Autism spectrum is an umbrella term used to describe a range of
conditions characterized by difficulties in social interactions and communication,
unusual sensitivity to sensory inputs, and restricted or repetitive behaviors.
The word “spectrum” means there is a great array of symptoms with various degrees of severity.
Among people diagnosed with autism, there can be a wide range of intellectual and learning abilities,
from highly capable to severely challenged. A number of other conditions tend to occur
more often in autistic people, including gastrointestinal disorders, epilepsy,
feeding problems, anxiety and depression. People with autism are often stigmatized,
bullied, and have troubles developing a relationship or landing a job.
Autism has a remarkably high heritability but there is a role for environmental factors
including parental age, maternal infection or exposure to certain medications or toxins
before or during pregnancy, low birth weight, and extreme premature birth.
Multiple genes have been involved, many of them having a function in synaptic formation or pruning
– the processes in which connections between brain cells and brain areas are established.
Neuroimaging studies show widespread differences in an autistic brain. Notably,
there are alterations in neuronal connectivity - some connections are enhanced, while others are
reduced. Overall, though, an autistic brain seems to have more connections than usual.
There is also evidence that areas of the brain containing the so called
“mirror neurons” are different in most people with autism. “Mirror neurons” are thought
to be responsible for “mimicking” behaviors that form the basis of our ability to learn
new expressions or skills by imitating other people. For example, by seeing an adult smile,
a baby learns to smile back. Altered function of these neurons may underlie the inability
to express emotions or understand other people’s emotions in someone with autism.
Our brain has a certain limit on the amount of information it can process at one time.
A typical brain selectively focuses on some aspects of the surroundings and ignores others,
keeping sensory input at a manageable level. An autistic brain, on the other hand, seems to absorb
all information more or less equally, or in some cases, fixates on a different object or subject.
As a result, autistic people may notice details that others do not, but have difficulty following
the topic of a conversation or seeing other people’s point of view. They may take in more
information than their brain can handle and become overwhelmed. This causes stress and may affect the
ability of the brain to process the information properly, resulting in a delayed response or no
response at all. In trying to reduce sensory input, people with autism typically withdraw
from others and follow a strict daily routine. Depending on the affected sensory modalities,
some people avoid eye contact, others cover their ears to reduce noise level, wear loose clothing
to reduce touch, or eat the exact same foods day after day. Changes to a daily routine can
cause stress and upset because they bring about new and potentially overwhelming information.
Performing repetitive movements, known as stimming, is a common way to relieve stress.
A person with severe autism may be at risk of overloading their brain with too much sensory
input, causing distress, which may lead to disruptive or self-harming behaviors.
On the other hand, changes in brain wiring may also result in intellectual strengths
such as keen observation, great attention to details and excellent memory. People with autism
often have intense interest in certain specific subjects and, if receiving proper guidance
and support, may excel in a particular career. Signs of autism usually manifest early in life
and diagnosis can often be made by age 2 or 3. Early diagnosis is important as
it can help children get the support they need to overcome difficulties and develop their strength.