Frequency and age-related variables in interictal psychoses in localization-related epilepsies

Several studies have described that patients with temporal lobe epilepsy (TLE) develop psychoses more frequently than patients with extra-temporal localization-related epilepsy (LRE). However, few controlled studies have demonstrated an increased susceptibility to psychosis in TLE patients. As one of a series of multi-center studies on psychosis in epilepsy, we investigated whether the frequency of interictal psychosis differs between types of LRE.

We reviewed some biological characteristics of 197 PE patients with interictal psychosis and of 456 LRE patients with no history of psychosis. Type of PE was determined as TLE, frontal lobe epilepsy, parietal lobe epilepsy, occipital lobe epilepsy, and multi-lobar epilepsy/undifferentiated lobar epilepsy by clinical symptoms, EEG findings, and neuroimaging. The frequency of psychosis for each type of LRE was compared. Ages at onset of epilepsy and psychosis and the time interval between onset of each were also analyzed.

There was no significant correlation between psychosis and epilepsy type (P=0.211). Age-related variables also failed to show any significant differences between LRE types (age at onset of epilepsy, P=0.369; age at onset of psychosis, P=0.852; the time interval, P=0.893).

Patients with LREs as well as with TLE are susceptible to interictal psychosis. The mean ages at onset of symptoms and the interval between onset of epilepsy and onset of psychosis that we observed suggest that patients with LREs, regardless of focus, may share similar processes in the development of psychiatric symptoms.