Sex difference in cognitive response to antipsychotic treatment in first episode schizophrenia

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.

Association Between Metabolic Risk Factors and Cognitive Impairment in Schizophrenia Based on Sex

OBJECTIVE

Sex differences have been observed in many aspects of schizophrenia, including cognitive deficits. Despite extensive research into the relationship between metabolic factors and cognitive deficits in schizophrenia, few studies have explored the potential sex difference in their association.

METHODS

We recruited 358 schizophrenia patients and 231 healthy controls. The participants underwent measurements of body mass index (BMI), waist circumference, blood pressure, triglycerides, high-density lipoprotein cholesterol, and fasting blood glucose. Metabolic risk factors included abdominal obesity, hypertension, hyperglycemia, and dyslipidemia. A collection of these metabolic risk factors has been defined as metabolic syndrome. These diagnoses were based on the criteria of the National Cholesterol Education Program's Adult Treatment Panel III. Cognitive performance was measured using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). A descriptive analysis, difference analysis, and linear regression model were used to identify the metabolic risk factors for cognitive function in schizophrenia.

RESULTS

Our findings revealed sex differences in the rate of abdominal obesity and hypertension in schizophrenic patients. Additionally, we observed sex differences in the association between metabolic risk factors and cognitive impairment in schizophrenia. Specifically, hyperglycemia was associated with the immediate memory index score of RBANS in male patients, while dyslipidemia was associated with language, attention, delayed memory index scores, and RBANS total score in female patients.

CONCLUSION

Our results suggest that sex should be considered when evaluating the impact of metabolic disorders on the cognitive function of schizophrenic patients. Moreover, our study identifies hyperglycemia and dyslipidemia as potential targets for precise treatment by sex stratification, which could benefit the improvement of cognitive impairment in schizophrenic patients.

Emerging epigenetic dynamics in gut-microglia brain axis: experimental and clinical implications for accelerated brain aging in schizophrenia

Brain aging, which involves a progressive loss of neuronal functions, has been reported to be premature in probands affected by schizophrenia (SCZ). Evidence shows that SCZ and accelerated aging are linked to changes in epigenetic clocks. Recent cross-sectional magnetic resonance imaging analyses have uncovered reduced brain reserves and connectivity in patients with SCZ compared to typically aging individuals. These data may indicate early abnormalities of neuronal function following cyto-architectural alterations in SCZ. The current mechanistic knowledge on brain aging, epigenetic changes, and their neuropsychiatric disease association remains incomplete. With this review, we explore and summarize evidence that the dynamics of gut-resident bacteria can modulate molecular brain function and contribute to age-related neurodegenerative disorders. It is known that environmental factors such as mode of birth, dietary habits, stress, pollution, and infections can modulate the microbiota system to regulate intrinsic neuronal activity and brain reserves through the vagus nerve and enteric nervous system. Microbiota-derived molecules can trigger continuous activation of the microglial sensome, groups of receptors and proteins that permit microglia to remodel the brain neurochemistry based on complex environmental activities. This remodeling causes aberrant brain plasticity as early as fetal developmental stages, and after the onset of first-episode psychosis. In the central nervous system, microglia, the resident immune surveillance cells, are involved in neurogenesis, phagocytosis of synapses and neurological dysfunction. Here, we review recent emerging experimental and clinical evidence regarding the gut-brain microglia axis involvement in SCZ pathology and etiology, the hypothesis of brain reserve and accelerated aging induced by dietary habits, stress, pollution, infections, and other factors. We also include in our review the possibilities and consequences of gut dysbiosis activities on microglial function and dysfunction, together with the effects of antipsychotics on the gut microbiome: therapeutic and adverse effects, role of fecal microbiota transplant and psychobiotics on microglial sensomes, brain reserves and SCZ-derived accelerated aging. We end the review with suggestions that may be applicable to the clinical setting. For example, we propose that psychobiotics might contribute to antipsychotic-induced therapeutic benefits or adverse effects, as well as reduce the aging process through the gut-brain microglia axis. Overall, we hope that this review will help increase the understanding of SCZ pathogenesis as related to chronobiology and the gut microbiome, as well as reveal new concepts that will serve as novel treatment targets for SCZ.

Modeling the interplay of age at onset and sex on cognition in Schizophrenia

Cognition remains one of the most critical features of the schizophrenia. A wide range of factors has been associated to neurocognition and, among these, sex and age of onset are two of the most consistently reported to influence the functional and cognitive outcome. This work aims to evaluate the effects of sex and age of onset and their interaction on cognition in 419 subjects with schizophrenia. Analyses of variance and analyses of covariance were performed to evaluate the effect of sex and age at onset on cognition. To model the possible interaction sex-onset on cognition, a separate slope regression analysis was performed. Analyses of variance showed significant differences between sexes for age and age at onset, both significantly higher among females, as well as for Executive Functions, with higher performance among males. When compared according to age at onset, late-onset patients performed better than both early- and intermediate-onset ones in Verbal Memory subtest, with a significant effect of length of illness. Moreover, early-onset patients showed a significantly lower IQ compared to both intermediate and late-onset ones, with no significant effect of length of illness. Finally, the separate slope regression revealed a significant interaction between sex and age at onset, with early-onset being associated to a worse global cognition only among male patients. Our finding of a significant sex-onset interaction effect on neurocognition sheds new light on the complex issue of cognitive heterogeneity in schizophrenia. Our data may help towards the development of personalized programs for preventive and rehabilitative purposes.

