Monday January 26 2015
Connections in the autistic brain may be 'scrambled' in some way
"The brains of people diagnosed with autism are 'uniquely synchronised'," the Mail Online reports.
Researchers used brain scans to study the brain activity of people with high-functioning autism spectrum disorders (ASD), and found distinct and differing patterns of connectivity in adults with high-functioning ASD compared with adults who do not have the condition.
This headline is based on a study comparing resting functional magnetic resonance imaging (fMRI) scans in 141 people with or without high-functioning ASD.
High-functioning ASD tends to be the term used when people have the characteristic features of autism, such as difficulties with social interaction, but without the intellectual impairment that is classically seen.
The study found communication between different areas of the brain at rest in people with high-functioning ASD differs from that of adults without ASD. In some areas, there is more communication going on, and in other areas there is less.
The exact patterns of communication differed between different people with high-functioning ASD, and people with more differences seemed to have higher levels of ASD symptoms.
We cannot say whether these differences are the cause or a result of ASD, as all of the individuals already had the condition at the time of the brain scan.
It is not yet clear whether this finding will help with diagnosing ASD earlier, as the study did not test this.
Where did the story come from?
The study was carried out by researchers from the Weizmann Institute of Science in Israel and Carnegie Mellon University in the US.
It was funded by an Israeli Presidential Bursary, the Simons Foundation, the Pennsylvania Department of Health, the European Union, the Israel Science Foundation, Israeli Centers of Research Excellence, and the Helen and Martin Kimmel award.
The study was published in the peer-reviewed journal, Nature Neuroscience.
It isn't possible to say whether the Mail Online's suggestion that the findings "may help earlier diagnosis" will be the case.
What kind of research was this?
This was a cross-sectional study comparing the brains of adults with high-functioning ASD and adults without ASD.
ASD is the term used for developmental conditions characterised by difficulties with social interaction (such as difficulties in picking up on the emotions of others), communication (such as problems holding a conversation), and having a restricted or repetitive collection of interests or set routines and rituals.
Individuals with typical autism tend to have these features in addition to some degree of intellectual impairment.
Individuals with high-functioning autism or Asperger's syndrome tend to have normal or enhanced intellectual ability.
When we are at rest, our brains still send signals (messages) within each half (hemisphere) of the brain, and between the hemispheres.
In the past, there have been suggestions people with ASD have less signalling (communication) going on between different parts of the brain at rest than people without ASD.
However, recent studies suggest the opposite might be true. The researchers in this study wanted to resolve this by looking at more information on brain activity in people with high-functioning ASD, and those without ASD.
The design of this study is appropriate for comparing brain signalling in people with high-functioning ASD and without ASD. However, it cannot say whether these differences are the cause or a result of the ASD.
What did the research involve?
The researchers used a database of resting brain scans from adults with high-functioning ASD and adults without ASD. They compared the level of communication going on between and within the hemispheres, and in more specific regions of the brain, to see if there were any differences.
The resting brain scans were obtained using fMRI. The scans were from the Autism Brain Imaging Data Exchange (ABIDE) database, which stores resting fMRI brain scans of people with ASD and controls (people without ASD) for research purposes.
The data used in the current study was collected at a range of US universities. For some individuals, the data available also included measures of IQ and the individuals' behavioural symptoms, using the Autism Diagnostic Observation Schedule (ADOS) for symptoms in adulthood, and the Autism Diagnostic Interview (ADI) for childhood history of ASD.
The study only included people classified as having high-functioning ASD according to these scales.
The individuals whose data was analysed had an average age of around 26 years, and were mostly male (91% of those with ASD and 81% of those without).
There were 141 people in the main brain connection analyses (68 with ASD and 73 without), but not all had all of the information available on symptoms, for example.
What were the basic results?
The researchers found there was greater communication between some regions of the brain in adults with high-functioning ASD than those without ASD, but less communication between others.
This essentially meant those with high-functioning ASD showed a different pattern of resting communication in their brain from the typical pattern seen in people without ASD.
This pattern also showed differences between different individuals with high-functioning ASD – so not all people with this diagnosis had the same pattern of brain signalling at rest.
The researchers found the more the communication between the reciprocal areas in the two halves of the brain differed from the "typical" pattern, the more severe behavioural symptoms the person with ASD tended to have as an adult, using the ADOS scale (total scores).
The brain differences did not appear to be related to measures of childhood history of ASD (ADI scores) or IQ scores.
How did the researchers interpret the results?
The researchers say their findings suggest there are different spatial patterns in the connection patterns seen in the brains of people with high-functioning ASD at rest, in comparison with people who do not have the condition.
They say these connection differences could be used to measure brain differences and symptom severity in people with ASD. They also explain why previous studies have conflicting findings about the amount of signalling in the brains of people with ASD.
This study suggests resting brain communication in people with high-functioning ASD differs from that of adults without ASD. In some areas, there is more communication going on, and in other areas there is less.
In addition, the exact pattern of communication differs between different people with high-functioning ASD.
This may explain why different studies of brain activity in people with ASD have had different findings in the past. The level of differences also seems to be related to the level of symptoms a person has.
The researchers say more research is needed to see whether the resting brain connection differences seen in people with high-functioning ASD represent the extreme end of a range of differences seen in the general population.
This is particularly important, as only a relatively small number of controls were assessed, and this may not capture the full range of brain communication across people without ASD.
The researchers note they could not control for differences across the sites where data was collected – for example, how the data was compiled.
However, they say the robustness of their findings is supported by how the potential differences distorted the patterns of connections across the different sites in the brain scans of people with high-functioning ASD.
They also only used data from adults with high-functioning ASD and processed the data using the same techniques to try to reduce variability.
It's important to note we cannot say whether these differences are the cause or a result of the ASD. The results are also only applicable to adults with high-functioning ASD, and may not apply to children or people with ASD who are not in the "high-functioning" category.
At the moment, we don't know whether this information could help make a diagnosis of ASD earlier, as this study did not look at this. More studies would be needed to determine whether this is the case.
Despite being a relatively common condition, affecting around 1 in 100 people, the cause(s) of ASD remain unclear. It is thought several complex genetic and environmental factors are involved.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.