reports,4,5 early home videotapes,6,7 and newer prospective studies of younger siblings of children with ASD who are at elevated risk 8,9 provide converging evidence that the age at onset for the majority of cases of ASD is the second year of life.

We first review the early signs and symptoms of ASD, then describe some of the measures that can be employed for screening and diagnosis, discuss the family context with respect to both adaptation to diagnosis and treatment, and conclude with a brief review of interventions for young children with ASD.

Traditionally, the term pervasive developmental disorders (PDDs) has been employed in the Diagnostic and Statistical Manual of Mental Disorders, fourth edition, text revision (DSM-IV-TR), referring to autistic disorder, Asperger’s disorder, PDD not otherwise specified (PDD-NOS), childhood disintegrative disorder, and Rett Disorder.10 

In this article, we use the term ASDs to refer to the diagnostic category of PDDs. Specifically, we focus on the diagnosis of autistic disorder (AD) and PDDNOS, as the majority of research on young children has focused on these conditions.

Our preference for the term ASD reflects recognition that along with restrictive interests and repetitive behaviors, the primary developmental perturbations that characterize ASDs are social and communicative in nature.

Moreover, the term ASD reflects an understanding that symptoms and behaviors in these three domains are best quantified as continuous phenomena.11

Although these behaviors lie on a continuum in the general population, individuals with ASD are characterized by severe and pervasive impairments in reciprocal social interaction and communication and exhibit stereotyped behaviors, as well as restricted interests, and activities. To meet full criteria for a DSM-IV diagnosis of AD, a child must demonstrate the following symptoms (Table 1):

  1. Qualitative impairment in social interaction as manifested by two of the following: impairment in the use of multiple nonverbal behaviors (eg, eye gaze, facial expression, body postures), failure to develop peer relationships, lack of sharing of enjoyment, or lack of social or emotional reciprocity.
  2. Qualitative impairment in communication in at least one of the following areas: delay or total lack of spoken language, marked impairment in the ability to initiate or sustain a conversation with others, stereotyped or repetitive use of language, or lack of varied spontaneous play.
  3. Restricted repetitive and stereotyped patterns of behaviors, interests, and activities as manifested by preoccupation with one or more restricted patterns of interests, inflexible adherence to nonfunctional routines or rituals, repetitive motor mannerisms, or preoccupation with parts of objects.

Table 1

Diagnostic criteria for autistic disorder

Domains Involved in ASD SymptomatologyRelated Areas Impaired or Delayed
Social interactionNonverbal behaviors
Peer relationships
Sharing of enjoyment
Social and emotional reciprocity
CommunicationSpoken language
Conversation abilities
Spontaneous play
Restricted and repetitive behaviorsPreoccupation with restricted interests
Motor mannerisms
Preoccupation with parts of objects
Nonfunctional routines and rituals

A diagnosis of PDD-NOS is assigned when the child does not meet full criteria for AD or any other ASD but has marked severe and pervasive impairment in the development of reciprocal social interaction skills and in communication skills or exhibits stereotyped behaviors.10

Particularly before the age of 3 years, distinctions between AD and PDD-NOS may be less meaningful due to low stability across these two disorders.12,13 

Thus, when children receive a diagnosis of PDD-NOS or AD prior to age 3 years, they are likely to remain on the spectrum (albeit less likely than older children), but there is little specificity across these 2 conditions.

A study suggests that up to 50% of PDD-NOS cases could have been overdiagnosed, whereas around 22% of cases were underdiagnosed.12 

By the age of 4 years, the stability of diagnostics has shown to improve significantly (80%–88% stability rate) and is comparable to that observed in older children and adolescents.14,15

Prior to evaluating a young child, it is essential to be knowledgeable about normative infant and toddler development as well as other early emerging psychopathological conditions.

This is particularly important with children under the age of 2 years, as delays or losses of age-appropriate social and communicative skills are often central to making a differential diagnosis of ASD.1618 

In addition, young children with extreme temperamental inhibition, other regulatory challenges, or anxiety disorders or those who have been exposed to trauma may be socially reticent in a novel setting with a new evaluator.

Thus, they may evidence unusual eye contact and restricted pretend play and may even engage in repetitive behaviors.

Therefore, in addition to learning the signs of ASD in young children, a firm grounding in normative development and infant-toddler mental health is requisite to reliable differential diagnosis.

The Update…. 2019

Diagnoses of autism spectrum disorder (ASD) by trained professionals in children as young as 14 months are remarkably stable, suggesting that accurate screening and earlier treatment is feasible, report scientists at University of California San Diego School of Medicine in a study publishing online April 29, 2019 in JAMA Pediatrics.

Growing evidence suggests ASD has its origins in prenatal life – most likely during the first or second trimester of pregnancy – and children begin to display symptoms of the condition by their first birthdays, such as failing to respond to their names or positively interact with others.

Early diagnosis of ASD means earlier intervention and improved therapeutic benefit.

“The sooner you can address issues of ASD, the better the outcome for the child,” said the study’s first author, Karen Pierce, Ph.D., professor of neurosciences and co-director of the UC San Diego Autism Center of Excellence.

She led the study with senior author Eric Courchesne, Ph.D., also a professor of neurosciences.

Multiple studies, including research conducted by Pierce, have found that simple parent checklists performed at the child’s first birthday can identify symptoms of ASD. And yet the mean age of ASD diagnoses in the United States, write the researchers, is “often years later, generally between ages three and four.”

Pierce said the lag between the first signs of ASD and diagnosis represents a missed opportunity, particularly given the accelerated pace of brain development in the first years of life.

“Synaptic density or connections between neurons in the prefrontal and temporal cortex, brain regions centrally involved in higher order social behavior, doubles between birth and one to two years in age,” said Pierce.

“It’s conceivable that outcomes for children with autism could be improved if treatment occurred during this period of rapid brain growth, rather than after, which is more commonly the case.”

To conduct their study, Pierce and colleagues assessed 1,269 toddlers from the general population (441 ASD, 828 non-ASD) who received their first diagnostic evaluation between 12 and 36 months and at least one subsequent evaluation, all by licensed psychologists.

Diagnoses ranged from ASD and features of ASD to language and developmental delay or other developmental issues.

The overall diagnostic stability for ASD was 0.84, higher than for any other diagnostic group.

Only 2 percent of toddlers initially considered to have ASD transitioned to later diagnoses of typical development. Within the group diagnosed with ASD, the most common transition was from ASD to ASD features at 9 percent.

Diagnostic stability of ASD was weakest at 12 to 13 months, just 0.50, but increased to 0.79 by 14 months and 0.83 by 16 months.

Twenty-four percent of toddlers were not designated as ASD at their first evaluations, but later identified.

The most common transition in this group was an initial designation of developmental delay (25 percent) or language delay (16 percent), transitioning to later-onset ASD.

“Our findings suggest that an ASD diagnosis becomes stable starting at 14 months, and overall is more stable than other diagnoses, such as language or developmental delay,” said Pierce.

“Once a toddler is identified as ASD, there is an extremely low chance that he or she will test within typical levels at age three or four, so it’s imperative that we use every effective tool as early as we can to begin treating diagnosed children to the benefit of them and their families over the long-term.”

More information:JAMA Pediatrics (2019). DOI: 10.1001/jamapediatrics.2019.0624
Journal information: JAMA Pediatrics
Provided by University of California – San Diego

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