Onset of Repetitive Behavior/Restricted Interests and Loss of Skills in Young Children with Autism

Background: Although onset of repetitive behaviors in autism is now known to occur as young as the second year of life (Cox et al., 2003), little is known about whether the onset of these symptoms relates to reports of skill losses in children diagnosed with autism.

Objectives: This study examined the timing of skill loss in comparison to the onset of specific repetitive behaviors in young children with autism.

Methods: Parents of 61 children (45 autism, 16 PDD-NOS; mean age 35.8 months) were interviewed with the Autism Diagnostic Interview – Toddler version to determine timing of symptom onset and loss of skills, in a study recruiting children with autism - both with and without histories of regression.  The following 10 repetitive behaviors/restricted interests were examined: unusual preoccupations, circumscribed interests, repetitive use of objects/interest in parts of objects, compulsions/rituals, unusual sensory interests, difficulty with minor changes in child’s routine, resistance to trivial changes in the environment, unusual attachment to objects, hand and finger mannerisms, and other complex mannerisms.

Results: Preliminary analyses find a loss of language (i.e. words, vocalizations, babbling, communicative intent, or cooing) and/or social skills (i.e. social engagement and responsiveness) was reported in 33 of the 61 children (33 with language loss, 26 with loss of social skills), with a mean age of earliest loss at 16.9 months.  The average age of reported first symptoms of autism was 13.5 months for the whole group, and 14.6 for the loss subgroup.

The most commonly reported early repetitive behaviors/restricted interests were: repetitive use of objects (90%), unusual sensory interests (82%), hand and finger mannerisms (67%), and complex mannerisms (70%). The average age of onset (earliest reported) of any repetitive behavior was 14.3 months.

Of the 33 children with reported losses, 21 (64%) had reported repetitive behavior (in at least one area) at least one month prior to age of loss. Nine of the 21 children with repetitive behavior prior to loss also had this type of behavior reported by parents as a first concern, compared with none of the 12 children with repetitive behavior onset after losses.  Significantly earlier ages of onset were reported for repetitive use of objects and unusual sensory interests in children with repetitive behavior prior to losses.

Conclusions: Many parents of children who reported skill losses also reported an earlier onset of repetitive behaviors, with some reporting these to be among their first concerns.  These findings are consistent with reports of “lower level” or “repetitive sensorimotor” symptoms (Richler , 2007), that require fewer cognitive and language skills than others, and may be more likely to present themselves quite early. Further study should investigate how these types of early symptoms relate to reported social and communication losses, as they may provide clinicians with earlier diagnostic signals.