Sex-Related Differences in Pharmacological Response to CNS Drugs: A Narrative Review

In the last decades, both animal and human studies have neglected female subjects with the aim of evading a theorized intricacy of feminine hormonal status. However, clinical experience proves that pharmacological response may vary between the two sexes since pathophysiological dissimilarities between men and women significantly influence the pharmacokinetics and pharmacodynamics of drugs. Sex-related differences in central nervous system (CNS) medication are particularly challenging to assess due to the complexity of disease manifestation, drugs’ intricate mechanisms of action, and lack of trustworthy means of evaluating the clinical response to medication. Although many studies showed contrary results, it appears to be a general tendency towards a certain sex-related difference in each pharmacological class. Broadly, opioids seem to produce better analgesia in women especially when they are administered for a prolonged period of time. On the other hand, respiratory and gastrointestinal adverse drug reactions (ADRs) following morphine therapy are more prevalent among female patients. Regarding antidepressants, studies suggest that males might respond better to tricyclic antidepressants (TCAs), whereas females prefer selective serotonin reuptake inhibitors (SSRI), probably due to their tolerance to particular ADRs. In general, studies missed spotting any significant sex-related differences in the therapeutic effect of antiepileptic drugs (AED), but ADRs have sex variations in conjunction with sex hormones’ metabolism. On the subject of antipsychotic therapy, women appear to have a superior response to this pharmacological class, although there are also studies claiming the opposite. However, it seems that reported sex-related differences regarding ADRs are steadier: women are more at risk of developing various side effects, such as metabolic dysfunctions, cardiovascular disorders, and hyperprolactinemia. Taking all of the above into account, it seems that response to CNS drugs might be occasionally influenced by sex as a biological variable. Nonetheless, although for each pharmacological class, studies generally converge to a certain pattern, opposite outcomes are standing in the way of a clear consensus. Hence, the fact that so many studies are yielding conflicting results emphasizes once again the need to address sex-related differences in pharmacological response to drugs.

Polygenic Risk for Schizophrenia Has Sex-Specific Effects on Brain Activity during Memory Processing in Healthy Individuals

Genetic risk for schizophrenia has a negative impact on memory and other cognitive abilities in unaffected individuals, and it was recently shown that this effect is specific to males. Using functional MRI, we investigated the effect of a polygenic risk score (PRS) for schizophrenia on brain activation during working memory and episodic memory in 351 unaffected participants (167 males and 184 females, 25–95 years), and specifically tested if any effect of PRS on brain activation is sex-specific. Schizophrenia PRS was significantly associated with decreased brain activation in the left dorsolateral prefrontal cortex (DLPFC) during working-memory manipulation and in the bilateral superior parietal lobule (SPL) during episodic-memory encoding and retrieval. A significant interaction effect between sex and PRS was seen in the bilateral SPL during episodic-memory encoding and retrieval, and sex-stratified analyses showed that the effect of PRS on SPL activation was male-specific. These results confirm previous findings of DLPFC inefficiency in schizophrenia, and highlight the SPL as another important genetic intermediate phenotype of the disease. The observed sex differences suggest that the previously shown male-specific effect of schizophrenia PRS on cognition translates into an additional corresponding effect on brain functioning.

Sex differences in P50 inhibition defects with psychopathology and cognition in patients with first-episode schizophrenia

BACKGROUND

A large number of studies have shown that the pathophysiology of schizophrenia may be involved in sensory gating that appears to be P50 inhibition. However, few studies have investigated the relationship between clinical symptoms, cognitive impairment and sensory gating disorders in patients with first-episode schizophrenia. The purpose of this study was to explore the sex differences in the relationship between clinical symptoms, cognitive impairment and P50 inhibition defects in patients with first-episode schizophrenia, which has not been reported.

METHODS

130 patients with first-episode schizophrenia (53 males and 77 females) and 189 healthy controls (87 males and 102 females) participated in the study. Positive and Negative Syndrome Scale (PANSS) was used to evaluate the patients' psychopathological symptoms, and the 64-channel electroencephalogram (EEG) system was used to record the P50 inhibition.

RESULTS

Male patients had higher PANSS negative symptom, general psychopathology, cognitive factor and total scores than female patients (all p < 0.01). The S1 amplitude was smaller in male than female patients (all p < 0.05). Multiple regression analysis showed that in male patients, S1 latency was contributor to negative symptoms, while S1 latency, S2 latency, age, and smoking status were contributors to cognitive factor (all p < 0.05). In female patients, no P50 component was found to be an independent contributor to PANSS scores (all p > 0.05).

CONCLUSIONS

Our results indicate that there is a sex difference in the relationship between clinical symptoms, cognitive impairment and P50 inhibition defects in Chinese Han patients with first-episode schizophrenia.

