Tuberous Sclerosis

Date First Published: April 2, 2007
Date Last Updated: November 22, 2010

Tuberous sclerosis is one of the conditions known to frequently co-occur with autism.^1,2  It is a genetic disorder caused by mutations in one of two genes, and causes benign tumors and lesions to form in many different organs of the body, including the brain, skin, eyes, heart, kidneys, and lungs. ¹   The impact it has on those who have it is extremely variable. Some are so mildly affected, they go undiagnosed. Others suffer severe impairments which may include seizures, mental retardation…and autism.

The frequency of autism among those who have tuberous sclerosis (TS) is about 25% --a number that increases to 44% if you include in your tally not only individuals with classic autism, but those with any pervasive developmental disorder. ³   Looking at it from the other direction – not at how many people with TS have autism, but at how many people with autism have TS -- it has been claimed that TS is found in .4 to 2.8% of those with autism. ²

Mental retardation or the presence of seizures increases the risk that a person with TS will also have autism. ³   In addition, the presence of tuberous growths in the temporal lobe has been associated with autism, especially when accompanied by any type of epileptic activity during the earliest stages of development. This suggests that “there is a critical early stage of brain maturation during which temporal lobe epilepsy perturbs the development of brain systems that underpin ‘social intelligence’ and possibly other cognitive skills, thereby inducing an autism spectrum disorder.” ⁴  In fact, it has been shown that controlling infantile spasms or other epileptic activity is associated with significant improvement in cognition and behavior for children with TS,⁵ and is crucial to insure the best neurodevelopmental outcome possible. ⁶

Because its genetic cause is clear, and its impact on the brain is at least partly understood, tuberous sclerosis provides a “unique neurogenetic model” for testing theories about what may be occurring in the brain in autism spectrum disorders. ⁴

References

1. Filipek, P.A. (2005). Medical aspects of autism. In F. Volkmar et al. (Eds.), Handbook of Autism and Pervasive Developmental Disorders (pp.534-578). Hoboken, NJ: John Wiley & Sons. (pg. 543)
2. Volkmar, F.R., Wiesner, L.A., & Westphal, A. (2006). Healthcare issues for children on the autism spectrum. Current Opinion in Psychiatry, 19, 361-366.  Abstract
3. Smalley, S.L. (1998). Autism and tuberous sclerosis. Journal of Autism and Developmental Disorders, 28(5), 407-414.  Abstract
4. Bolton, P.F., Park, R.J., Higgins, N.P., Griffiths, P.D., & Pickles, A. (2002). Neuro-epileptic determinants of autism spectrum disorders in tuberous sclerosis complex. Brain, 125, 1247-1255. (pg. 1247)  Abstract
5. Jambaque, I., Chiron, C., Dumas, C., Mumford, J, & Dulac, O. (2000). Mental and behavioural outcome of infantile epilepsy treated by vigabatrin in tuberous sclerosis patients. Epilepsy Research, 38, 151-160.  Abstract
6. Zafeiriou, D.I., Ververi, A., & Vargiami E. (2006). Childhood autism and associated comorbidities. Brain & Development, in press, doi:10.1016/j.braindev.2006.09.03 – available on-line 11/7/06.  Abstract