Cognitive and Psychological Side Effects of Antiepileptic Drugs

*Katja Eva Brückner*

## **Abstract**

Among well-known side effects such as dizziness, nausea, headache and diplopia medical treatment of epilepsy may cause side effects on cognition, mood and behavior. In special constellations this can profoundly affect compliance with the medication as well as quality of life. Some patients are more vulnerable to side effects than others. Side effects can have profound impact on the development and future life of a patient. Some antiepileptic drugs (e.g. topiramate, zonisamide) show a more severe side effect profile than others (e.g. lamotrigine, levetiracetam). Thus, in the treatment of epilepsy, it is crucial to consider such possible side effects – especially in the beginning of or while changing the medical treatment. Specific neuropsychological examinations can monitor side effects on cognitive functions like concentration, memory or speech function. If this is not possible in an ambulant setting, specific screening instruments and repeated and precise interviews of patients and/or relatives can help to discover potential side effects. Because most side effects can be reversible, dosage modification or drug replacement is required as soon as incompatibilities are discovered.

**Keywords:** epilepsy, antiepileptic drugs, cognitive side effects, psychological side effects

#### **1. Introduction**

As one of the most common chronic neurological disorders, epilepsy affects many people across all population groups and ages. A prevalence rate of 0.5–1% of the population has been assumed [1]. More recent studies on large cohorts report even significantly higher rates: there is evidence of a prevalence rate of 1.2% of active epilepsy in the population [2]. Active epilepsy means that people diagnosed with "epilepsy" have had a seizure within the last 12 months, have seen a doctor because of their epilepsy, and/or have been treated with anticonvulsant medication. Before starting therapy, it must be clarified whether epilepsy is actually present. 20–30% of all patients with non-epileptic seizures are incorrectly diagnosed with epilepsy [3]. Therefore, differential diagnoses - such as psychogenic non-epileptic seizures, cardiovascular fainting, sleep behavior disorders, paroxysmal movement disorders or metabolic diseases have to be excluded. A differentiation from nondisease-relevant, paroxysmally occurring phenomena that do not require therapy (e.g. sleep myoclonus) is necessary before initiating therapy.

After a precise diagnosis, clarification of possible differential diagnoses and a positive therapy decision, drug treatment is usually the first choice in the treatment of epilepsy. Drug therapy is never curative, because the selected medication only

prevents or reduces seizures in the sense of symptom prophylaxis. The underlying cause of epilepsy is not cured with drug treatment. Most patients with epilepsy can be easily being treated with medication and, depending on the epilepsy syndrome, become seizure-free with monotherapy or combination therapy [4]. Meanwhile, many agents with different mechanisms have been approved for the treatment of epilepsy. In addition to the desired effect - successful seizure control or a significant reduction of seizure frequency - as with all medications, there are also undesirable effects with anticonvulsants that are only tolerable to a certain extent and then only with a significant improvement in the seizure situation. The tolerable extent of these interference effects differs individually and depends on the individual situation. In addition to "classic" physical disturbances such as dizziness, nausea, headache and double vision, negative effects on cognitive performance and mental health are the least tolerated effects. Since drug therapy ideally leads to seizure freedom but does not cure epilepsy, in most cases drug treatment is a long-term therapy.
