Autism and Epilepsy
(Part I of an ongoing series about the link between epilepsy and other disorders)
Jennifer Li
Definition
Autism is a lifelong developmental disability which typically emerges in the first three years of life, as a result of a neurological disorder that affects the functioning of the brain.
Autism is sometimes referred to as autism spectrum disorders (ASDs), because the symptoms of autism can present themselves in many different combinations, with different degrees of severity.
Prevalence
Prevalence of autism is about 2 to 6 in every 1000 children (8). It is associated with a relatively high rate of epilepsy. Recent studies suggest that about 7.6% of children with autism had developed epilepsy, and 5% of children had "autistic" features (2). Furthermore, approximately 25-30% may develop seizures at some point in life (4).
In half of the autistic-epileptic cases, non-febrile (non-feverish) seizures commence in the first 3 years of life; and often the rest develop seizures during puberty (1).
- Autism is 4 times more prevalent in boys than in girls (4). Furthermore, its occurrence does not have any racial or ethnic boundaries.
- Recent epidemiology studies have shown that ASDs are 10 times more prevalent than they were 10 years ago. Currently, the growth rate of autism is 10-17% per year (8).
- Autism is the second most common developmental disability, after mental retardation (10). In a recent prevalence study conducted by the CDC (Centers for Disease Control and Prevention), it has been confirmed that autism is not a rare disorder.
Cause
Although no one has pinpointed a specific cause for autism, many experts in this field believe that the root of the problem is biological or neurological differences in the brain, which in turn may be explained on a genetic basis. At this time, no single gene has been directly linked to autism. Researchers believe that the genetic explanation of ASDs may involve several genes in combination, which implies a highly complex genetic origin of the disorder (4).
One common misconception is that autism is caused by bad parenting. Such an understanding was disproved decades ago, and so far no known psychological factors in the development of the child have been shown to cause autism. Therefore, autism is not a mental illness, where the child simply misbehaves (4).
In addition, many associations between autism and epilepsy also suggest an underlying neurodevelopment disorder within the limbic system (2).
Seizures
- Autistic children with no previous seizures may develop epilepsy at time around puberty (2).
- The most common types of epileptic seizures that occur in autism are complex partial seizures, generalized tonic-clonic seizures, and combinations of seizures of various kinds (1).
- Epilepsy is more frequently reported in cases of autism that are associated with severe mental retardation (prevalence is 65-85% in autism). However, it is not a rare phenomenon in individuals with low normal intelligence (1).
Diagnosis
Signs of autism usually become visible in the very early stage of life. However, a formal diagnosis is typically made when the child exhibits a clear delay in language development, which normally could be detected at the age of 2 or 3 (9). Symptoms of autism sometimes vary, which makes an accurate diagnosis difficult and challenging. There is currently no blood test or diagnostic scan to rely on, thus the only possible way to identify autism is through observation of the patient's behaviour, with the aid of parents and other family members.
According to the National Alliance for Autism Research (NAAR), there exist warning signs that could suggest a need of immediate autism evaluation for the child (9):
- The child has not babbled or cooed by one year
- The child has not gestured, pointed or waved by one year
- The child has not spoken a single word by 16 months
- The child has not spoken two-word phrase by two years
- Experiences any loss of any language skills at any age
- Experiences with speech loss
Early Diagnosis is extremely important. The earlier a child's autistic symptoms are recognized, the more effective education and treatment can be provided.
Children with early-onset epilepsy often miss a diagnosis of autism, because specialists sometimes feel that classical autistic symptoms shown by them were to be expected only in early-onset epilepsy and so would not require any further diagnosis (1). Another difficult situation is that many antiepileptic drugs (AEDs) appear to contribute to the enhancement of autism symptoms. In addition, some autism diagnostic criteria are very similar, if not identical, to other types of clinical seizure activities.
Although the detection of autism could be difficult, several screening instruments have been developed as aids in diagnosing autism. They include 1) CARS (Childhood Autism Rating Scale) rating system; 2) CHAT (Checklist for Autism in Toddlers); 3) Autism Screening Questionnaire; and 4) Screening Test for Autism in Two-Year Olds (8).
Electroencephalogram (EEG) is also often used in differential diagnosis. However, the examination could be difficult to carry out in a child with severe behaviour problems. Nonetheless, sleep EEG could sometimes provide essential help for the successful diagnosis of autism(1).
References:
(1) Engel, Jerome Jr., Pedley, Timothy A.; Epilepsy: A Comprehensive Textbook; Lippincott-Raven Puslishers: 1997, Philadelphia; P. 2131-2132
(2) Syndromes/Autism and Epilepsy; Retrieved May 23, 2003, from British Epilepsy Association;
(3) Autism Checklist; Retrieved May 21, 2003, from Autism Society of America;
(4) Autism Spectrum Disorders (A Brief Overview); Retrieved May 23, 2003, from Autism Society Ontario;
(5) Rett's Disorder; Retrieved May 27, 2003, from Autism Society America/Oakland County Chapter;
(6) Child Disintegrative Disorder; Retrieved May 27, 2003, from Autism Society America/Oakland County Chapter;
(7) Autism Resource – Glossary of Terms; Retrieved May 23, 2003, from Coriell Institute of Medical Research;
(8) All About Autism; Retrieved May 20, 2003, from Autism Society of America;
(9) What is Autism? – Symptoms; Retrieved May 26, 2003, from National Alliance for Autism Research;
(10) What is Autism? – History; Retrieved May 26, 2003, from National Alliance for Autism Research;
Next Issue: Epilepsy & cerebral palsy
