The links between epilepsy and psychiatry have a long and respectable history, but for reasons best deliberated on by historians, the growing gap between neurology and psychiatry in the 20th century led to a considerable divergence of opinion as to the relationships between psychiatric disorders and epilepsy. Part of this confusion was due to the eventually almost exclusive psychological approach taken to neuropsychiatric disorders by psychiatrists, and the relative neglect by neurologists of behavior problems that could be associated with neurologic disorders. Further, in the field of epilepsy there was confusion over the distinction between seizures and epilepsy. Many people equated the two, but seizures as signs and causing symptoms are quite distinct from the underlying pathologic process of the epilepsy. The ongoing interictal electrophysiologic disturbances, which presumably reflect on underlying electrochemical aberrations within the brain that are easily identifiable by various imaging techniques, may be expected to lead to continuing disturbances of cerebral function. If these occur in areas of the central nervous system that have an impact on emotion and behavior, then psychiatric disturbances may be the expected outcome of at least some people with epilepsy, depending upon the site and type of the underlying epileptic discharge.

By the midpoint of the 20th century, it was a strongly held view, particularly in the United States, that people with epilepsy, if they had psychiatric difficulties, had them because of secondary factors. These included not only the stigmatization of having a terrible condition such as epilepsy, with such a poor quality of life and considerable social disadvantage (which was known to occur then and still occurs now), but also drug factors (remembering that phenobarbitone was commonly employed in those times) or, for example, cerebral trauma from head injuries following seizures. The concept that the underlying neurologic disturbance that led to the epileptic seizures could also provoke psychiatric problems was hard for many to accept.

There was, however, a slowly growing literature that emphasized not only the possible neurologic underpinnings of psychiatric disorders generally, but also the psychiatric complications of neurologic disorders, including epilepsy. From a purely anatomic point of view, the unraveling of the concept of the limbic system, from the earlier circuitry proposed by Papez to the later, more sophisticated elaborations of people such as MacLean, emphasized that within the brain there were neuronal structures and circuits that had specifically to do with modulation of emotion. This was a new idea, because before the development of the limbic system concept, there was no clear cerebral framework for an understanding of how the brain felt and expressed emotion. It was crucial to elaborating on the link between epilepsy and emotion to realize that two key limbic structures, the hippocampus and the amygdala, were frequently involved in the underlying pathology of epilepsy, particularly in the localization-related epilepsies, and newly developed techniques of recording from sites within the brain revealed that in between seizures, interictal abnormalities were recorded from such structures. More recently, the uncovering and elaboration of the direct associations between medial temporal structures and limbic forebrain structures and the unraveling of the neuroanatomy of the limbic forebrain by authors such as Heimer et al. have given clear neurologic underpinnings for an understanding of the behavioral consequences of neurologic disorders, epilepsy being no exception.¹

However, understanding the neuroanatomy in more detail is not sufficient. It is clear that people with epilepsy, like anybody else, can have a straightforward psychiatric problem. A number of these are classifiable in terms of standardized diagnostic schedules (for example DSM-VI or ICD-10) and, when present in people with epilepsy, should receive the same amount of attention for management as they would if the patient did not have epilepsy. However, the contention of the last 30 or so years has been that there are some psychiatric problems that are more intimately imbedded within the context of the underlying neurobiologic process of the epilepsy.

This underlying neurobiology of the behavior disorders is discussed at the very outset of this section. The first chapter essentially makes the point that at least some of the psychiatric presentations are potentially directly interwoven with either the ictus or the interictal neurologic changes, this underlying neurology giving a particular stamp to the clinical presentations that lead them to differ somewhat from the psychiatric presentations diagnosed in the absence of the underlying neurologic disorder.