COVID-19-related intrusive thoughts and associated ritualistic behaviors.

This study evaluated COVID-19-related intrusive thoughts and associated ritualistic behaviors (CITRB). From March to May 2020, 1,118 Chinese high school students, college students, psychiatric outpatients, and community members completed a survey assessing CITRB, generalized anxiety, depression, somatization, obsessive-compulsive symptoms, and pandemic-related disruptions. Overall, participants reported mild to moderate CITRB, although certain thoughts/behaviors were more frequently endorsed, such as repeatedly telling others to take precautions against COVID-19 and checking COVID-19-related news. Being male, younger, a health-care worker, or in isolation/quarantine was associated with CITRB severity in community members. Obsessive-compulsive symptom severity, depression, somatic symptoms, and anxiety were associated with CITRB severity, although only obsessive-compulsive symptoms were uniquely associated with CITRB. This study provided evidence for the construct of CITRB, which may help mental health providers identify the nature and sources of COVID-19-related distress for some individuals as well as serve as a framework for evaluating obsessive-compulsive symptoms specific to large-scale crises.

Optic nerve sheath diameter and spaceflight: defining shortcomings and future directions.

Neuro-ocular changes during long-duration space flight are known as spaceflight-associated neuro-ocular syndrome (SANS). The ability to detect, monitor, and prevent SANS is a priority of current space medicine research efforts. Optic nerve sheath diameter (ONSD) measurement has been used both terrestrially and in microgravity as a proxy for measurements of elevated intracranial pressure. ONSD shows promise as a potential method of identifying and quantitating neuro-ocular changes during space flight. This review examines 13 studies measuring ONSD and its relationship to microgravity exposure or ground-based analogs, including head-down tilt, dry immersion, or animal models. The goal of this correspondence is to describe heterogeneity in the use of ONSD in the current SANS literature and make recommendations to reduce heterogeneity in future studies through standardization of imaging modalities, measurement techniques, and other aspects of study design.

Identification of an optimal dose of intravenous ketamine for late-life treatment-resistant depression: a Bayesian adaptive randomization trial.

Evidence supporting specific therapies for late-life treatment-resistant depression (LL-TRD) is necessary. This study used Bayesian adaptive randomization to determine the optimal dose for the probability of treatment response (≥50% improvement from baseline on the Montgomery-Åsberg Depression Rating Scale) 7 days after a 40 min intravenous (IV) infusion of ketamine 0.1 mg/kg (KET 0.1), 0.25 mg/kg (KET 0.25), or 0.5 mg/kg (KET 0.5), compared to midazolam 0.03 mg/kg (MID) as an active placebo. The goal of this study was to identify the best dose to carry forward into a larger clinical trial. Response durability at day 28, safety and tolerability, and effects on cortical excitation/inhibition (E/I) ratio using resting electroencephalography gamma and alpha power, were also determined. Thirty-three medication-free US military veterans (mean age 62; range: 55-72; 10 female) with LL-TRD were randomized double-blind. The trial was terminated when dose superiority was established. All interventions were safe and well-tolerated. Pre-specified decision rules terminated KET 0.1 (N = 4) and KET 0.25 (N = 5) for inferiority. Posterior probability was 0.89 that day-seven treatment response was superior for KET 0.5 (N = 11; response rate = 70%) compared to MID (N = 13; response rate = 46%). Persistent treatment response at day 28 was superior for KET 0.5 (response rate = 82%) compared to MID (response rate = 37%). KET 0.5 had high posterior probability of increased frontal gamma power (posterior probability = 0.99) and decreased posterior alpha power (0.89) during infusion, suggesting an acute increase in E/I ratio. These results suggest that 0.5 mg/kg is an effective initial IV ketamine dose in LL-TRD, although further studies in individuals older than 75 are required.