Neuropsychiatric morbidity in focal epilepsy

Background Previous work has identified elevated prevalence rates for psychiatric disorders in individuals with medically refractory focal epilepsy, particularly temporal lobe epilepsy. Many studies were undertaken before the advent of video electroencephalogram monitoring (VEM) and magnetic resonance imaging (MRI). Aims To investigate which characteristics of the focal epilepsy syndromes are associated with the presence of depression or psychosis. Method Three hundred and nineteen individuals with focal epilepsy admitted for VEM were seen over an 11-year period. The lifetime history of depression and psychosis, epileptic site, laterality and type of lesion were determined by clinical assessment, VEM and MRI scan. Results There was a significant association between the prevalence of depressive symptoms and non-lesional focal epilepsy. There were no significant differences in prevalence of neuropsychiatric disorders between the groups with temporal lobe epilepsy and those with extratemporal lobe epilepsy. Conclusions These findings contrast with previous findings in smaller cohorts. The association between non-lesional focal epilepsy and depression may be due to the effects of a more diffuse epileptogenic area.