Common Neuropsychiatric Problems in Epilepsy

Epilepsy represents a complex neuropsychiatric condition with significant public health impact.  The prevalence estimates of active epilepsy range from about 1 to 4% of the general population.  Like other medical conditions, epilepsy appears to increase the risk for a variety of secondary (or cormorbidity problems).  Understanding these related risks can aid patients, families and clinicians in understanding symptoms, common presentation conundrums and best treatment approaches. A recent epidemiology survey published by Ottman and colleagues of a large sample of the general population in the U.S. provides insight into the range and relative risk for variety of disorders in those with epilepsy.  The key elements of this survey include the following key design items:

• Data part of Epilepsy Comorbidity and Health (EPIC) Survey
• Mail survey to random households in the United States
• Case definition of epilepsy a yes response to the following question: “Have you ever been told you have a seizure disorder or epilepsy?”.
• Those who reported being diagnosed with epilepsy (2.0% of those surveyed) were compared to those without a self-reported diagnosis
• Surveyed other neuropsychiatric, pain and other medical conditions included: anxiety disorder, depression, bipolar affective disorder, ADHD, sleep disorder/apnea, tremor/movement disorder, migraine, fibromyalgia, chronic pain, neuropathic pain, asthma, diabetes, high blood pressure
• Risk ratios controlled for a variety of potential confounding variables including: sex, age, income, population density,census region, prior head injury, and prior stroke

The comorbid conditions with the highest relative risks (that were statistically significant) are shown in the accompanying summary figure.   A prevalence ratio of 2.0 would mean those with epilepsy are twice as likely to have the diagnosis compared to controls without epilepsy. ADHD, bipolar disorder, movement disorder/tremor and fibromyalgia led the rank list of diagnoses.  A significant number of the disorders showed statistically significant associations between a risk of 1.0 to 2.0.   The only disorders that showed no link to a diagnosis of epilepsy were diabetes and high blood pressure.

The primary weaknesses of these types of studies is reliance on self-report diagnosis by a the respondents.  One way to exam the validity of diagnoses is to conduct more detailed direct interviews and examinations of a subset of study participants.  Also the rates of self-reported diagnoses can be compared to known direct interview studies.  Here are the rates of self-reported neuropsychiatric diagnoses in those without epilepsy in the current study: depression 25.6%, anxiety 13.9%, bipolar disorder 6.8%, ADHD 5.5%.   The bipolar disorder self-report rates seem unexpectedly high and the implications for the validity of this study is unclear.

The authors note their study demonstrating a lifetime self-report prevalence rate of 2.0% is consistent with previous other population-based surveys.  Neuropsychiatric comorbidities were common in those reporting epilepsy ranging from a low of 8.7% for neuropathic pain to 32.5% for depression.  The authors note this study will aid those caring for epilepsy and help target comprehensive assessment and managment.

Ottman R, Lipton RB, Ettinger AB, Cramer JA, Reed ML, Morrison A, & Wan GJ (2011). Comorbidities of epilepsy: Results from the Epilepsy Comorbidities and Health (EPIC) Survey. Epilepsia PMID: 21269285