Sex-specific effects of polygenic risk for schizophrenia on lifespan cognitive functioning in healthy individuals

Polygenic risk for schizophrenia has been associated with lower cognitive ability and age-related cognitive change in healthy individuals. Despite well-established neuropsychological sex differences in schizophrenia patients, genetic studies on sex differences in schizophrenia in relation to cognitive phenotypes are scarce. Here, we investigated whether the effect of a polygenic risk score (PRS) for schizophrenia on childhood, midlife, and late-life cognitive function in healthy individuals is modified by sex, and if PRS is linked to accelerated cognitive decline. Using a longitudinal data set from healthy individuals aged 25-100 years (N = 1459) spanning a 25-year period, we found that PRS was associated with lower cognitive ability (episodic memory, semantic memory, visuospatial ability), but not with accelerated cognitive decline. A significant interaction effect between sex and PRS was seen on cognitive task performance, and sex-stratified analyses showed that the effect of PRS was male-specific. In a sub-sample, we observed a male-specific effect of the PRS on school performance at age 12 (N = 496). Our findings of sex-specific effects of schizophrenia genetics on cognitive functioning across the lifespan indicate that the effects of underlying disease genetics on cognitive functioning is dependent on biological processes that differ between the sexes.

Sex differences in the association between serum BDNF and cognitive impairment in schizophrenia patients using various antipsychotics

BACKGROUND

Cognitive impairment is one of the core symptoms of schizophrenia patients. There are often various differences in the efficacy of different antipsychotics in the treatment of cognitive impairment by sex. The purpose of this study was to explore whether there are gender differences in the association between serum BDNF levels and cognitive performance in patients with schizophrenia taking different antipsychotics.

METHODS

We used Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) to assess the cognitive function of three groups of schizophrenia patients (420 on clozapine, 183 on risperidone, 215 on typical antipsychotic drugs) and 467 healthy controls. Positive and Negative Syndrome Scale (PANSS) was used to assess schizophrenia symptoms of patients. Enzyme-Linked ImmunoSorbent Assay was used to measure serum brain-derived neurotrophic factor (BDNF) levels.

RESULTS

Among the patients taking clozapine and typical antipsychotic drugs, the RBANS total score, immediate memory, attention, and delayed memory subscores in females were higher than those in males (all p < 0.05). The RBANS total score and the delayed memory subscores in female patients taking risperidone were higher than those in male patients (all p < 0.05). Significant correlation between BDNF and cognition only existed in male patients taking clozapine, male patients taking risperidone, and male and female patients taking typical antipsychotic drugs (all p < 0.05).

CONCLUSION

Regardless of antipsychotic effect, the cognitive function of female patients is better compared to that of male patients. For male patients, the association between BDNF and cognitive performance exists in each medication group. For female patients, this significant association was only shown in the typical antipsychotic group, but not in the clozapine and risperidone groups.

Characterizing the Complexity of Weighted Networks via Graph Embedding and Point Pattern Analysis

We propose a new metric to characterize the complexity of weighted complex networks. Weighted complex networks represent a highly organized interactive process, for example, co-varying returns between stocks (financial networks) and coordination between brain regions (brain connectivity networks). Although network entropy methods have been developed for binary networks, the measurement of non-randomness and complexity for large weighted networks remains challenging. We develop a new analytical framework to measure the complexity of a weighted network via graph embedding and point pattern analysis techniques in order to address this unmet need. We first perform graph embedding to project all nodes of the weighted adjacency matrix to a low dimensional vector space. Next, we analyze the point distribution pattern in the projected space, and measure its deviation from the complete spatial randomness. We evaluate our method via extensive simulation studies and find that our method can sensitively detect the difference of complexity and is robust to noise. Last, we apply the approach to a functional magnetic resonance imaging study and compare the complexity metrics of functional brain connectivity networks from 124 patients with schizophrenia and 103 healthy controls. The results show that the brain circuitry is more organized in healthy controls than schizophrenic patients for male subjects while the difference is minimal in female subjects. These findings are well aligned with the established sex difference in schizophrenia.

Cannabidiol attenuates behavioral changes in a rodent model of schizophrenia through 5-HT1A, but not CB1 and CB2 receptors

Preclinical and clinical data indicate that cannabidiol (CBD), a non-psychotomimetic compound from the Cannabis sativa plant, can induce antipsychotic-like effects. In an animal model of schizophrenia based on the antagonism of NMDA receptors, the behavioral and molecular changes induced by repeated treatment with the NMDA receptor antagonist MK-801 were prevented when CBD was co-administered with MK-801. It is unknown, however, if CBD would reverse these changes once they have been established. Thus, in the present study we used male C57BL/6J mice, 6 weeks old, to evaluate whether daily CBD injection for seven days, starting after the end of the repeated treatment with MK-801 for 14 days, would reverse MK-801-induced deficits in the social interaction (SI) and novel object recognition (NOR) tests, which have been used to investigate the negative and cognitive symptoms of schizophrenia, respectively. We also assessed whether CBD effects would be blocked by pretreatment with AM251, a CB1 receptor antagonist, AM630, a CB2 receptor antagonist, or WAY100635, a 5-HT1A receptor antagonist. CBD and the second-generation antipsychotic clozapine, used as a positive control, attenuated the impairments in the SI and NOR tests induced by repeated administered MK-801. CBD effects were blocked by WAY100635, but not by AM251 or AM630. These data suggest that CBD induces antipsychotic-like effects by activating 5-HT1A receptors and indicate that this compound could be an interesting alternative for the treatment of negative and cognitive symptoms of schizophrenia.

