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

Cariprazine and Cognition in Patients with Schizophrenia and Bipolar Disorder: A Systematic Review

BACKGROUND

Cariprazine (CAR), an antipsychotic with partial agonism at the D3 receptor and higher affinity than dopamine, has shown significant procognitive effects in preclinical animal studies. This study systematically reviews CAR's effects on cognitive measures in patients with schizophrenia and bipolar disorder.

METHODS

Two independent reviewers systematically searched PubMed, Web of Science, Scopus, and the Cochrane Library up to May 2024, following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Additional studies were found by hand searching the references of included studies. Eligible studies were randomized controlled trials (RCTs) in English that assessed CAR's effects on cognition in patients with schizophrenia or bipolar disorder. Quality was assessed using the Jadad scale.

RESULTS

Out of 139 reports, 5 studies (involving 6,104 patients with schizophrenia or bipolar disorder) were included. In schizophrenia, CAR showed better cognitive outcomes (mainly indirect measures) than placebo (PBO) in both early and late stages. It also outperformed risperidone and aripiprazole in attention-related cognitive tests. In bipolar disorder, CAR improved cognition compared to PBO (also using indirect measures). Most studies found the greatest cognitive benefits with low doses of CAR (1.5-3 mg/d).

CONCLUSIONS

CAR improved cognitive measures compared to PBO and other D2 antagonists or partial agonists in RCTs, especially in patients with greater baseline impairment. Thus, CAR may be a promising option for enhancing cognition in schizophrenic and bipolar patients; though, more trials using specific cognitive assessment tools are needed.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42023485028.

Mismatch negativity in schizophrenia spectrum and bipolar disorders: Group and sex differences and associations with symptom severity

OBJECTIVE

Research increasingly implicates glutamatergic dysfunction in the pathophysiologies of psychotic disorders. Auditory mismatch negativity (MMN) is an electroencephalography (EEG) waveform linked to glutamatergic neurotransmission and is consistently attenuated in schizophrenia (SCZ). MMN consists of two subcomponents, the repetition positivity (RP) and deviant negativity (DN) possibly reflecting different neural mechanisms. However, whether MMN reduction is present across different psychotic disorders, linked to distinct symptom clusters, or related to sex remain to be clarified.

METHODS

Four hundred participants including healthy controls (HCs; n = 296) and individuals with SCZ (n = 39), bipolar disorder (BD) BD typeI (n = 35), or BD type II (n = 30) underwent a roving MMN paradigm and clinical evaluation. MMN, RP and DN as well their memory traces were recorded at the FCZ electrode. Analyses of variance and linear regression models were used both transdiagnostically and within clinical groups.

RESULTS

MMN was reduced in SCZ compared to BD (p = 0.006, d = 0.55) and to HCs (p < 0.001, d = 0.63). There was a significant group × sex interaction (p < 0.003) and the MMN impairment was only detected in males with SCZ. MMN amplitude correlated positively with Positive and Negative Syndrome Scale total score and negatively with Global Assessment of Functioning Scale score. The deviant negativity was impaired in males with SCZ. No group differences in memory trace indices of the MMN, DN, or RP.

CONCLUSION

MMN was attenuated in SCZ and correlated with greater severity of psychotic symptoms and lower level of functioning. Our results may indicate sex-dependent differences of glutamatergic function in SCZ.

P50 sensory gating, cognitive deficits and depressive symptoms in first-episode antipsychotics-naïve schizophrenia

OBJECTIVE

Sensory gating P50 (SG-P50) may be involved in the pathophysiological mechanisms of impaired cognition in schizophrenia (SCZ). Comorbid depressive symptoms are common in SCZ patients and are also found to be associated with their cognitive impairment. However, it is unclear whether SG-P50 is abnormal in first episode antipsychotics naïve (FEAN) SCZ patients with depressive symptoms. Our aimed to investigate the relationships between SG-P50, depressive symptoms and neurocognition in FEAN-SCZ patients.

METHODS

We recruited 103 FEAN-SCZ patients (depression: n = 63; non-depression: n = 40) and 55 healthy controls. SG-P50 was measured using the standard auditory dual-click (S1&S2) paradigm. Clinical symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS) and the Hamilton Depression Rating Scale-17 (HDRS-17). Cognitive performance was evaluated using the MATRICS Consensus Cognitive Battery (MCCB).

RESULTS

Compared with non-depressive patients, depressive patients had a significantly larger S2 amplitude (p = 0.005) and a higher S2/S1 ratio at trend level (p = 0.075) after corrected. There were significant differences in the scores of CPT-IP and Mazes (NAB) between depressive and non-depressive FEAN-SCZ patients (both p values < 0.05). For all patients, the SG-P50 S2/S1 ratio was significantly correlated with HDRS-17 score (r = 0.23, p = 0.020) and MCCB-Symbol coding (r = -0.16, p = 0.043). For depressive FEAN-SCZ patients, S2 amplitude was an independent predictor of the MCCB-Mazes (NAB) (β = -0.31, t = -2.52, p = 0.015).

CONCLUSIONS

SG-P50 deficit may be an informational biomarker for depressive symptoms and neurocognitive impairments in FEAN-SCZ patients.