Acute effects of antipsychotics on healthy volunteers: An ERP study using meaningful stimuli with self-referential task and placebo controls

Poster Session B - Sunday, April 14, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Mingyi Diao¹ (mingyi.diao@mail.mcgill.ca), Ilya Demchenko¹, Aidan Schottler-Raymond¹, Jingyan Quan¹, J. Bruno Debruille¹; ¹McGill University

Antipsychotics, like risperidone, are still the mainstay of treatment for schizophrenia. Today, we know that they can improve certain clinical symptoms of patients fast, even within an hour. However, studies of their cognitive impact have not controlled for placebo effects. One work reports that antipsychotic-placebo effects decrease the amplitude of the N400 event-related brain potentials (ERPs) while increasing those of the central P2 and of the LPP (late positive potential). These two ERP increases have tentatively been related to the binding of stimulus representations with particular additional self-representations. Namely, with the temporary representations of oneself as being under the effect of a psychoactive drug. Here, to isolate the chemical effects of risperidone, we tested 47 healthy participants who received 1 mg of risperidone and 47 matched others who had a fully deceptive antipsychotic-placebo. After 90 minutes, all performed a semantic categorization task and a particular self-referential task explicitly focusing on long-term self-representations. Relative to the placebo, a further increase of the P2 and of the LPP amplitudes was found in the risperidone group in the semantic task but not in the control self-referential task. In contrast, the risperidone left N400 amplitudes unchanged. These results suggest that risperidone may have a rapid and distinctive influence on early and late binding with self-representations. Associated with a fast decrease of clinical symptoms, such acute cognitive improvements may predict the efficacy of a medication at rehabilitating a patient on the long run.

Topic Area: LANGUAGE: Semantic