Gender differences of neurocognitive functioning in patients with first-episode schizophrenia in China

AIMS

To investigate the gender differences in neurocognitive functioning in patients with first-episode schizophrenia (FES) in China.

METHODS

A total of 449 Chinese patients with FES (210 males, 239 females) were included in this study. Participants' psychopathology was assessed by the Positive and Negative Syndrome Scale (PANSS). Neurocognitive functioning was assessed by 10 neuropsychological tests from a battery. Neurocognitive test scores were converted to scale scores and t-scores using normative data from Chinese populations.

RESULTS

Males were younger and less likely to be married, had an earlier age of illness onset and a longer duration of untreated psychosis (DUP), and scored higher on the PANSS negative, general and total scales than females. After controlling for potential confounders, females performed better than males in the verbal learning and memory domain (p=0.016). While most neurocognitive domains were correlated with PANSS negative scores for male patients with FES, for female patients with FES, negative associations were found between scores on the PANSS general subscales and neurocognitive domains. We also performed a case-control comparison with a group of patients with clinically stable schizophrenia (CSS) (n=60) who were matched by age, sex and education years with patients with FES (n=58). After controlling for potential confounders, no significant differences were found between patients with FES and patients with CSS in all neurocognitive domains. Female patients still performed better in the verbal learning and memory domain (t=2.14, p=0.034). No interaction effects of gender and disease were found.

CONCLUSIONS

Gender was an independent influence factor for the verbal learning and memory domain. Both female patients with first-episode schizophrenia and female patients with clinically stable schizophrenia performed better than male patients.

Cognitive impairment and its improvement after six months in adolescents with schizophrenia

Studies evaluating the cognitive impairment in schizophrenic adolescents reported a variable course following antipsychotic treatment, with improvement being associated to patients' demographic or clinical characteristics.

Objectives

To examine the cognitive impairments of a Mexican sample of adolescents with schizophrenia using the MATRICS Consensus Cognitive Battery (MCCB) before and after six months of antipsychotic treatment and to determine which demographic or clinical characteristics could be associated to cognitive improvement.

Methods

A sample of 87 Mexican patients was evaluated with the MCCB. Domain scores for three age groups (12-13, 14-15 and 16-17 y.o.) were obtained at baseline, and after 3 and 6 months of treatment. The groups were compared for demographic and clinical variables (sex, school attendance, years of education, being on their first psychotic episode, duration of illness and mean dose of antipsychotic), and a logistic regression analysis was performed to determine which variables predicted larger improvement.

Results

The baseline performance showed scores below the standardized mean, with improvement in all domains except for social cognition; female adolescents showed a larger improvement in attention/vigilance and visual learning domains.

Conclusions

We observed cognitive impairments on schizophrenic adolescents, which improved after six months of treatment in almost all domains.

The effects of antipsychotics on the density of cannabinoid receptors in selected brain regions of male and female adolescent juvenile rats

Antipsychotic drugs have been increasingly prescribed to children and adolescents for treating various mental disorders, such as childhood-onset schizophrenia. The abnormality of endocannabinoid system is involved in the pathophysiology of these disorders in juveniles. This study investigated the effect of antipsychotics on the cannabinoid (CB) receptors in the brain of both male and female juvenile rats. The postnatal rats (PD23±1) were administered aripiprazole (1 mg/kg), olanzapine (1 mg/kg), risperidone (0.3 mg/kg) or vehicle (control) for 3 weeks. Quantitative autoradiography was used to investigate the binding densities of [³H]CP-55940 (an agonist for CB1R and CB2R) and [³H]SR141716A (a selective CB1R antagonist) in the rat brains. Risperidone significantly upregulated the [³H]CP55940 and [³H]SR141716A bindings in the prefrontal cortex (PFC), nucleus accumbens core (NAcC), nucleus accumbens shell (NAcS), cingulate cortex (Cg), and the caudate putamen (CPu) in male rats. Moreover, aripiprazole significantly elevated the [³H]SR141716A binding in the Cg and NAcS of female rats. Furthermore, there is an overall higher [³H]SR141716A binding level in the brain of female rats than male rats. Therefore, treatment with aripiprazole, olanzapine and risperidone could induce differential and gender specific effects on the binding density of cannabinoid receptors in the selected brain regions of childhood/adolescent rats.

Influence of Venus and Mars in the cognitive sky of schizophrenia. Results from the first-step national FACE-SZ cohort

OBJECTIVES

Sex differences can yield important clues regarding illness pathophysiology and its treatment. Schizophrenia (SZ) has a lower incidence rate, and a better prognosis, in women versus men. The present study investigated the cognitive profiles of both sexes in a large multi-centre sample of community-dwelling SZ patients.

METHOD

544 community-dwelling stable SZ subjects (141 women and 403 men; mean age 34.5±12.1 and 31.6±8.7years, respectively) were tested with a comprehensive battery of neuropsychological tests.

