What is autism?
Autism is a condition where there is impaired neurodevelopment to the extent that it affects communication, social interaction and intellectual development. A broad range of compromised behaviors related to abnormal brain development, are classified as autism or more correctly autism spectrum disorder (ASD). It becomes evident in childhood before the age of 3 years and persists through to adulthood. The overall cognitive functions are challenged in autistic children and the severity of symptoms determines the level of autism. Certain neurological conditions show symptoms common to autism like:
- Asperger Syndrome – show all signs of autism but have normal language development.
- Disintegrative disorder – a regressive condition where skills learned in early life are lost by the age of ten years.
Few studies suggest Rett syndrome as a form of autism but clinically, it is a completely different condition. Autistic children and adults deviate from what is considered be ‘normal human behavior’ but are often unusually gifted in certain aspects.
The exact number of children affected with autism is not clear, given the broad range of symptoms. According to a 2008 report by the U.S. Centers for Disease Control and Prevention (CDC), 1 in every 88 children, is autistic. However, recent studies reveal that autism-related disorders are rather more common.
Right from conception, the brain and spinal cord (central nervous system) starts developing in the zygote (fetus). The brain advances to a new stage of development with each passing day. Every brain area regulates an important physiological function. The timing (stage of brain development) when the distortion occurs determines the erroneous development of a specific brain region and impairment of its associated function. Faulty development of brain areas, responsible for higher cognitive functions like learning and memory or empathy, marks the prevalent cause. This altered brain structure that specifically contributes to autistic conditions can be studied with the help of neuroimaging studies like magnetic resonance imaging (MRI).
The course of brain development determines our personality, mental functioning and intellectual abilities. All of our interpersonal skills and social behavior depends on the information processing ability of the brain. Normal brain development involves acquiring correct communication skills (language and speech), learning from past experiences and retaining a memory of it, the ability to accept changes and to change accordingly and some higher functions like understanding the meaning of spoken words, unspoken emotions and interpretation of the world around us. The sequence of pathological events initiated with developmental errors exacerbates in the presence of adverse environmental factors. Overall, a variable combination of developmental (genetic) defect and environmental factors collectively contribute to a set of autism-related behavior, unique to every individual.
Although being a genetic trait, the presentation of symptoms varies from person to person. Some major causes include :
Chromosomes contain a stipulated number of genes. Each of these active genes produce a few million proteins that contribute to the normal development of body and functions. Almost all active genes are represented in the brain. Therefore, any change in the number of genes due to chromosomal addition and duplication (increased) or deletion (reduced) could lead to developmental defects in brain structure and its related function.
Nerve cells (neurons) communicate with each other at cellular junction, called a synapse. Although a void space, chemicals (neurotransmitter) are released from the activated nerve cell into the synapse, from where it is taken up by the recipient nerve cell. This relay of transmitting information from one cell to another continues across a specific subset of cells that are dedicated for specific functions. Therefore, at cellular level, synapse formation is central to normal brain functioning. However, certain genetic defects compromise the normal course of synapse formation and communication, thereby causing neurological conditions.
Teratogens and environmental factors
Exposure to toxic compounds at the time of pregnancy could cause birth defects, often presented as physical disabilities. Some potentially harmful chemicals those affect brain development include phenols, brominated chemicals and pesticides. The first 8 to 10 weeks of pregnancy are crucial for healthy brain development and its associated functions. Smoking, consumption of alcohol or drugs and taking undue stress during pregnancy increase the risk of newborns to have brain defects, including autism.
Most of the autistic symptoms start showing by the age of 18 months. While the first symptom may be the inability to focus on a specific object like a toy, other important symptoms that may only become evident later include :
- Poor communication skills – unable to correlate a word to its meaning and therefore, putting words together gets difficult.
- Conversing using gestures alone, using mumbled or no words.
- Problems in initiating and maintaining a conversation.
- Slow in picking up language skills and repeating the sentences spoken.
- Distorted perception of social signals and events in situations may lead to reclusive behavior and outbursts in an otherwise unprovocative setting.
- Avoids eye contact.
- Lack of empathy or may appear as such to others.
- Sensory perception is overtly sensitive.
- Extreme sensitivity to sensory stimuli – may react unexpectedly to otherwise normal sights, tastes, smells or touch.
- Unexplained possessiveness towards an object.
- Resists change in any schedule or a fixed pattern of activity or context.
- Low attention span except to activities of their choice and when alone.
- Motor activity – repetition of a set of body movements over and again.
- Unpredictable learning – usually learn some difficult tasks before learning simpler things. However, in most of the cases, these qualities regress and the learned tasks are forgotten with age.
Autism can be managed with appropriate therapy. Studies correlating brain development and acquisition of language skills, have suggested several language parameters to keep a check on the communication-related autistic conditions. Pediatricians should be consulted if any of the following parameters are not met :
- Babbling, gesturing (pointing and waving) by 12 months.
- Speaking single words by 16 months.
- Clearly speaking two-word phrases by 24 months.
- Continuous linguistic development with age.
Diagnostic measures include :
- Blood tests to exclude other physiological conditions.
- Questionnaire especially designed for screening autism.
Based on the extent of autistic symptoms present, the overall cognitive performance in these tests are scored in terms of Intelligence Quotient (IQ). Severe autistic patients have low IQ values.
Intensive treatment involving constructive and highly structured activities may be helpful in most cases of autism in children. Treatment is designed based on the specific requirement of every child. Autism is incurable. Most common forms of treatment are:
The use of bright visual cues or pictures and toys to capture the attention are frequently employed in structured manner to let the child get a feel of their natural environment. It teaches them to adapt themselves to the changing environment as well as develop various skills in the response to these stimuli.
Applied Behavioral Analysis
Honing specialized skills also boosts confidence and instills a positive feeling. Although being slow learners, autistic children master these skills with time. Training autistic children with specialized skills needs persistent effort and dedication. Children are trained according to their behavioral inclinations.
Speech-language therapy helps to improve their correlation of a word with its meaning and further its incorporation in making a meaningful sentence. Making speech clearly audible and rectifying pronunciation.
Medication is used to relieve neurological symptoms like mood swings, anxiety, aggression, sleep difficulty or hyperactivity. Commonly prescribed drugs are:
- Selective serotonin reuptake inhibitors (SSRIs) which dampen neuronal activity by reducing neurotransmitter (serotonin)-mediated communication. Mood stabilizers. Risperidone is the only approved SSRI for 5 to 16 year old autists.
- Methylphenidate elevates neuronal activity and is also used for treatment of attention-deficit hyperactivity disorder (ADHD).
Article reviewed by Dr. Greg. Last updated on July 3, 2012