P300 is considered to be a potential biological marker for schizophrenia. Most of the studies on P300 and patients with First Early Psychosis (FEP) are focused on P3b subcomponent, whereas few studies assess P3a impairments, despite the existence of differences between both P300 subcomponents. Furthermore, they are associated with different cognitive processes, thus their impairments would be related to distinct cognitive problems.

Assessing the amplitudes impairments of P3a and P3b in FEP.

Our sample was composed of 24 patients with FEP and a group of 24 controls, paired for sex and age. Event-related Potentials were registered using a 16-electrodes cap according to the international expanded 10–20 system.

Regarding P3a, we found statistically significant differences at C3 electrode site. Statistically significant differences were obtained for P3b at C3, C4 and P4 electrode sites. All amplitudes were smaller in FEP compared to controls in both P300 subcomponents.

[P3a subcomponent]

[P3b subcomponent]

Since the early stages of schizophrenia there are decreased amplitudes in P3a and P3b subcomponents. Thereby, this reflects impairments in both the redirection of the attention monitoring and the information actualization in the working memory, respectively.