RESULTS

Although community-dwelling SZ men had more risk factors for impaired cognition (including first-generation antipsychotics administration and comorbid addictive disorders), women had lower scores on a wide range of cognitive functions, including current and premorbid intellectual functioning, working memory, semantic memory, non-verbal abstract thinking and aspects of visual exploration. However, women scored higher in tests of processing speed and verbal learning, as well as having a lower verbal learning bias. No sex difference were evident for visuospatial learning abilities, cued verbal recall, sustained attention and tests of executive functions, including cognitive flexibility, verbal abstract thinking, verbal fluency and planning abilities.

CONCLUSION

Sex differences are evident in the cognitive profiles of SZ patients. The impact on daily functioning and prognosis, as well as longitudinal trajectory, should be further investigated in the FACE-SZ follow-up study. Sex differences in cognition have implications for precision-medicine determined therapeutic strategies.

LIMITS

Given the restricted age range of the sample, future research will have to determine cognitive profiles across gender in late onset SZ.

Gender differences measured by the MATRICS consensus cognitive battery in chronic schizophrenia patients

Using Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), previous study showed significant gender differences for cognitive deficits in immediate and delayed memory in schizophrenia patients. However, RBANS does not include reasoning and problem solving, and social cognition. These cognitive functions can significantly affect the outcomes and daily life in patients. This study examined the gender differences of cognition using the measurement and treatment research to improve cognition in schizophrenia (MATRICS) consensus cognitive battery (MCCB), especially focusing on reasoning and problem solving, and social cognition in schizophrenia patients. The results showed that healthy controls exemplified better cognition than patients in both genders in all examined MCCB scores. Male healthy controls had better reasoning and problem solving and working memory than females, but these gender differences were not presented in schizophrenia patients. Also, male schizophrenia patients showed worse cognition than females on social cognition, processing speed, verbal learning and visual learning. Our results support that male schizophrenia patients had more cognitive impairment than females on reasoning and problem solving, social cognition, processing speed, working memory, verbal learning and visual learning.

Sex and diagnosis specific associations between DNA methylation of the oxytocin receptor gene with emotion processing and temporal-limbic and prefrontal brain volumes in psychotic disorders

BACKGROUND

The oxytocin (OT) system, including receptor epigenetic mechanisms, has been shown to influence emotion processing, especially in females. Whether OT receptor (OXTR) epigenetic alterations occur across psychotic disorders in relation to illness-related disturbances in social cognition and brain anatomy is unknown.

METHODS

Participants with affective and nonaffective psychotic disorders (92 women, 75 men) and healthy controls (38 women, 37 men) from the Chicago site of the BSNIP study completed the Penn Emotion Recognition Test (ER-40), a facial emotion recognition task. We measured cytosine methylation at site -934 upstream of the OXTR start codon in DNA from whole blood, and for the first time their relationship with plasma OT levels assessed by enzyme-immunoassay. Volumes of brain regions supporting social cognition were measured from MRI scans using FreeSurfer.

RESULTS

Patients with prototypic schizophrenia features showed higher levels of DNA methylation than those with prototypic bipolar features. Methylation was higher in women than men, and was associated with poorer emotion recognition only in female patients and controls. Greater methylation was associated with smaller volumes in temporal-limbic and prefrontal regions associated previously with social cognition, but only in healthy women and females with schizophrenia.

CONCLUSION

DNA methylation of the OXTR site -934 was higher in schizophrenia spectrum than bipolar patients. Among patients, it was linked to behavioral deficits in social cognition and neuroanatomic structures known to support emotion processing only in schizophrenia spectrum individuals.

Gender differences in cognitive deficits in schizophrenia with and without diabetes

This study investigated gender differences in cognition in schizophrenia with and without diabetes. Cognition was assessed in 263 individuals with schizophrenia with age range (40-68): 67 males and 34 females with schizophrenia with diabetes; and 125 males and 37 females with schizophrenia without diabetes according to the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Fasting glucose, hemoglobin A1c (HbA1c) and lipid levels were measured. Results showed that male individuals performed worse on most cognitive tasks, especially attention, in schizophrenia with than without diabetes. This result was not observed in female individuals. Also, individuals of both genders showed higher fasting glucose and HbA1c in schizophrenia with than without diabetes. In schizophrenia with diabetes, males had significantly worse cognition than females in all cognitive domains. Higher HbA1c, lower high-density lipoprotein, and an earlier age of onset of schizophrenia were found in males compared with female individuals. HbA1c was negatively associated with attention and the RBANS total score for males but not for females. In schizophrenia without diabetes, males showed worse performance in immediate and delayed memory than females. This study support cognition was worse for males with schizophrenia irrespective of whether they have diabetes. However, diabetes exemplified the gender differences, especially in attention.

Effects of sex, menstrual cycle phase, and endogenous hormones on cognition in schizophrenia

BACKGROUND

In women with schizophrenia, cognition has been shown to be enhanced following administration of hormone therapy or oxytocin. We examined how natural hormonal changes across the menstrual cycle influence cognition in women with schizophrenia. We hypothesized that female patients would perform worse on "female-dominant" tasks (verbal memory/fluency) and better on "male-dominant" tasks (visuospatial) during the early follicular phase (low estradiol and progesterone) compared to midluteal phase (high estradiol and progesterone) in relation to estradiol but not progesterone.

