Although it may be surprising to some, there is a longstanding association between epilepsy and various forms of mental illness. Indeed, among patients with temporal lobe epilepsy, 70% meet diagnostic criteria for at least one form of mental illness, the most common being mood and anxiety disorders.
Although numbers vary from study to study, research suggests that between 10% and 20% of people with temporal lobe epilepsy have obsessive compulsive disorder (OCD); this is a rate that is much higher than what would be expected in the general population, where the prevalence is typically about 1.5% to 2%. While many forms of epilepsy carry an increased risk of OCD, temporal lobe epilepsy appears to have the strongest link.
What Is Epilepsy?
Before discussing the relationship between OCD and epilepsy it may be helpful to first define what epilepsy is.
Epilepsy affects about 1.5% of the population. Although there are many types of epilepsy, each involves a disruption in the communication between neurons in the brain. When normal communication between nerve cells is disrupted it can lead to a pattern of neuronal activity that is known as a seizure.
Seizures can take on many forms and can range from subtle alterations in consciousness to full blown, so-called "grand mal" seizures where consciousness is lost and the entire body goes into violent convulsions.
People with epilepsy usually experience numerous seizures and very often require treatment with medication to control seizure activity. In rare cases, brain surgery to remove certain brain regions may be necessary to control seizure activity and return quality of life.
Epilepsy has multiple risk factors, including brain injury, recent stroke, brain tumor, infection, low blood sugar, certain dementias and inherited genetic conditions.
The Link Between OCD and Epilepsy
Interestingly, it has been observed that people with temporal lobe epilepsy often display a specific pattern of behavior referred to as interictal behavior syndrome. This behavioral syndrome is often characterized by alterations in sexual behavior, increased religiosity and extensive, and in some cases compulsive, writing and drawing (sometimes called hypergraphy). Likewise, studies looking at personality variables have also identified obsessionality as a core trait of individuals with temporal lobe epilepsy.
Of course, these behaviors alone are not nearly sufficient for a diagnosis of OCD; however, they are a first clue that there is a vulnerability to engaging obsessive, repetitive behaviors among individuals with temporal lobe epilepsy.
In temporal lobe epilepsy, OCD usually occurs early after onset of seizures. Later onset of OCD symptoms in epilepsy may be tied to brain damage occurring in brain "circuits" exposed to repeated seizure activity.
From a neurobiological perspective it has been suggested that epilepsy may disturb circuits connecting different brain regions; particularly within the limbic system, basal ganglia and frontal cortex - brain regions that have been strongly implicated in the expression of OCD symptoms. Although not consistent across all studies, disruptions in the neurochemcial serotonin have also been noted in both epilepsy and OCD. Finally, although research findings are mixed, total remission of OCD symptoms has been noted after surgery to remove brain areas affected by epilepsy.
Treatment of OCD in the Context of Epilepsy
Treatment of OCD in the context of epilepsy is very similar to OCD that occurs alone. Psychological treatments such as exposure and response prevention therapy or cognitive behavior therapy are a good first choice; however, because of the difficulties in memory sometimes experienced in epilepsy, treatment may need to be adjusted accordingly.
Treatment with medication is also possible; however, because of the seizure-inducing potential of some medications used to treat OCD, such as clomipramine, some OCD medications are not indicated for use in patients with epilepsy. Others may be permissible but at carefully controlled dosages. In addition, potentially negative interactions between OCD medications and antiepileptic drugs need to be monitored. If you are seeking medical treatment for OCD, be sure to advise your family doctor or psychiatrist of all underlying medical conditions.
Studies suggest that OCD in the context of epilepsy is often grossly under-diagnosed. This is important because when OCD and epilepsy co-occur the risk of depression rises substantially. Depression makes the treatment of OCD and epilepsy more difficult, reduces treatment adherence and increases the risk of suicide.
Barry, J.J. & Huynh, N. "Psychotropic drug use in patients with epilepsy and developmental disabilities". In: Devinsky O and Westbrook LE, (eds). Epilepsy and Developmental Disabilities. Boston: Butterworth-Heinemann; 2001;205-217.
Kaplan, P.W. "Obsessive-compulsive disorder in chronic epilepsy" Epilepsy and Behavior 2011, epublished ahead of print.
Monaco, F., Cavanna, A., Magli, E., Barbagli, D., Collimedaglia, L., Cantello, R., & Mula, M. "Obsessionality, obsessive-compulsive disorder, and temporal lobe epilepsy" Epilepsy & Behavior 2005 7: 491-496.