Comorbidity of Autism and Seizure Disorders

At a QSAC meeting, there arose the question of what could be the underlying causes or triggers of impulsive behaviors and cognitive impairment for individuals affected by autism and epilepsy. Is the seizure disorder worsening the autistic symptoms? How could we effectively treat the co-occurrence of these problems? These are interesting questions that I would like to invite those who read this Blog to think about.

Epilepsy is quite common in autism spectrum disorders, and it is increasingly recognized as an additional clinical problem. We evaluated the coexistence of autism and seizure disorder among the adult consumers at QSAC and found there to be a prevalence of about 30%, which correlates with studies that have reported a prevalence of 5% to 38.3% of comorbidity. These values are higher than in the normal population of children and adolescents (0.5%) (Tuchman & Rapin 2002; Clarke, et. al. 2005; Blumenfeld and Taylor, 2003).

The high prevalence of seizure disorders within autistic populations supports the notion that autism is a neurobiological disorder where the dysfunction of the nervous system is caused by genetic, metabolic, or other biological factors. Complex partial seizures and infantile spasms are probably the most common seizure types in autism and in some occasions, tuberous sclerosis. To return to the original questions, I believe that the seizure disorder is one of the risk factors that increase the cognitive impairment, adaptive and behavioral problems in individuals with autism. When autism is associated with chronic epilepsy or uncontrolled seizures this may lead to loss of neurons in the region of the hippocampus [e.g. hippocampal sclerosis]. The seizure disorder in individuals with autism may complicate the impaired cognition such as memory deficits, language impairment, visuospatial changes, decreased executive function, wandering, pacing, agitation, disruptive vocalizations, and exacerbation of repetitive behaviors. We would like to hypothesize that the comorbidity of autism and epileptic symptoms may lead to a deterioration and regression of the cognitive functions (Tharp, 2004).

Paradoxically, the impaired cognition of affected individuals could be secondary to adverse effects of antiepileptic drugs, to an underlying biological abnormality, or to the abnormal release of the cytokine protein by neurons in the hippocampus, cortex and amygdala [cytokine mediate and regulate immunity, inflammation, and hematopoiesis] (Lorenz, 2001, Jankowsky & Patterson, 1999).

This clinical treatment of affected individuals with autism and epilepsy is very complex because the efficacy of antiepileptic drugs and psychotropic medications is limited to the treatment of respectively the seizures or the specific problematic behaviors such as irritability, impulsivity, hyperactivity, repetitive behaviors, or aggression. Anticonvulsant medications could also potentially tamper with mood and behavioral disturbances frequently observed in Autism Spectrum Disorder (ASD).

The antiepileptic medications should always be adjusted against the frequency seizures episodes. Some studies argue that some individuals with autism and seizure episodes should not receive any anti-seizure medications. In some cases the management of seizure episodes has led to the minimizing of the core symptom domains of autism. In addition, some studies indicate that seizures may be part of the underlying pathophysiology of autism (Gillberg, 1991; Tuchman & Rapin 2002).

Therefore, the treatment of individuals with a comorbidity of epilepsy and autism is still obscure and clinicians should carefully evaluate the maladaptive behaviors, psychiatric symptoms, and seizure episodes, to determine the appropriate combination of medication and dosage for each affected individual (Gillberg, 1991; Tuchman, 2004; Hrdlicka, et. al., 2004).

For your viewing pleasure, I have attached below an interesting, yet - to warn you - quite long video lecture on the subject of “Seizures in children with Autism disorder” by Barry Tharp, M.D. as part of the M.I.N.D. Institute Lecture Series on Neurodevelopmental Disorders.