METHODS

Fifty-four women (23 with schizophrenia) completed cognitive assessments and provided blood for sex steroid assays and oxytocin at early follicular (days 2-4) and midluteal (days 20-22) phases. Men were included to verify the expected pattern of sex differences on cognitive tests.

RESULTS

Expected sex differences were observed on "female-dominant" and "male-dominant" tasks (p<0.001), but the magnitude of those differences did not differ between patients and controls (p=0.44). Cognitive performance did not change across the menstrual cycle on "female-dominant" or "male-dominant" tasks in either group. Estradiol and progesterone levels were unrelated to cognitive performance. Oxytocin levels did not change across the menstrual cycle but were positively related to performance on "female-dominant" tasks in female patients only (p<0.05).

CONCLUSIONS

Sex differences in cognitive function are preserved in schizophrenia. Oxytocin levels do not change across the cycle, but relate to enhanced performance on female dominant tests in women. Physiological levels of oxytocin may thus have a more powerful benefit in some cognitive domains than estrogens in schizophrenia.

The association between cognitive deficits and depressive symptoms in at-risk mental state: a comparison with first-episode psychosis

Cognitive deficits and a high prevalence of depressive symptoms have been reported in at-risk mental state (ARMS) for psychosis, but the relationships between these variables remain unclear. The Brief Assessment of Cognition in Schizophrenia (BACS) was administered to 50 individuals with ARMS, 50 with first-episode psychosis (FEP), and 30 healthy controls (HC). Clinical symptoms were assessed by the Positive and Negative Syndrome Scale (PANSS) and the Beck Depression Inventory-2nd edition (BDI-II). Composite z-scores in BACS were compared between the three groups. Pearson correlations between composite z-scores on the BACS and indices of clinical symptoms were compared in the ARMS and FEP groups. The mean composite z-scores on the BACS for the ARMS (-2.82) and FEP (-2.85) groups were significantly lower than the HC group (P<0.001); no differences between the ARMS and FEP groups emerged (P=0.995). Cognitive deficits and depressive symptoms were significantly correlated in the ARMS group (PANSS depression: r=-0.36, P=0.010; BDI-II: r=-0.34, P=0.02), while the correlation between cognitive deficits and negative symptoms was significant in the FEP group (r=-0.46, P=0.001) and approached significance in the ARMS group (r=-0.25, P=0.08). The correlation between cognitive deficits and depressive symptoms significantly differed between the ARMS and FEP groups (PANSS depression: Z=2.50, P=0.012; BDI-II: Z=1.96, P=0.0499). Thus, a relationship between cognitive deficits and depression appears to be specific to ARMS compared to FEP.

Gender difference in association of cognition with BDNF in chronic schizophrenia

While numerous studies have reported that brain-derived neurotrophic factor (BDNF) may be involved in the pathophysiology of schizophrenia, very few studies have explored its association with cognitive impairment or gender differences in schizophrenia which we explored. We compared gender differences in 248 chronic schizophrenic patients (male/female=185/63) to 188 healthy controls (male/female=98/90) on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and serum BDNF. Schizophrenic symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). Our results showed that schizophrenic patients performed worse than normals on most of the cognitive tasks, and male patients had significantly lower immediate memory and delayed memory scores than female patients. BDNF levels were significantly lower in patients than controls, and male patients had significantly lower BDNF levels than female patients. For the patients, BDNF was positively associated with immediate memory and the RBANS total score. Furthermore, these associations were only observed in female not male patients. Among healthy controls, no gender difference was observed in cognitive domains and BDNF levels, or in the association between BDNF and cognition. Our results suggest gender differences in cognitive impairments, BDNF levels and their association in chronic patients with schizophrenia. However, the findings should be regarded as preliminary due to the cross-sectional design and our chronic patients, which need replication in a first-episode and drug naïve patients using a longitudinal study.

No sex differences in neuropsychological performance in first episode psychosis patients

OBJECTIVE

The purpose of this study was to verify whether male patients with psychosis have greater neurocognitive impairment than female patients at illness onset.

METHOD

Participants with a first episode of psychosis (74 women/86 men) and healthy controls (62 women/97 men) were assessed with an extensive neuropsychological test battery.

RESULTS

Women in the clinical group were older at illness onset and had achieved higher formal education than men. This trend was the same for the control group. The patient group presented with lower premorbid IQ compared to healthy controls, and performed below for most neuropsychological tests. Women scored higher than men on a test of verbal memory, whereas men scored higher than women on a test of reaction time, visual memory, and a planning task. There were no group-by-sex interactions for any of the neuropsychological tests.

CONCLUSION

The present study shows that at the onset of psychosis there are no differences between males and females in neuropsychological performance. The differential pattern of cognitive performance observed is similar to that in healthy males and females. Furthermore, females with a late onset of psychosis may represent a subgroup with specific visuospatial and problem solving impairments.

Gender differences in neuropsychological performance across psychotic disorders--a multi-centre population based case-control study

BACKGROUND

Patients with schizophrenia and other psychoses exhibit a wide range of neuropsychological deficits. An unresolved question concerns whether there are gender differences in cognitive performance.

