Although the debate over the causes of autism is still vexed, arguments over the nature of the disorder itself rage, too. In the November 1 issue of Frontiers In Neuroscience [hat tip to Frontal Cortex for blogging it on 10/25], Henry Markram, Tania Rinaldi and Kamila Markram propose a new unifying theory. They call it “The Intense World Syndrome” and the basic idea is that the core problem in autism is not difficulty recognizing other people’s thoughts and motivations (the “theory of mind” theory), but a hyper-responsive brain that encodes most sensory input as overwhelming.
The DSM characterizes autism by three symptom domains: impairments in social behavior, communication and language problems and repetitive, limited behaviors. Oversensitivity, however, has long been recognized as key issue: people with autistic spectrum disorders are well known for hating “itchy” fabrics, loud noises, bright lights and many other imposing sensations. Even just being touched by another person can be perceived as over-stimulating.
The authors claim that it is this experience of an “intense world” that causes the other symptoms, rather than the other symptoms being results or caused by a different aspect of the same developmental problem.
From this perspective, the “theory of mind” problems are not related to an inherent inability to understand that other people have different thoughts and motivations. Instead, they result from attempts to avoid being bombarded by social stimuli that appear terrifying to them. The language and communication problems could result from difficulties patching together relevant information while being inundated by irrelevant stimuli-- and the repetitive behaviors could be viewed as attempts to self-soothe and reduce the barrage.
The researchers make their case well based on an animal model of fetal exposure to valproate-- an anti-epileptic drug that has been linked to autism in children of mothers who took it while pregnant. They note that their theory could also explain autistic savants-- the hyper-processing, when not overwhelming, could produce superior skills.
It also might make sense of the observation that many people with Asperger’s syndrome and other autistic spectrum disorders, far from being “cold” and lacking empathy for the feelings of others, often appear to be too empathetic and actually have difficulties because they often feel overwhelmed by the pain of others. Check it out… well worth a read.
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