Psychologists from Cardiff University have developed the first self-assessment test designed to help clinicians diagnose autism in adults.
Published in the Journal of Autism and Developmental Disorders the test measures the extent to which adults are affected by repetitive behaviours - one of the criteria used to diagnose autism.
These behaviours include common habits and routines, such as lining up objects or arranging them in patterns, fiddling obsessively with objects, or insisting that aspects of a daily routine remain exactly the same.
Researchers say that the test is a reliable method of measuring these behaviours to indicate when they are unusually frequent or severe.
To determine how reliable this adult self-assessment is, autism experts at Cardiff University and La Trobe University, Melbourne, trialled the test on British and Australian adults (311 participants in total) with and without an autism diagnosis.
While adults without an autism diagnosis showed a high tendency for repetitive behaviours the individuals with an autism diagnosis consistently scored significantly higher on this measure.
Autism is found in more than 1 in 100 of the population. It is hoped that the test will contribute to improvements in the diagnosis of autism.
"Many measures used for research and diagnoses of autism rely on parents, teachers or caregivers to report the behaviours of individuals with the condition," said Professor Sue Leekam, Cardiff University's Chair of Autism and Director of the Wales Autism Research Centre.
"What our research has done is develop a test where individuals can report on their own behaviours, for both research and clinical purposes, ensuring we get a fuller picture of the way that these behaviours affect people," she added.
Repetitive behaviours are not just common in autism, they are also a symptom associated with Obsessive-Compulsive Disorder (OCD), Parkinson's disease and Tourette syndrome.
The test on its own cannot diagnose autism because repetitive behaviours are common to other conditions and because repetitive behaviours are only one criterion for a diagnosis of autism. The test has been designed to help clinicians in the diagnostic process.
What is remarkable is that increased behaviours normally assessed in infancy can also be measured in a self-report form in adulthood.
The next phase of the research will be to trial the test on people of all ages with autism before implementing its use in clinics across the UK.