METHODS

Data were derived from a multi-centre population based case-control study of patients with first-episode psychosis. A neuropsychological test battery was administered to patients with a diagnosis of schizophrenia or schizoaffective disorder (N=70, 36% females), bipolar/mania (N=34, 60% females), depressive psychosis (N=36, 58% females) and healthy controls (N=148, 55% females). Generalized and specific cognitive deficits were compared.

RESULTS

There was strong evidence for disorder-specific gender differences in neuropsychological performance. Males and females with schizophrenia showed similar pervasive neuropsychological impairments. In psychotic depressive disorder females performed worse than males across neuropsychological measures. Differences in neuropsychological performance between males and females with bipolar/manic disorder were restricted to language functions. Symptom severity did not contribute to the observed gender differences.

CONCLUSIONS

Early in the course of psychotic illness, gender related factors appear to moderate the severity of cognitive deficits in depressive psychosis and bipolar/mania patients.

Gender differences in cognitive function of patients with chronic schizophrenia

Schizophrenic patients have cognitive impairments, but gender differences in these cognitive deficits have had limited study. This study assessed cognitive functioning in 471 subjects including 122 male and 78 female schizophrenic patients and 141 male and 130 female healthy controls. We found that immediate memory, language, delayed memory and total RBANS scores were significantly decreased in schizophrenia compared with healthy controls for both genders. Male patients had significant lower immediate memory, delayed memory and total RBANS scores than female patients, and healthy controls showed a similar gender difference. The RBANS showed modest correlations with PANSS scores, duration of illness and antipsychotic dose (chlorpromazine equivalents). Almost all RBANS scores in the schizophrenics and healthy controls showed significant positive correlations with education. Thus, patients of both sexes with schizophrenia experienced more deteriorated performance than healthy controls on cognitive domains of immediate memory, language and delayed memory. Furthermore, male schizophrenic patients had more serious cognitive deficits than female patients in immediate and delayed memory, but not in language, visuospatial and attention indices.

Sex differences in human lymphoblastoid cells sensitivities to antipsychotic drugs

Adverse drug reactions (ADRs) are a major concern in pharmacotherapy and are more common among women. Immortalized human lymphoblastoid cell lines (LCLs) are emerging as a novel tool for studying interindividual variability in drug response, including ADRs. In the present study, we compared sensitivities of LCLs from unrelated healthy male and female donors to growth inhibition by a panel of common drugs. We observed large interindividual drug sensitivity variations with similar mean sensitivities recorded for LCLs from male and female donors for most tested drugs. A notable exception was observed for the typical antipsychotic haloperidol and the atypical antipsychotic risperidone, which exhibited, on average, more robust in vitro growth inhibition in male as compared with female LCLs. An opposite finding was observed for the antidepressant paroxetine, which was more potent for inhibiting the growth of female as compared with male LCLs. These observations are discussed in the context of the higher incidence of dystonia reported for male schizophrenia patients treated with haloperidol and the higher efficacy of paroxetine in female major depression patients.

Schizophrenia is associated with dysregulation of a Cdk5 activator that regulates synaptic protein expression and cognition

Cyclin-dependent kinase 5 is activated by small subunits, of which p35 is the most abundant. The functions of cyclin-dependent kinase 5 signalling in cognition and cognitive disorders remains unclear. Here, we show that in schizophrenia, a disorder associated with impaired cognition, p35 expression is reduced in relevant brain regions. Additionally, the expression of septin 7 and OPA1, proteins downstream of truncated p35, is decreased in schizophrenia. Mimicking a reduction of p35 in heterozygous knockout mice is associated with cognitive endophenotypes. Furthermore, a reduction of p35 in mice results in protein changes similar to schizophrenia post-mortem brain. Hence, heterozygous p35 knockout mice model both cognitive endophenotypes and molecular changes reminiscent of schizophrenia. These changes correlate with reduced acetylation of the histone deacetylase 1 target site H3K18 in mice. This site has previously been shown to be affected by truncated p35. By restoring H3K18 acetylation with the clinically used specific histone deacetylase 1 inhibitor MS-275 both cognitive and molecular endophenotypes of schizophrenia can be rescued in p35 heterozygous knockout mice. In summary, we suggest that reduced p35 expression in schizophrenia has an impact on synaptic protein expression and cognition and that these deficits can be rescued, at least in part, by the inhibition of histone deacetylase 1.

A closer look at siblings of patients with schizophrenia: the association of depression history and sex with cognitive phenotypes

BACKGROUND

Siblings of patients with schizophrenia show impaired cognition and an increased prevalence of depression history. Although sex has been shown to moderate cognition in patients, this effect has not been examined in siblings. Here we elucidate how a history of depression and sex influences cognition in siblings unaffected by schizophrenia.

METHODS

Unaffected siblings of patients with schizophrenia and unrelated healthy controls were evaluated neuropsychologically and completed structured clinical interviews. Participants with a depression history or no psychiatric history were selected for the sample. Cognitive performance of siblings (n=366) and controls (n=680) was first examined. Second, cognition of participants with a depression history and those without a psychiatric history was compared while additionally investigating the role of schizophrenia risk and sex.

