Sex differences have been described in multiple facets of psychosis. Evidence to date concludes that men have a higher incidence (McGrath et al., 2008), and present an earlier age of onset of the disorder (Eranti et al., 2013; Häfner et al., 1993; Hui et al., 2016), whilst women tend to experience a later onset, with a secondary peak of onset after the age of 45 (Kirkbride et al., 2012). Women with psychosis generally show a better course of the disorder, better social functioning, and better treatment adherence than men (Cotton et al., 2009; Ochoa et al., 2012; Riecher-Rössler et al., 2018a). Previous research suggests that negative symptoms are more prevalent in men, while women present higher levels of affective symptoms, although the latter seem to improve over the years, so that women may no longer have this disadvantage (Thorup et al., 2014). Recently, sex differences have been reported regarding metacognitive and social cognitive correlates of clinical insight in first-episode psychosis (FEP) (Pousa et al., 2024). Sex differences have also been observed in the impairment of neurocognitive functioning, which is one of the core features of psychosis (Fatouros-Bergman et al., 2014; Ochoa et al., 2012; Riecher-Rössler et al., 2018a). Most evidence suggests that women with psychosis demonstrate superior neurocognitive function over the course of the disorder, showing better results in verbal memory and learning, attention, and executive functions such as inhibition and cognitive flexibility (Bozikas et al., 2010; Goldstein et al., 1998; Vaskinn et al., 2011; Zhang et al., 2017, 2012). However, other studies suggest that, after a long-term follow-up past the first episode, men and women with psychosis may end up exhibiting similar neurocognitive deficits (Ayesa-Arriola et al., 2020).

Neurocognitive impairments are already evident in FEP (Albus et al., 2020; Fatouros-Bergman et al., 2014; Mesholam-Gately et al., 2009), but research on sex differences in neurocognition in FEP is still inconclusive. Several studies have found that women with FEP have a better performance in verbal learning and memory (Ayesa-Arriola et al., 2014; Buck et al., 2020; Ittig et al., 2015; Pu et al., 2019; Smelror et al., 2021), while some studies report no sex differences in that regard (Danaher et al., 2018; Hui et al., 2016). Ayesa-Arriola et al. (2014) observe how men with FEP achieve better results in information processing speed, but other studies report no sex differences (Fatouros-Bergman et al., 2014; Labad et al., 2016; Pu et al., 2019). Danaher et al. (2018) note that, when including affective psychoses in the sample, women with FEP score better in processing speed. Evidence is also inconsistent in relation to working memory. There are studies showing that men with FEP perform better (Fatouros-Bergman et al., 2014), with male patients having shorter reaction times in working memory tasks (Ittig et al., 2015), but others find no differences (Ayesa-Arriola et al., 2014; Danaher et al., 2018). Regarding attention, Labad et al. (2016) find an advantage of women with FEP, while others report a similar performance in both male and female patients (Danaher et al., 2018; Fatouros-Bergman et al., 2014; Zhang et al., 2012). There seems to be some consensus on men with FEP having a better performance in visuospatial tasks, verbal comprehension, reasoning, and problem solving (Ayesa-Arriola et al., 2014; Danaher et al., 2018; Labad et al., 2016). No sex differences have been found in cognitive flexibility, verbal fluency, or inhibitory control in FEP (Ayesa-Arriola et al., 2014; Danaher et al., 2018; Ittig et al., 2015).

Exploring the effect of sex on neurocognitive functioning is a key element in understanding the prognosis of psychosis and identifying factors relevant to the disorder's course (Ventura et al., 2023). It may also elucidate the need for targeted early interventions for neurocognition in psychosis, whether for prevention or treatment planning, based on the patient's sex (Bucci et al., 2018; Tan et al., 2021). In addition, it is important to consider sociodemographic or clinical confounding factors that may affect performance on neurocognitive tasks. Exploring whether these variables have a distinct effect in men compared to women with FEP, rather than simply controlling for them, might help reveal how they interact and affect neurocognitive impairment. This, in turn, could eventually explain the existing lack of consensus regarding sex differences in neurocognition in FEP.

The present study aimed to explore sex differences in neurocognition among individuals with FEP. Based on the evidence to date, we expect to find a similar performance in cognitive flexibility and inhibitory control both in male and female patients. Given the mixed results found in previous literature, we refrain from formulating any other hypothesis regarding verbal memory and learning, attention, working memory and processing speed.