New test facilitates diagnosis of autism in adults

Autism Spectrum Disorder is a collective term that embraces autism and Asperger's Syndrome. The disorder causes major problems in communicating and interacting with other people, and can lead to compulsive routines and interests. In adults, distinguishing Autism Spectrum Disorder from other psychiatric conditions can be a problem, as their symptoms often overlap or are similar to those in schizophrenia, attention deficit and hyperactivity disorder (ADHD) or severe personality disorders.

The screening methods used today for making a correct diagnosis are time-consuming and require considerable expertise. Research specialists at the Department of Clinical Neuroscience have, under the leadership of Dr Susanne Bejerot, refined and simplified an existing American test, RAADS-R (Ritvo Autism and Asperger Diagnostic Scale-Revised). The new test is a questionnaire with 14 self-screening questions. It is therefore known as RAADS-14 Screen. The scale includes three sub-scales that measure mentalisation difficulties, social anxiety and sensory oversensitivity -- all common symptoms in autism. The answers are categorised on the basis of whether the symptoms appeared in childhood or developed later in life.

The newly presented evaluation included 135 adults of normal intelligence with Autism Spectrum Disorder and 508 control subjects with some form of psychiatric disorder but not ASD. 590 healthy control subjects were also included in the study. The results showed that it is possible to clearly differentiate the autism spectrum group from patients with ADHD or schizophrenia, for example. The median value in the test for Autism Spectrum Disorder sufferers was 32 points (out of a total of 42), compared with 15 for ADHD patients, 11 for those other psychiatric disorders and 3 for healthy control subjects. By drawing a line at 14 points, 97 percent of the participants with Autism Spectrum Disorder could be identified.

"The problem with most psychiatric screening tools is that they have only been tested against healthy control subjects, which is completely meaningless in this context. In this case we have presented a scale which can help differentiate the autism spectrum group from other psychiatric disorders," says Dr Bejerot.

Hopefully the new test will save time and simplify the work in health care, but it could also be used in register-based research. Dr Bejerot maintains that the first five questions in the RAADS-14 Screen should be sufficient to provide a clear indication about whether Autism Spectrum Disorder can be suspected.

"Even those who normally have great difficulty in filling out forms, can usually handle answering five questions," she says.