Psychosis in adults with epilepsy and its relationship to demographic, clinical and treatment variables.

: Psychiatric symptoms and disorders are commonly reported with epilepsy. This study aimed to determine the prevalence of interictal psychosis (IIP) in adults with epilepsy and its risk predictors. : The study included 710 patients (mean age: 36.40 years; age at onset: 13.58 years; duration of epilepsy: 22.80 years). All underwent neurological and psychiatric interviewing, electroencephalography and brain imaging. : IIP was reported in 20.65%, of them 50% had temporal lobe epilepsy with impaired awareness and/or to bilateral tonic clonic, 42.47% had frontal lobe epilepsy with impaired awareness and/or to bilateral tonic clonic and 7.53% had generalized tonic-clonic seizures. Compared to patients without psychosis, patients with psychosis were older at age of examination, had earlier age at onset, frequent seizures, longer duration of epilepsy and long-term antiepileptic drugs therapy and many relatives with epilepsy. Nearly 76.71% had history of postictal psychosis (PIP). The mean age of onset of IIP was 30.45 years and its mean duration was 3.84 months. Approximately 22% of patients with IIP had family history of psychosis. Patients developed IIP 10 years or more after epilepsy onset. Multivariate logistic regression analyses showed that predictors for IIP were the age at onset and duration of epilepsy, number of seizures, family history of epilepsy or psychosis, history of PIP and different types of epilepsy. : IIP is not infrequent with chronic epilepsy regardless to its type. These findings emphasize the importance of optimizing patients' treatment and early recognition and management of IIP. IIP: interictal psychosis; PIP: post-ictal psychosis; TLE: temporal lobe epilepsy; FLE: frontal lobe epilepsy; GTC: generalized tonic clonic; AEDs: antiepileptic drugs; CBZ: carbamazepine; VPA: valproate; LEV: levetiracetam; APDs: antipsychotic drugs.