Sex differences in association between clinical correlates and cognitive impairment in patients with chronic schizophrenia

Anticholinergic load: A commonly neglected and preventable risk to cognition during schizophrenia treatment?

Background

Cognitive impairment is a widespread feature of schizophrenia, affecting nearly 80 % of patients. Prior research has linked the anticholinergic burden of psychiatric medications to these cognitive deficits. However, the impact of the anticholinergic burden from medications for physical morbidity remains underexplored. This study aimed to evaluate the anticholinergic burden of psychiatric and physical medications in patients with schizophrenia and assess its impact on cognitive function.

Methods

A total of 178 patients with schizophrenia were recruited. The assessments included an ad hoc questionnaire for collecting demographic and clinical data. Anticholinergic burden was evaluated using the cumulative Drug Burden Index (cDBI) for each participant, and cognitive function was assessed using MATRICS. Psychopathology was measured using the PANSS, CDSS, CAINS, and the CGI-S. Statistical analysis included Student's t-tests, ANOVA, Pearson correlations, and multiple linear regressions.

Results

The average cDBI was 1.3 (SD = 0.9). The model developed explained 40.80 % of the variance. The variable with the greatest weight was the cDBI (B = -11.148, p = 0.010). Negative-expression (B = -2.740, p = 0.011) and negative-experiential (B = -1.175, p = 0.030) symptoms were also associated with lower global cognitive score. However, more years of education (B = 5.140, p < 0.001) and cigarettes per day (B = 1.331, p < 0.001) predicted a better global cognitive score.

Conclusion

This study identified specific predictors of global cognition in schizophrenia, with anticholinergic burden emerging as the strongest factor. Our findings underscore the importance of considering the anticholinergic burden of treatments, in addition to negative symptoms, when designing interventions to optimize or maintain cognitive function in patients with schizophrenia.

Sex-specific associations of plasma neutrophil gelatinase-associated lipocalin (NGAL) with cognition in patients with drug-naïve schizophrenia

This present study aimed to investigate the sex-specific association of plasma neutrophil gelatinase-associated lipocalin (NGAL) with cognition in drug-naïve schizophrenia patients for the first time. A total of 204 participants in this study, including 137 drug-naïve schizophrenia (DNS) patients and 67 healthy controls (HCs). All participants completed the Measurements and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB), and were collected fasting venous blood for NGAL measurement. DNS patients also complete the Positive and Negative Syndrome Scale (PANSS). Partial correlation analysis and multiple linear regression were used to explore sex-specific associations between NGAL and cognition. All dimensions of MCCB scores were significantly lower in both male and female DNS patients than HCs. Sex differences were significant in cognitive performance in both DNS patients and HCs. Female DNS patients experienced poorer working memory and reason& problem solving than male patients. Female HCs performed a better attention/vigilance and visual learning, a poorer reason& problem solving than male HCs. In patients with DNS, NGAL levels were negatively associated with positive subscale of PANSS and positively associated with working memory and visual learning only in female. However, there was no significant correlation between NGAL levels and all cognitive tests in both male and female HCs. Regression model showed that higher level of NGAL was an independent protective factor for cognitive performance in female patients with DNS, whereas there was no such role in male patients. Our findings suggest sex specificity between NGAL levels and cognitive performance in DNS patients.

Gender differences in cognitive improvements after two months of atypical antipsychotic treatment in first episode schizophrenia

Aims

This study aims to explore the gender differences in cognitive improvements after two months of atypical antipsychotic treatment in first episode schizophrenia (FES).

Methods

82 patients with FES, including 50 male patients and 32 female patients, were enrolled in the present study. Positive and Negative Syndrome Scale (PANSS) and MATRICS Consensus Cognitive Battery (MCCB) were respectively conducted to evaluate the clinical symptoms and cognitive function of patients with FES at baseline and after treatment. Repeated measure ANOVA was performed to compare gender differences in cognitive domains scores between baseline and 2-month follow-up. Stepwise liner regression model was performed to explore the effect factors of cognitive improvements in patients.

