Individuals with epilepsy often find subtle difficulties in different areas of cognition (i.e. cognitive impairment), such as complex attention, memory, language, and speed of thinking. Even though they are rarely very severe, they can be detected by neuropsychological testing and in many cases can have negative effects on school and work performance. There are several factors that can influence the nature and degree of any cognitive impairment.
First is whether a person has focal epilepsy, which means that seizures are arising from a specific place in the brain that often has some type of structural or functional abnormality. In that case, persons with epilepsy may exhibit problems with cognitive processes that involve the area of the brain involved in the seizures. For example, the left temporal lobe is normally involved in learning and retaining new verbal information (e.g., names, instructions). Therefore, people with seizures arising from the left temporal lobe are likely to show selective problems with verbal information. This relative weakness may sometimes become somewhat worse following surgery to remove that part of the brain.
A second source of cognitive impairment can be frequent interictal discharges, which are brief, abnormal bursts of electrical activity in the brain that occur between seizures. Interictal discharges represent very brief disruptions in normal brain communication but do not proceed to a seizure. These can disrupt ongoing brain processing and therefore acutely disrupt cognition.
Another issue is the amount and type of antiseizure medication the person may be taking. These drugs benefit people with epilepsy by reducing the probability of seizures but at a potential cost of slowing cognitive functioning in some cases. Certainly the brain does ‘adapt’ to these medications over time, but many people with epilepsy maybe taking two to four medications to control seizures and the effects of these different medications can add up.
Finally, if epilepsy occurs early in life, there can be interruptions to schooling (due to seizures and drugs) that can reduce the person’s opportunity to learn as well as their classmates. There are more severe childhood epilepsy syndromes that can often result in profound cognitive problems such as the inability to speak, dress, etc.
Despite these potential negative influences on cognition, most individuals with epilepsy are able to do well in school and in the workplace, although occasionally special accommodations need to be in place to help maximize their potential. In addition, we often note some improvements in general functioning following surgery, especially when individual are seizure-free and have their anticonvulsant medications reduced.