Epilepsy: A model for understanding psychosis?

Psychosis is the third most common psychiatric comorbidity in epilepsy with an estimated pooled prevalence of 5.6%. The epilepsy psychoses are classified according to their chronological link with seizures: interictal, ictal, post-ictal, alternative (forced normalisation). We are therefore in a paradoxical situation where both an excess of seizures (post-ictal psychosis) and the cessation of seizures (forced normalisation) can generate acute psychotic episodes. Different hypotheses, not mutually exclusive, can explain these two a priori antagonistic pictures of psychosis in epilepsy: (1) the neuro-oscillatory hypothesis: unusual neuronal activity would produce a remote desynchronisation of cortical networks, disturbing sensory inputs and leading to the emergence of psychotic symptoms that resolve when these unusual neuronal oscillations disappear; (2) the Dopaminergic hypothesis: the release of Dopamine in connection with the recrudescence of seizures would induce psychotic symptoms or conversely induce both the cessation of seizures and the production of psychotic symptoms in the model of forced normalisation and (3) the cerebral perfusion hypothesis: the hypoperfusion of certain cerebral regions would lead to their functional disorganisation and the post-ictal psychosis would be the expression of a prolonged psychiatric Todt phenomenon. Epilepsy may therefore represent an "experimental model" for a better understanding of the physiopathological mechanisms underlying psychosis. (c) 2023 l'Academie nationale de medecine. Published by Elsevier Masson SAS. All rights reserved.