Results

There was no significant difference in age of onset, education years, PANSS scores, duration of untreated psychosis and Olanzapine equivalent doses between male and female patients (all p > 0.05). In the comparisons of cognition function, male patients exhibited better performance in social cognition compared with female patients at baseline (t = 3.20, p < 0.05). After treatment, improvements of attention/vigilance and working memory were both found in male patients and female patients (attention/vigilance, F = 11.867, p < 0.05; working memory, F = 18.265, p < 0.05). In addition, improvement of speed of information processing was only found in female patients (F = 11.65, p < 0.01). Significant interaction between time and gender was found in speed information of processing (F = 4.140, p = 0.045). Stepwise liner regression model revealed that improvements of negative symptoms promote improvements of cognitive function in female patients (all p < 0.05).

Conclusions

Our findings revealed gender differences of cognitive improvements in patients with FES after 2-month treatment. It provides new evidence for gender differences in cognitive symptoms of schizophrenia, and also provides preliminary clues for further individualized cognitive intervention strategies.

Use of the Chinese version of the MATRICS Consensus Cognitive Battery to assess cognitive functioning in individuals with high risk for psychosis, first-episode schizophrenia and chronic schizophrenia: a systematic review and meta-analysis

More than one hundred studies have used the mainland Chinese version of the MATRICS Consensus Cognitive Battery (MCCB) to assess cognition in schizophrenia, but the results of these studies, the quality of the reports, and the strength of the evidence provided in the reports have not been systematically assessed. We identified 114 studies from English-language and Chinese-language databases that used the Chinese MCCB to assess cognition in combined samples of 7394 healthy controls (HC), 392 individuals with clinical high risk for psychosis (CHR-P), 4922 with first-episode schizophrenia (FES), 1549 with chronic schizophrenia (CS), and 2925 with schizophrenia of unspecified duration. The mean difference (MD) of the composite MCCB T-score (-13.72) and T-scores of each of the seven cognitive domains assessed by MCCB (-14.27 to -7.92) were significantly lower in individuals with schizophrenia than in controls. Meta-analysis identified significantly greater cognitive impairment in FES and CS than in CHR-P in six of the seven domains and significantly greater impairment in CS than FES in the reasoning and problem-solving domain (i.e., executive functioning). The only significant covariate of overall cognitive functioning in individuals with schizophrenia was a negative association with the severity of psychotic symptoms. These results confirm the construct validity of the mainland Chinese version of MCCB. However, there were significant limitations in the strength of the evidence provided about CHR-P (small pooled sample sizes) and the social cognition domain (inconsistency of results across studies), and the quality of many reports (particularly those published in Chinese) was rated 'poor' due to failure to report sample size calculations, matching procedures or methods of handling missing data. Moreover, almost all studies were cross-sectional studies limited to persons under 60 with at least nine years of education, so longitudinal studies of under-educated, older individuals with schizophrenia are needed.

Variations of plasma oxidative stress levels in male patients with chronic schizophrenia. Correlations with psychopathology and matrix metalloproteinase-9: a case-control study

BACKGROUND

Accumulating evidence has indicated that oxidative stress (OS) and matrix metalloproteinase-9 (MMP-9) may contribute to the mechanism of schizophrenia. In the present study, we aimed to evaluate the associations of OS parameters and MMP-9 levels with psychopathological symptoms in male chronic schizophrenia patients.

METHODS

This study was an observational, cross-sectional, retrospective case-control study. Plasma hydrogen peroxide (H2O2), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), serum matrix metalloproteinase-9 (MMP-9), and tissue inhibitors of metalloproteinases-1 (TIMP-1) levels were assayed in 80 male patients with chronic schizophrenia and 80 matched healthy controls. Schizophrenia symptoms were assessed by the Positive and Negative Syndrome Scale (PANSS). Multivariate regression was used to analyze relationships between OS parameters and MMP-9, and clinical symptoms.

RESULTS

Our results demonstrated that levels of antioxidant enzymes, SOD, GSH-Px, H2O2, and MDA were significantly decreased, whereas CAT and MMP-9 levels were increased in patients with schizophrenia, when compared with healthy controls (all P < 0.05). In schizophrenia patients, correlation analyses showed that H2O2 levels were significantly and positively correlated with PANSS positive scores, CAT and MDA levels were significant negatively correlated with PANSS negative scores and PANSS total scores, and MDA levels were significantly positively correlated with MMP-9 levels (all P < 0.05). However, we did not find that MMP-9 played an interaction role between OS parameters and PANSS total scores and subscales scores (all P > 0.05).

