[Epilepsy and psychiatric disorders: epidemiological data]

Abstract

Data about psychiatric disorders associated with epilepsy as well as their risk factors are heterogeneous. The overall prevalence of psychiatric disturbances in epileptic patients can be estimated between 20 and 30 per cent. It is the highest in pharmocoresistant cases seen in specialized centers. Psychotic disorders, depression, and suicide are the three most common among interictal disturbances. Psychoses affect 2 to 9 per cent of patients and are more frequent in cases with aura or altered consciousness, such as in complex partial seizures and absences. They correlate positively with the multiplicity of seizures but often inversely with their frequency. Temporal lobe epilepsy is associated with schizo phrenic-like and paranoid types of psychosis, but frontal lobe epilepsy is also common. A putative association with predominant left or bilateral EEG abnormalities in cases with partial epilepsy remains to be confirmed, as well as the frequency of underlying structural lesions. Depressive disorders affect 20 to 60 per cent of patients. While their occurrence with partial complex seizures and left hemisphere foci is common, the role of temporal lobe involvement still appears controversial. Depression prevails in cases with seizures that occasionally, albeit rarely, secondarily generalize and correlates with the duration of the disease, intractable seizures, and polypharmacy. A genetic factor is likely to play a role. Suicides rates are increased, encountered in 0.2-0.5 per cent of patients and causing deaths in 3-7 per cent of them. The overall risk might be the highest during the first years after diagnosis of epilepsy, as well as in patients with temporal lobe foci, depression, or psychosis. Great variability and discordance in results show the major difficulties encountered in epidemiologic studies. Most of these problems relate to the classification of epileptic disorders as well as that of psychiatric disorders, the variability in the methods and measures which are used, and frequent bias in the selection of patients. We review here data about the frequency of major psychiatric disorders in epileptic patients or the frequency of epileptic disorders in psychiatric patients, and also possible risk factors related to the epileptic disease and its evolution.