The COVID-19 pandemic has had a globally devastating psychosocial impact. A detailed understanding of the mental health implications of this worldwide crisis is critical for successful mitigation of and preparation for future pandemics. Using a large international sample, we investigated in the present study the relationship between multiple COVID-19 parameters (both disease characteristics and government responses) and the incidence of the suicide crisis syndrome (SCS), an acute negative affect state associated with near-term suicidal behavior.

Data were collected from 5528 adults across 10 different countries in an anonymous web-based survey between June 2020 and January 2021.

Individuals scoring above the SCS cut-off lived in countries with higher peak daily cases and deaths during the first wave of the pandemic. Additionally, the longer participants had been exposed to markers of pandemic severity (eg, lockdowns), the more likely they were to screen positive for the SCS. Findings reflected both country-to-country comparisons and individual variation within the pooled sample.

Both the pandemic itself and the government interventions utilized to contain the spread appear to be associated with suicide risk. Public policy should include efforts to mitigate the mental health impact of current and future global disasters.

Objectives: Bipolar disorder (BD) is a mental illness associated with higher rates of suicide. The present study aims to investigate the brain mitochondrial respiratory chain activity in an animal model of mania induced by ouabain.

Methods: Adult male Wistar rats received a single intracerebroventricular administration of ouabain (10−3 and 10−2 M) or vehicle. Locomotor activity was measured using the open field test. Mitochondrial respiratory chain activity was measured in the brain of rats 1 h and 7 days after ouabain administration.

Results: Our results showed that spontaneous locomotion was increased 1 h and 7 days after ouabain administration. Complexes I, III and IV activities were increased in the prefrontal cortex, hippocampus and striatum immediately after the administration of ouabain, at the concentration of 10−3 and 10−2 M. Moreover, complex II activity was increased only in the prefrontal cortex at the concentration of 10−2 M. On the other hand, no significant alterations were observed in complex I activity 7 days after ouabain administration. However, an increase in complexes II, III and IV activities was observed only in the prefrontal cortex at the concentration of 10−2 M.

Conclusion: Our findings suggest an increase in the activities of mitochondrial respiratory chain in this model of mania. A possible explanation is that these findings occur as a rebound effect trying to compensate for a decrease of ATP deprivation in BD. The present findings suggest that this model may present good face validity and a limitation in construct validity.

Cognitive deficits in schizophrenia play a crucial role in its clinical manifestation and seem to be related to changes in the cholinergic system, specifically the action of acetylcholinesterase (AChE). Considering this context, the aim of this study was to evaluate the chronic effects of ketamine in the activity of AChE, as well as in behavioural parameters involving learning and memory.

The ketamine was administered for 7 days. A duration of 24 h after the last injection, the animals were submitted to behavioural tests. The activity of AChE in prefrontal cortex, hippocampus and striatum was measured at different times after the last injection (1, 3, 6 and 24 h).

The results indicate that ketamine did not affect locomotor activity and stereotypical movements. However, a cognitive deficit was observed in these animals by examining their behaviour in inhibitory avoidance. In addition, an increase in AChE activity was observed in all structures analysed 1, 3 and 6 h after the last injection. Differently, serum activity of AChE was similar between groups.

Chronic administration of ketamine in an animal model of schizophrenia generates increased AChE levels in different brain tissues of rats that lead to cognitive deficits. Therefore, further studies are needed to elucidate the complex mechanisms associated with schizophrenia.