CONCLUSIONS

Our results showed that alterations of plasma OS parameters in male patients with chronic schizophrenia were associated with psychopathology and MMP-9, suggesting that OS and neuroinflammation may play important role in the mechanism of schizophrenia.

Alterations of serum neuropeptide levels and their relationship to cognitive impairment and psychopathology in male patients with chronic schizophrenia

Serum neuropeptide levels may be linked to schizophrenia (SCZ) pathogenesis. This study aims to examine the relation between five serum neuropeptide levels and the cognition of patients with treatment-resistant schizophrenia (TRS), chronic stable schizophrenia (CSS), and in healthy controls (HC). Three groups were assessed: 29 TRS and 48 CSS patients who were hospitalized in regional psychiatric hospitals, and 53 HC. After the above participants were enrolled, we examined the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and the blood serum levels of α-melanocyte stimulating hormone (α-MSH), β-endorphin (BE), neurotensin (NT), oxytocin (OT) and substance.P (S.P). Psychiatric symptoms in patients with SCZ were assessed with the Positive and Negative Syndrome Scale. SCZ patients performed worse than HC in total score and all subscales of the RBANS. The levels of the above five serum neuropeptides were significantly higher in SCZ than in HC. The levels of OT and S.P were significantly higher in CSS than in TRS patients. The α-MSH levels in TRS patients were significantly and negatively correlated with the language scores of RBANS. However, the BE and NT levels in CSS patients were significantly and positively correlated with the visuospatial/constructional scores of RBANS. Moreover, the interaction effect of NT and BE levels was positively associated with the visuospatial/constructional scores of RBANS. Therefore, abnormally increased serum neuropeptide levels may be associated with the physiology of SCZ, and may cause cognitive impairment and psychiatric symptoms, especially in patients with TRS.

Sex difference in association between cognitive and P50 deficits in patients with chronic schizophrenia

A large number of studies have reported that sensory gating disorders represented by P50 inhibition may be involved in the pathophysiological process of schizophrenia. However, few studies have explored the relationship between sensory gating disorders and cognitive dysfunction in patients with schizophrenia. This study aimed to explore sex differences in the relationship between cognitive and P50 deficits in patients with chronic schizophrenia, which has not been reported. A total of 183 chronic schizophrenia patients (128 males and 55 females) and 166 healthy controls (76 males and 90 females) participated in this study. The MATRICS Consensus Cognitive Battery (MCCB) was measured for cognitive function and P50 components for the sensory gating in all participants. The Positive and Negative Syndrome Scales (PANSS) was used to assess the psychopathological symptoms in patients. Female patients performed significantly better than male patients in several cognitive domains of MCCB (all p < 0.01). There were no significant differences in P50 components between male and female patients (all p > 0.05). Further analysis showed that in female patients, latency of S2 was negatively correlated with reasoning and problem-solving domain of MCCB (p < 0.05), and P50 ratio was negatively correlated with social cognition domain of MCCB (p < 0.05). In male patients, there was no any correlation between P50 and cognitive domains of MCCB. Our results suggest that there is a sex difference in the association between P50 deficiency and cognitive impairment in Chinese Han patients with schizophrenia.

Differences in olfactory dysfunction and its relationship with cognitive function in schizophrenia patients with and without auditory verbal hallucinations

Olfactory discrimination dysfunction has been observed in patients with schizophrenia (SCZ), but its relationship with cognitive function has not been clarified. The purpose of this study was to examine the differences in olfactory identification function in SCZ patients with and without auditory verbal hallucinations (AVHs) and its relationship with cognitive function. Olfactory identification function was measured in 80 SCZ patients with AVHs, 57 SCZ patients without AVHs, and 87 healthy controls (HC). Clinical symptom scores and neuropsychological measures were also administered to all corresponding subjects. Compared to HC, SCZ patients showed significant deficits in olfactory identification and cognitive function, but there were no differences in olfactory identification dysfunction and cognitive dysfunction between the two subgroups. In the non-AVHs subgroup only, poorer Olfactory Stick Identification Test for Japanese (OSIT-J) scores were significantly and positively correlated with total and delayed recall (Bonferroni correction, p < 0.002). Stepwise regression analysis revealed that factors affecting olfactory identification impairment differed in the two SCZ patient subgroups. In conclusion, this study highlights the commonality of olfactory identification dysfunction in SCZ patients and the importance of olfactory assessment of different subtypes of SCZ patients.

