Background Schizophrenia is a complex mental illness with significant sex differences. Cognitive impairment is common in patients with schizophrenia, even in remission. This study was designed to examine the sex differences in the relationship between cognitive impairment and clinical correlations with first-episode drug-naïve (FEDN) schizophrenia. Methods 93 FEDN patients (male/female = 45/48) and 160 controls (male/female = 74/86) were enrolled to compare the sex differences in cognitive functions measured by the MATRICS Consensus Cognitive Battery (MCCB). Positive and Negative Syndrome Scale (PANSS) and Hamilton Depression Scale (HAMD) were used to evaluate patients' clinical symptoms. We compared cognitive impairment with sociodemographic characteristics and measures of different genders, as well as group-by-sex interactions. Results Our results showed that male patients had significantly lower scores for symbol coding, digital sequence, and verbal learning than female patients, while the healthy controls showed similar sex differences. In female patients, multiple linear regression analysis confirmed that PANSS negative symptoms and general psychopathology scores, HAMD total score, and education level were independent contributors to MCCB total score. In male patients, only education was an independent contributor to MCCB total score. Conclusions These findings revealed significant sex differences in cognitive impairments and clinical symptoms in FEDN, which will be worthy of a follow-up study of schizophrenia in the future.

Background Schizophrenia is a complex mental illness with significant sex differences. Cognitive impairment is common in patients with schizophrenia, even in remission. This study was designed to examine the sex differences in the relationship between cognitive impairment and clinical correlations with first-episode drug-naïve (FEDN) schizophrenia. Methods 93 FEDN patients (male/female = 45/48) and 160 controls (male/female = 74/86) were enrolled to compare the sex differences in cognitive functions measure by the MATRICS Consensus Cognitive Battery (MCCB). Positive and Negative Syndrome Scale (PANSS) and Hamilton Depression Scale (HAMD) were used to evaluated patients' clinical symptoms. We compared cognitive impairment with sociodemographic characteristics and measures of different genders, as well as group-by-sex interactions. Results Our results showed that the MCCB total and index score in FEDN were lower than in the control group, except for category fluency and social cognition. Male patients had significantly lower symbol coding, digital sequence, and verbal learning scores than female patients, and the controls showed a similar sex difference. Interestingly, we also found six indexes and MCCB total score that showed diagnosis-by-sex interactions, belonging to the speed of processing, attention, working memory, and verbal learning. The MCCB total score showed correlations with PANSS total score and education for both genders. In female patients, education showed significant positive correlations with MCCB total and all ten index scores. Multiple linear regression analysis confirmed that negative symptoms and general psychopathology of PANSS, HAMD total score, and education were independent contributors to MCCB total score. In male patients, only education was an independent contributor to MCCB total score. Conclusions These findings revealed significant sex differences in cognitive impairments and clinical symptoms in FEDN. These results should be considered, which will be worthy of a follow-up study of schizophrenia in the future.

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