RESULTS

Relative to controls, siblings, with and without a psychiatric history, demonstrated significant (p<.05) cognitive deficits. Depression history impaired cognition in siblings, but not in controls; whereas sex affected cognition in both siblings and controls. In siblings alone, sex significantly interacted with depression history to influence cognition. This interaction revealed that in male--but not female--siblings a history of depression was associated with greater cognitive impairments.

CONCLUSION

A history of depression impairs cognition in siblings, but not in controls. Moreover, depression history interacts with sex and demonstrates that only cognition in male siblings is significantly and additionally compromised by a history of depression. This interaction may be an important consideration for future phenotype and genetic association studies.

Cognitive differences between men and women: a comparison of patients with schizophrenia and healthy volunteers

Gender modulates cognition such that women display advantages in certain domains while men excel in others tasks. Similar patterns have been seen in patients with schizophrenia. We derived six cognitive factor domain scores from a cognitive battery and examined gender-based cognitive differences in patients with schizophrenia and controls. There were strikingly different effects of gender in patients as compared to controls. The large sample size and broad range of tests in our study add important findings to the neuropsychological literature of schizophrenia, which serve to reinforce some aspects of past research on gender differences in cognition, while questioning others.

A female advantage in basic face recognition is absent in schizophrenia

Healthy females outperform males on face recognition tasks. Relative to healthy individuals, schizophrenia patients are impaired at face perception. Yet, it is unclear whether the female advantage found in healthy controls is preserved in females with schizophrenia. In the present study, we compared male and female patients and healthy controls on two basic face perception tasks - detection and identity discrimination. In the detection task, subjects located an upright or inverted line-drawn face (or tree) embedded within a larger line-drawing. In the identity discrimination task, subjects determined which of two side-by-side face images matched an earlier presented face image. Healthy females were significantly more accurate than healthy males on face detection, but not on identity discrimination. However, female patients were not more accurate than male patients on either task. On both upright face detection and face identity discrimination, healthy controls significantly outperformed patients. Patients' performance on face detection was closely associated with tree detection and IQ scores, as well as level of psychosis. This pattern of results suggests that a female advantage in basic face perception is no longer available in schizophrenia, and that this absence may be related to a generalized deficit factor which acts to level performance across sexes, and putative changes in sex-related neurobiological differences associated with schizophrenia.

A comparison of neuropsychological dysfunction in first-episode psychosis patients with unipolar depression, bipolar disorder, and schizophrenia

The severity and profile of cognitive dysfunction in first episode schizophrenia and psychotic affective disorders were compared before and after antipsychotic treatment. Parallel recruitment of consecutively admitted study-eligible first-episode psychotic patients (30 schizophrenia, 22 bipolar with psychosis, and 21 psychotic depression) reduced confounds of acute and chronic disease/medication effects as well as differential treatment and course. Patient groups completed a neuropsychological battery and were demographically similar to healthy controls (n=41) studied in parallel. Prior to treatment, schizophrenia patients displayed significant deficits in all cognitive domains. The two psychotic affective groups were also impaired overall, generally performing intermediate between the schizophrenia and healthy comparison groups. No profile differences in neuropsychological deficits were observed across patient groups. Following 6 weeks of treatment, no patient group improved more than practice effects seen in healthy individuals, and level of performance improvement was similar for affective psychosis and schizophrenia groups. Although less severe in psychotic affective disorders, similar profiles of generalized neuropsychological deficits were observed across patient groups. Recovery of cognitive function after clinical stabilization was similar in mood disorders and schizophrenia. To the extent that these findings are generalizable, neuropsychological deficits in psychotic affective disorders, like schizophrenia, may be trait-like deficits with persistent functional implications.

Enhanced latent inhibition in dopamine receptor-deficient mice is sex-specific for the D1 but not D2 receptor subtype: implications for antipsychotic drug action

Latent inhibition (LI) is reduced learning to a stimulus that has previously been experienced without consequence. It is an important model of abnormal allocation of salience to irrelevant information in patients with schizophrenia. In rodents LI is abolished by psychotomimetic drugs and in experimental conditions where LI is low in controls, its expression is enhanced by antipsychotic drugs with activity at dopamine (DA) receptors. It is however unclear what the independent contributions of DA receptor subtypes are to these effects. This study therefore examined LI in congenic DA D1 and D2 receptor knockout (D1 KO and D2 KO) mice. Conditioned suppression of drinking was used as the measure of learning in the LI procedure. Both male and female DA D2 KO mice showed clear enhancement of LI reproducing antipsychotic drug effects in the model. Unexpectedly, enhancement was also seen in D1 KO female mice but not in D1 KO male mice. This sex-specific pattern was not replicated in locomotor or motor coordination tasks nor in the effect of DA KOs on baseline learning in control groups indicating some specificity of the effect to LI. These data suggest that the dopaminergic mechanism underlying LI potentiation and possibly antipsychotic action may differ between the sexes, being mediated by D2 receptors in males but by both D1 and D2 receptors in females. These data suggest that the DA D1 receptor may prove an important target for understanding sex differences in the mechanisms of action of antipsychotic drugs and in the aetiology of aberrant salience allocation in schizophrenia.