Sex difference in association between tardive dyskinesia and cognitive deficits in patients with chronic schizophrenia

BACKGROUND

Tardive dyskinesia (TD), a side effect due to long-term use of antipsychotic medication, is associated with cognitive impairment. Several studies have found sex differences in cognitive impairment in schizophrenia patients, while whether there are sex differences in cognitive performance in schizophrenia patients with TD has not been reported.

METHODS

A total of 496 schizophrenia inpatients and 362 healthy controls were recruited for this study. We used the Positive and Negative Syndrome Scale (PANSS) to assess patients' psychopathological symptoms and the Abnormal Involuntary Movement Scale (AIMS) to assess the severity of TD. Cognitive function was measured in 313 of these inpatients and 310 of healthy controls using the Repeatable Battery for Assessment of Neuropsychological Status (RBANS).

RESULTS

Patients with schizophrenia performed worse in all cognitive domains than healthy controls(all p < 0.001). Compared to patients without TD, patients with TD had higher PANSS total, PANSS negative symptom subscale and AIMS scores (all p < 0.001), while RBANS total, visuospatial/constructional and attention subscale scores were significantly lower (all p < 0.05). In addition, the visuospatial/constructional and attention indices remained significantly lower in male patients with TD than those without TD (both p < 0.05), but these results were not observed in female patients. Moreover, visuospatial/constructional and attention indices were negatively correlated with total AIMS scores only in male patients (both p < 0.05).

CONCLUSION

Our results suggest that there may be sex differences in cognitive impairment in schizophrenia patients with comorbid TD, indicating that female gender may have a protective effect on cognitive impairment in schizophrenia patients caused by TD.

Sex and gender differences in clinical and functional indices in subjects with schizophrenia and healthy controls: Data from the baseline and 4-year follow-up studies of the Italian Network for Research on Psychoses

Gender differences in clinical and psychosocial aspects of schizophrenia have been widely reported. Findings have not always been consistent, and some of them need further research. In a large sample of community dwelling persons with schizophrenia, we investigated gender differences in clinical, cognitive and functional indices, as well as their changes over a 4-year follow-up and their impact on real-life functioning. Gender differences in personal resources, cognitive and functional indices were explored also in a sample of healthy controls. Men with respect to women had an earlier age of illness onset, a worse premorbid adjustment in the academic domain, more severe avolition, expressive deficit and positive symptoms, lower prevalence of comorbidity for affective disorders, less frequent use of two coping strategies ('religion' and 'use of emotional support') and more frequent positive history of substance and alcohol abuse. In addition, men were more impaired in verbal learning, while women in reasoning/problem solving. Some patterns of gender differences observed in healthy controls were not confirmed in patients. Men's disadvantages in the clinical picture did not translate into a worse outcome. This finding may be related to the complex interplay of several factors acting as predictors or mediators of outcome.

Catalase and interleukin-6 serum elevation in a prediction of treatment-resistance in male schizophrenia patients

BACKGROUND

Oxidative stress (OS) and neuroinflammatory pathways play an important role in the pathophysiology of schizophrenia. The present study investigated the relationship between OS, inflammatory cytokines, and clinical features in male patients with treatment-resistant schizophrenia (TRS).

METHOD

We measured plasma OS parameters, including manganese-superoxide dismutase (Mn-SOD), copper/zinc-containing SOD (CuZn-SOD), total-SOD (T-SOD), malondialdehyde (MDA), catalase (CAT), and glutathione peroxidase (GSH-Px); and serum inflammatory cytokines, including interleukin (IL)- 1α, IL-6, tumor necrosis factor-alpha (TNF-α), and interferon (IFN)-γ, from 80 male patients with chronic schizophrenia (31 had TRS and 49 had chronic stable schizophrenia (CSS)), and 42 healthy controls. The severity of psychotic symptoms was evaluated using the Positive and Negative Syndrome Scale (PANSS).

