Depression and schizophrenia in epilepsy: social and biological risk factors

BACKGROUND In a retrospective study we investigated the role of social and biological risk factors for the development of major depression and schizophreniform psychoses in epilepsy. We tested the hypotheses that social risk factors are associated with depression and biological risk factors are associated with schizophreniform psychoses. METHOD We studied 25 patients with epilepsy and paranoid-hallucinatory psychosis, 25 patients with epilepsy and major depression, and 50 non-psychiatric epilepsy patients (controls) with respect to biological and psychosocial variables. RESULTS Schizophrenic patients had an earlier age of onset of epilepsy and a more severe epilepsy as characterised by history of status epilepticus, multiple seizure types and severity of seizures compared to non-psychiatric controls. Simple seizure symptoms were often vegetative and EEGs showed various abnormalities including temporal lobe discharges but no lateralisation to either side. With respect to antiepileptic drugs (AED) there were only few significant differences between groups: Polytherapy as well as treatment with phenytoin (DPH) was more frequent in psychotic patients as compared to non-psychiatric patients. Patients with psychoses were also characterized by a disturbed familial background, lack of interpersonal relationships, social dependency and professional failure. Depressive patients were significantly older than non-psychiatric controls and they suffered more frequently from focal epilepsies arising from the temporal lobe. They did not differ from controls with respect to severity of epilepsy. Treatment with valproate (VPA) was inversely linked with depression, suggesting that VPA may have prophylactic antidepressive properties in epilepsy patients. There were no psychosocial variables significantly linked with depression. CONCLUSIONS In this study, patients with different forms of psychiatric complications in epilepsy could clearly be distinguished from controls. However, we could not confirm the simple hypothesis that there are biological predictors for schizophreniform psychoses and psychosocial predictors for major depression. Neurological and sociological variables seem linked with both, suggesting a multifactorial etiology.