Epilepsy and cognition - A bidirectional relationship?

Cognitive comorbidities are very common in epilepsy and often seen as secondary to epilepsy or caused by epilepsy. The implicit and sometimes explicit assumption is that epilepsy (i.e. having seizures) damages the brain and thus leads to functional deterioration and behavioral alterations. This article highlights the historical background surrounding this viewpoint which is characterized by old reports on 'epileptic dementia' and the fact that most cognitive research in chronic epilepsies is done retrospectively. The central question of the present article is whether there is a bidirectional relationship between epilepsy and cognition. In this regard it is essential to disentangle what is the disease and what is the symptom. Cognitive problems often exist from the onset of epilepsy, if not before, and the impact of epilepsy on cognition cannot be discerned without also considering the underlying brain pathology and its dynamics. Unraveling the etiologies of epilepsy increasingly reveals conditions wherein epilepsy, cognitive and behavioral problems are all symptoms of a common underlying pathological condition. Functional reserve capacities determine the outcome of epilepsy and its treatment. A functional interrelationship exists between epilepsy and behavior, since epileptic activity can affect behavior and behavior can alter epileptic activity. In conclusion, an epilepsy-centric unidirectional view of the behavioral problems being caused by epilepsy is obsolete. Such a view may even prevent the search for and treatment of the underlying etiological factors. Instead a practical clinical approach is favored according to which the comorbidities of epilepsy must be diagnosed at the onset of the disease, and according to which comorbidities may require separate treatment approaches.