RESULTS

Compared with healthy controls, plasma Mn-SOD, CuZn-SOD, T-SOD, GSH-Px, and MDA levels were significantly lower, while CAT and serum IL-6 levels were higher in both TRS and CSS male patients (all P < 0.05). Significant differences in the activities of CAT (F = 6.068, P = 0.016) and IL-6 levels (F = 6.876, P = 0.011) were observed between TRS and CSS male patients after analysis of covariance. Moreover, a significant positive correlation was found between IL-6 levels and PANSS general psychopathology subscores (r = 0.485, P = 0.006) and between CAT activity and PANSS total scores (r = 0.409, P = 0.022) in TRS male patients. CAT and IL-6 levels were predictors for TRS. Additionally, in chronic schizophrenia patients, a significant positive correlation was observed between IL-6 and GSH-Px (r = 0.292, P = 0.012), and the interaction effect of IL-6 and GSH-Px was positively associated with PANSS general psychopathology scores (r = 0.287, P = 0.014).

CONCLUSION

This preliminary study indicated that variations in OS and inflammatory cytokines may be involved in psychopathology for patients with chronic schizophrenia, especially in male patients with TRS.

Latent structure of cognitive tests is invariant in men and women with schizophrenia

Studies comparing the cognitive functioning of men and women with schizophrenia have produced conflicting results which could arise from sex-based differences in the latent structure of cognitive abilities. The current study used multigroup confirmatory factor analysis to examine invariance in latent structure of cognitive abilities to between men and women with schizophrenia. Confirmatory factor analysis of an initial neurocognitive assessment (men n = 612, women n = 201) and cross-validation using second assessment (men n = 549, women n = 198) demonstrated that a bifactor seven-factor model fit the data best for both men and women. Invariance analyses further indicated this model was invariant across men and women at both assessments. Group comparisons indicated women had significantly higher scores for Semantic Memory, Verbal Memory, and General Cognitive factors, whereas men exhibited better performance on the Vigilance factor. Results indicate that cognition in SZ is characterized by both a general cognitive factor and specific domains for both men and women. Invariance analysis provides evidence that cognitive differences between men and women do not result from sex-based differences in the latent structure of cognitive abilities. Current results also indicate small but statistically significant neurocognitive differences between men and women with schizophrenia.

Sex Differences in Cognition in Schizophrenia: What We Know and What We Do Not Know

Cognitive impairment is a core feature of schizophrenia. This selective review examines whether schizophrenia patients show preserved sexual dimorphism in cognition. Existing studies using performance tasks largely show comparable sex effects between schizophrenia patients and healthy populations. This pattern appears to be similar across multiple cognitive domains and across phase of illness. Our selective review also identifies several unresolved questions about sex differences in cognition in schizophrenia. A better understanding of sex differences in cognition in schizophrenia may provide important clues to probing the relationship between cognitive impairment and pathophysiological processes of the disorder.

From Memories of Past Experiences to Present Motivation? A Meta-analysis on the Association Between Episodic Memory and Negative Symptoms in People With Psychosis

Based on findings from cognitive science, it has been theorized that the reductions in motivation and goal-directed behavior in people with psychosis could stem from impaired episodic memory. In the current meta-analysis, we investigated this putative functional link between episodic memory deficits and negative symptoms. We hypothesized that episodic memory deficits in psychosis would be related to negative symptoms in general but would be more strongly related to amotivation than to reduced expressivity. We included 103 eligible studies (13,622 participants) in the analyses. Results revealed significant, moderate negative associations of episodic memory with negative symptoms in general (k = 103; r = -.23; z = -13.40; P ≤ .001; 95% CI [-.26; -.20]), with amotivation (k = 16; r = -.18; z = -6.6; P ≤ .001; 95% CI [-.23; -.13]) and with reduced expressivity (k = 15; r = -.18; z = -3.30; P ≤.001; 95% CI[-.29; -.07]). These associations were not moderated by sociodemographic characteristics, positive symptoms, depression, antipsychotic medication or type of negative symptom scale. Although these findings provide sound evidence for the association between episodic memory deficits and amotivation, the rather small magnitude and the unspecific pattern of this relationship also indicate that episodic memory deficits are unlikely to be the only factor relevant to amotivation. This implicates that future research should investigate episodic memory in conjunction with other factors that could account for the association of episodic memory deficits and amotivation in psychosis.

Stratification by Sex and Hormone Level When Contrasting Men and Women in Schizophrenia Trials Will Improve Personalized Treatment

BACKGROUND

Sex and gender differences have been reported in the prevalence, expression, treatment response, and outcome of schizophrenia, but most reports are based on relatively small samples that have not been stratified for the impact of sex hormone levels. This literature review aims to show how women's hormone levels can impact the results of male/female comparisons.

METHODS

This is a narrative review of data from publications of the last decade.

