A possible association between epilepsy and psychosis was first recognized in antiquity but gained attention in the middle of the nineteenth century with the writings of Benedict Morel80 and Jules Falret.81 Hill,82 in 1953, made the first modern report of a schizophrenia-like syndrome in patients with temporal lobe epilepsy (TLE).

Interictal psychosis

Psychosis in epilepsy can occur during interictal and postictal periods. The prevalence of interictal psychosis (IIP) in epilepsy ranges from 0% to 16%, with a mean of 7–8%.83,84 Compared to schizophrenia, IIP may be associated with a greater incidence of:85,86

• empathic persecutory delusions
• auditory hallucinations
• appropriate affect
• suicidality
• lack of autistic traits

As compared to patients with only epilepsy, those with IIP have:86

• later age of onset of epilepsy
• more complex partial seizures
• more auras
• less generalized epilepsy

Some have found that seizure onset is typically 18 to 21 years before the onset of psychosis,87,88 but other evidence suggests that both sets of symptoms begin at the same time.89 Some studies show that TLE of dominant laterality is positively correlated with IIP,90,91 but other studies demonstrate a positive correlation with bitemporal foci85 or no correlation with laterality.92

Postictal psychosis

Postictal psychosis (PIP) is characterized by fluctuating combinations of symptoms:89,93

• delirium
• persecutory and other delusions
• auditory, visual, and other hallucinations
• affective changes

Postictal psychosis generally follows a lucid interval that lasts from 2 to 72 hours. Postictal confusion, on the other hand, is typically maximal immediately or shortly after a seizure or cluster of seizures.93

Some studies have found that bilateral seizure foci and clustering of seizures are significantly associated with episodes of PIP.84,93 Other studies have found that generalized seizures93 and complex partial seizures89,94 were associated with PIP.

Drug withdrawal can be temporally associated with PIP and IIP, probably by increasing seizure frequency in most cases.86,93,94

Can recurrent PIP evolve into chronic IIP? Logsdail and Toone89 found minimal evidence of progression from PIP to IIP in their patients. Alper et al., however, found that about 15% of patients with PIP went on to develop an interictal psychosis (K. Alper, personal communication).

Adapted from: Devinsky O and Tarulli A. Progressive cognitive and behavioral changes in epilepsy. In: Devinsky O and Westbrook LE, eds. Epilepsy and Developmental Disabilities. Boston: Butterworth-Heinemann; 2001;133–149.
With permission from Elsevier (www.elsevier.com).
Reviewed and revised May 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.

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