Autism (cont.)
What causes autism?
Since autism was first added to the psychiatric literature fifty years ago,
there have been numerous studies and theories about its cause. Researchers still
have not reached agreement regarding its specific causes. First, it must be
recognized that autism is a set of a wide variety of symptoms and may have many
causes. This concept is not unusual in medicine. For instance, the set of
symptoms that we perceive of as a "cold" can be caused by literally hundreds of
different viruses, bacteria, and even our own immune system. Autism is,
undoubtedly, a biologically-based disorder. In the past, some researchers had
suggested that autism was the result of poor attachment skills on the part of
the mother. This belief has caused a great deal of unnecessary pain and guilt on
the part of the parents of autistic children, when in fact, the inability of the
individual with autism to interact appropriately is one of the key symptoms of
this developmental disorder.
In support of a biological theory of autism,
several known neurological disorders are associated with autistic features.
Autism is one of the symptoms of these disorders. These conditions include
tuberous sclerosis (an inherited disorder), the fragile X syndrome, cerebral
dysgenesis (abnormal development of the brain),
Rett syndrome, and some of the
inborn errors of metabolism (biochemical defects). Autism, in short, seems to be
the end result or "final common pathway" of numerous disorders that affect brain
development. In general, however, when clinicians make the diagnosis of autism,
they are excluding the known causes of autistic behaviors. However, as the
knowledge of conditions that cause autism advances, fewer and fewer cases will
be thought of as being "pure" autism and more individuals will be identified as
having autism due to specific causes.
There is a strong association between autism and
seizures. This association
works in two ways: First, many patients (20% to 30%) with autism develop
seizures. Second, patients with seizures, which are probably due to other
causes, may develop autistic-like behaviors. One special and often misunderstood
association between autism and seizures is the
Landau-Kleffner Syndrome. This
syndrome is also known as acquired epileptic aphasia. Some children with
epilepsy develop a sudden loss of language skills--especially receptive language
(the ability to understand). Many often also develop the symptoms of autism.
These children often, but not always, have a characteristic pattern of
electrical brain activity seen on EEG (electroencephalogram) during deep sleep
called electrographic status epilepticus during sleep (ESES). The usual age of
onset of language loss or regression is around four years of age, which makes the
Landau-Kleffner syndrome distinguishable from autism on these grounds, in that
autism usually is first exhibited in younger children. However, in recent years,
some children (very, very few) who did not exhibit overt (observable) seizures
were found to have Landau-Kleffner syndrome.
The importance of these findings is
that, although rare, the Landau-Kleffner syndrome can resolve spontaneously and
in some cases can be treatable with prednisone, a steroid medication related to
cortisone. This association between the Landau-Kleffner syndrome and autism has
led many clinicians and families to search for the typical EEG pattern (ESES) in
autistic individuals. This unusual EEG pattern is seen only in deep sleep, which
usually requires prolonged recordings of up to 12 hours. Many, many autistic
children and adults will display some abnormalities on their sleep EEG, but
probably very few have true Landau-Kleffner syndrome that will respond to
treatment.
It must also be noted that prednisone, in the very high doses used to
treat Landau-Kleffner syndrome, almost invariably produces side effects, which
may include weight gain, high blood pressure, diabetes, growth failure, stomach
ulcers, irritability, destruction of the hip joint, and susceptibility to
infectious disease (suppressed immune system). While most of these side effects
are reversible, some of the complications of high dose prednisone therapy can be
irreversible and even fatal.
Other treatments ranging from common anticonvulsant
therapy to surgery have been proposed and are being tried for Landau-Kleffner
syndrome. It is difficult to evaluate the true effects of any treatment for
Landau-Kleffner syndrome due to the high rate of spontaneous resolution of
symptoms (remission).
Next: Is autism genetic? »
- risperidone, Risperdal - Information about the drug risperidone (Risperdal) prescribed for mania, schizophrenia, stuttering, Tourette syndrome, and OCD (obsessive compulsive disorder).
- Detecting Hearing Loss in Children - Read about tests used for identifying hearing loss in children, treatment information, causes, risk factors and signs of hearing impairment, and learn about degrees of hearing loss.
- Seizure (Epilepsy) - Learn about epilepsy, or seizure disorder. Causes include head injury, trauma, prenatal injury, poisoning, medications, stroke, heart attacks, alcoholism, infection, and more. Symptoms, diagnosis, and treatment information is included in the information.
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