RESULTS

Epidemiologic evidence, reports of the impact of hormones on cognition, results of sexually dimorphic responses to treatment, and male/female trajectories of illness over time all suggest that female hormone fluctuations exert major effects on male/female differences in schizophrenia.

CONCLUSIONS

Information on hormonal status in women participants is rarely available in clinical studies in schizophrenia, which makes male/female comparisons largely uninterpretable. These are the current challenges. Opportunities for individualized treatment are growing, however, and will undoubtedly result in improved outcomes for both women and men in the future.

Advanced glycation end products and cognitive impairment in schizophrenia

Advanced glycation end products play a key role in the pathophysiology of schizophrenia. Cognitive impairment is one of the central features of schizophrenia; however, the association between advanced glycation end products and cognitive impairment remains unknown. This study investigated whether advanced glycation end products affect the cognitive domain in patients with schizophrenia. A total of 58 patients with chronic schizophrenia were included in this cross-sectional study. Plasma advanced glycation end products were measured using high-performance liquid chromatography (HPLC). Neuropsychological and cognitive functions were assessed using the Wechsler Adult Intelligence Scale, Third Version, and the Wisconsin Card Sorting Test Keio-FS version. Multiple regression analysis adjusted for age, sex, body mass index, educational years, daily dose of antipsychotics, and psychotic symptoms revealed that processing speed was significantly associated with plasma pentosidine, a representative advanced glycation end product (standardized β = -0.425; p = 0.009). Processing speed is the cognitive domain affected by advanced glycation end products. Considering preceding evidence that impaired processing speed is related to poor functional outcome, interventions targeted at reducing advanced glycation end products may contribute to promoting recovery of patients with schizophrenia as well as cognitive function improvement.

Sex differences in the association between symptom profiles and cognitive functioning in patients with depressive disorder

OBJECTIVE

Depressive disorder (DD) is a heterogeneous disease with sex differences in symptom profiles and cognitive performance. However, sex differences in cognitive dysfunction associated with different symptom profiles have received little systematic study. This study aimed to explore the association between clinical symptoms and cognitive deficits in patients with DD.

METHODS

A cohort of 222 hospitalized patients with DD (males/females = 114/108) and 173 healthy controls (males/females = 80/93) were enrolled. Cognitive function was measured using a comprehensive neuropsychological battery. Depression was assessed using the 17-item Hamilton Rating Scale for Depression (HAMD-17). According to different genders, the relationship between symptom profiles and cognitive deficits was identified using partial correlation analysis and multiple regression analysis.

RESULTS

Patients with DD performed significantly worse than healthy controls in all cognitive domains investigated (all p < 0.05). Remarkably, female patients scored better than male patients on information processing speed (p < 0.05). Multivariate regression analyses showed that the retardation factor score was independently associated with attention and cognitive flexibility, and the sleep disturbance factor score was independently associated with information processing speed in male patients. Furthermore, the anxiety/somatization factor score was independently associated with working memory in female patients.

CONCLUSION

In the present study, we showed that significant sex differences in the association between symptom profiles and cognitive impairment are present in DD patients. Understanding how DD patients' clinical features and cognitive performance are linked from a sex perspective may have clinical implications for predicting and interfering with the outcome of depression.

Gender Differences in Clinical and Psychosocial Features Among Persons With Schizophrenia: A Mini Review

An extensive literature regarding gender differences relevant to several aspects of schizophrenia is nowadays available. It includes some robust findings as well as some inconsistencies. In the present review, we summarize the literature on gender differences in schizophrenia relevant to clinical and social outcome as well as their determinants, focusing on clinical variables, while gender differences on biological factors which may have an impact on the outcome of the disorder were not included herewith. Consistent findings include, in male with respect to female patients, an earlier age of illness onset limited to early- and middle-onset schizophrenia, a worse premorbid functioning, a greater severity of negative symptoms, a lower severity of affective symptoms and a higher rate of comorbid alcohol/substance abuse. Discrepant findings have been reported on gender differences in positive symptoms and in social and non-social cognition, as well as in functional outcome and rates of recovery. In fact, despite the overall finding of a more severe clinical picture in males, this does not seem to translate into a worse outcome. From the recent literature emerges that, although some findings on gender differences in schizophrenia are consistent, there are still aspects of clinical and functional outcome which need clarification by means of further studies taking into account several methodological issues.