Measuring autistic traits in the general population: a systematic review of the Autism-Spectrum Quotient (AQ) in a nonclinical population sample of 6,900 typical adult males and females

Abstract

The Autism-Spectrum Quotient (AQ) is a self-report measure of autistic traits. It is frequently cited in diverse fields and has been administered to adults of at least average intelligence with autism and to nonclinical controls, as well as to clinical control groups such as those with schizophrenia, prosopagnosia, anorexia, and depression. However, there has been no empirical systematic review of the AQ since its inception in 2001. The present study reports a comprehensive systematic review of the literature to estimate a reliable mean AQ score in individuals without a diagnosis of an autism spectrum condition (ASC), in order to establish a reference norm for future studies.A systematic search of computerized databases was performed to identify studies that administered the AQ to nonclinical participant samples representing the adult male and female general population. Inclusion was based on a set of formalized criteria that evaluated the quality of the study, the usage of the AQ, and the population being assessed.After selection, 73 articles, detailing 6,934 nonclinical participants, as well as 1,963 matched clinical cases of ASC (from available cohorts within each individual study), were analyzed. Mean AQ score for the nonclinical population was 16.94 (95% CI 11.6, 20.0), while mean AQ score for the clinical population with ASC was found to be 35.19 (95% CI 27.6, 41.1). In addition, in the nonclinical population, a sex difference in autistic traits was found, although no sex difference in AQ score was seen in the clinical ASC population.These findings have implications for the study of autistic traits in the general population. Here, we confirm previous norms with more rigorous data and for the first time establish average AQ scores based on a systematic review, for populations of adult males and females with and without ASC. Finally, we advise future researchers to avoid risk of bias by carefully considering the recruitment strategy for both clinical and nonclinical groups and to demonstrate transparency by reporting recruitment methods for all participants.

Relating Attentional Biases for Stimuli Associated with Social Reward and Punishment to Autistic Traits

“…The mean and variability of this measure were similar to those reported in a meta-analysis of AQ scores in the normal population (Ruzich et al, 2015).…”

Why We Should Study the Broader Autism Phenotype in Typically Developing Populations

“…In a large meta-analysis, Ruzich, Allison, Smith, and Watson (2015) reported average scores of 35 on the AQ in people with an ASD, which is more than twice the general population's mean score of 17. Similarly, the SRS mean raw score for samples of individuals who have received an ASD diagnosis is greater than 80, while the mean raw score for typically developing participants is generally less than 40 (Constantino & Gruber, 2012).…”

“…In their meta-analysis, Ruzich et al (2015) identified more than 850 articles that reported on the AQthe measure most widely used in studies examining the associations between the BAP and performance on a number of different tasks tapping into a number of different constructs, including temperament (Pisula, Kawa, Danielewicz, & Pisula, 2015), language abilities (Whitehouse, Barry, & Bishop, 2007), sensory sensitivity (Robertson & Simmons, 2013), and visuomotor associative learning (Parkington, Clements, Landry, & Chouinard, 2015). We believe that these kinds of efforts with nonclinical samples can contribute to the study of ASD.…”

Language disorder from infancy to adulthood: predictors and outcomes

“…Studies in this area have concentrated on investigating outcomes of early language delays in terms of ASD diagnoses (Charman, Drew, Baird, & Baird, 2003), while other research has focused on the role of early language ability as antecedents of later autistic-like traits. This focus on autistic-like traits has arisen from recent research showing ASD-like features across large community samples, providing support for a continuum of autistic-like traits across the general population, with clinical ASD representing the extreme end of the distribution (Palmer, Paton, Enticott, & Hohwy, 2015;Ruzich et al, 2015). For this reason, studies have attempted to identify developmental factors associated with autistic-like traits with the overall aim of providing important insights into the mechanisms that underpin the clinical condition.…”

“…More recently, research has documented the presence of ASD-like features across large community samples, providing support for a continuum of autistic-like traits across the general population, with clinical ASD representing the extreme end of the distribution (Palmer et al, 2015;Ruzich et al, 2015). Given the prevalence of autistic-like traits in the general population, a growing body of research has attempted to identify early predictors of increased autistic symptomology in the wider population.…”