Medical researchers have uncovered a long list of genetic factors that can lead to neurodevelopmental disorders such as autism, but it's still difficult to predict from genetics alone whether a child will develop autism, and how severe the disorder will be. Bucknell University Professor David Evans, psychology, has developed a screening method that can improve those predictions by assessing not only a child's behavior, but the habits and routines of the child's parents as well.
Published in January in the Journal of the American Academy of Child & Adolescent Psychiatry, a study led by Evans examined two broad patterns of behavior appearing in neurodevelopmental disorders from autism to obsessive-compulsive disorder (OCD) to Tourette's syndrome: repetitive behaviors and what Evans calls rigidity — an insistence on uniformity that could manifest as a need to arrange objects in straight lines or adhere to strict daily routines.
"We might be able to predict the severity of a child's autism by looking at the degree, intensity and frequency of repetitive behaviors in the parents — even if the parents don't have a disorder," Evans said.
"Repetitive behavior, like IQ or height, is complex and heritable," he continued. "There's no single gene for determining height, but we can estimate a child's height by looking at the parents' heights. In the same way, we can now estimate the child's repetitive behavior, and ultimately the child's risk of developing a repetitive-behavior disorder, by looking at the parents."
The study revealed a significant correlation between repetitive and rigid behaviors in parents and their children, validating the theory that repetitive and rigid behaviors in parents are a useful indicator of a child's risk for certain neurodevelopmental disorders. It also provided a rich set of data about the prevalence of these behaviors in the general population.
"This measure helps us understand the wide range of repetitive behavior and the boundaries of what's normal or what's not," Evans said. "It tells us how much repetitive behavior is normal for a 1-year-old, how much is normal for a 2-year-old, and so on. We can chart this at each age and use it to identify kids who might be at risk for autism, OCD, Tourette's syndrome, or other neurodevelopmental or neuropsychiatric disorders that are marked by repetitive behavior."
Those findings are critically needed because neurodevelopmental disorders exist on spectrums of intensity, and many of the habits the surveys asked about are common in the general population. For example, Evans noted that there isn't necessarily anything unusual about a 2-year-old developing a daily pre-bedtime routine, even though such a routine could be characterized as rigid or repetitive. When it comes to such activities, the results of Evans' study will provide clinicians an indication of how much is too much.
To reach these results, Evans and the study's co-authors, a group from several other institutions that includes Evans' former student Laina Lusk '13, surveyed a nationally representative group of 3,108 parents and 3,032 children — the first time researchers have examined these behaviors in a sample representative of the general population. Respondents were provided a lists of habits and traits and asked to rate how much they applied to their own lives or the lives of their children on a five-point scale, ranging from "not at all/never" to "very much/always." Questions included "Do you notice when pictures on walls are not lined up, or are crooked," "Do you prefer to finish one task before moving on to the next," and "Does your child notice when objects are out of place or not arranged 'just right?' "
The similarity of questions between the two surveys (the child and adult versions) is an important feature, Evans noted, since it allows for a more direct comparison between children and their parents. "Most other measures of autism measure kids one way, and then use a different kind of assessment for adults" he said. "This, at least with repetitive behaviors, suggests that we can now compare children to their parents directly, and can compare children longitudinally over time."
The surveys are also a more sensitive instrument for assessing repetitive and rigid behaviors than existing surveys that assess only severe behaviors, and might not pick up on repetitive and rigid behaviors in individuals that don't reach the threshold of a neurodevelopmental disorder. This is also an important feature since these disorders reflect spectrums of behavior.
"We tend to think of autism as if it's all or nothing — you've got it or you don't," Evans said. "What this study tells us is that we need to look at the symptoms as dimensions. It's not all or none — you can have a little bit, you can have a lot, you can have a moderate amount."
Evans next plans to expand his study to examine larger groups of people with autism and other neurodevelopmental disorders in their families, as well as to more closely examine the range of repetitive behaviors found within neurodevelopmental syndromes and explore the connections between these behaviors and the biology of the brain.
"We think that these measures will be useful early screeners to help clinicians diagnose autism and other disorders," he said.