Over the last few decades there has been great progress in understanding why people on the autism spectrum think and behave in ways which are different from ‘neurotypical’ individuals (those without autism).
Back in the 1980’s Simon Baron-Cohen, Uta Frith and colleagues carried out elegant psychological tests which showed that people with autism tend to have great difficulty in ‘putting themselves in another person’s shoes’. This inability to understand other people’s thoughts and feelings, also known as theory of mind impairment, could very well explain why people with autism have such difficulty with social communication and with making friends.
Theory of mind difficulties could also help to explain why many people with autism have difficulty with metaphors and other ‘non-literal’ language. When someone says ‘I am running to stand on the same spot’ most people understand that this simply means that the person is extremely busy. Similarly, expressions such as ‘I’m over the moon’ or ‘It’s raining cats and dogs’ are not intended to be taken literally. But a person on the autism spectrum, who has difficulty in reading the intentions that lie behind other peoples’ utterances, may find such expressions, which they try to interpret literally, really puzzling or disconcerting.
Another fruitful line of research has shown that people with autism may have difficulty in keeping to a particular task, in shifting flexibly from one task to another, or in thinking up ideas for new activities. This cluster of difficulties, known as executive function problems, are not unique to autism, but may help to explain why people on the autism spectrum tend to repeat the same actions over and over again, are unusually stuck in their routines and may become very anxious about anything that is new or unfamiliar to them.
A third line of research has shown that people on the autism spectrum often have a very good eye for detail, coupled with difficulty in ‘seeing the wood for the trees’, that is in filtering out information which is not relevant to what they are doing. This thinking style, known as weak central coherence could help to explain why people on the autism spectrum may pursue unusual special interests, in which they come to acquire a great deal of knowledge and skill in one very specialised area.
A wide range of research studies suggest that these characteristic differences in thinking processes between people with autism and others are accompanied by subtle differences in the structure and functioning of the brain in people with autism.
Using brain imaging to study the structure of the brain in autism, scientists have discovered that certain key brain structures may have a slightly different size or shape in people with autism, compared with those without autism.
Moreover, using brain imaging to monitor brain activity while a person is performing particular experimental tests, scientists have shown that the activity of certain brain regions and circuits differs between people with autism and neurotypical individuals. For instance, research suggests that somewhat different patterns of brain activity are seen in people with autism compared with people without autism when they are engaged in a task identifying what a person in a photograph is thinking or feeling.
Other studies of the brain focus on a much greater level of detail- at the level of nerve cells and other microscopic components of the nervous system. This work relies on the painstaking analysis of post-mortem brain tissue which has been donated for research.
One promising idea gleaned from these different research approaches is that there may be differences between autistic and non-autistic individuals in the way areas of the brain are connected together. These so-called differences in 'wiring' could affect the facility with which signals can pass within and between different brain areas.
However, studies of brain atypicalities in autism are not conclusive because the findings don’t occur in all studies, or apply to all individuals on the autism spectrum. More work is needed!
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