[¹¹C]K-2, a radiotracer exhibiting high affinity and selectivity for α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs), is suitable for the quantification of AMPARs in living human brains and potentially useful in the identification of epileptogenic foci in patients. This study aimed to estimate the radiation doses of [¹¹C]K-2 in various organs and calculate the effective dose after injection of [¹¹C]K-2 in healthy human subjects. Twelve healthy male subjects were registered and divided into two groups (370 or 555 MBq of [¹¹C]K-2), followed by 2 h whole-body scans. We estimated the radiation dose of each organ and then calculated the effective dose for each subject. The highest uptake of [¹¹C]K-2 was observed in the liver, while the brain also showed relatively high uptake. The urinary bladder exhibited the highest radiation dose. The kidneys and liver also showed high radiation doses after [¹¹C]K-2 injections. The effective dose of [¹¹C]K-2 ranged from 5.0 to 5.2 μSv/MBq. Our findings suggest that [¹¹C]K-2 is safe in terms of the radiation dose and adverse effects. The injection of 370–555 MBq (10 to 15 mCi) for PET studies using this radiotracer is applicable in healthy human subjects and enables serial PET scans in a single subject.

Objective: Mental health issues among employees cause significant productivity losses through presenteeism and absenteeism. This study aimed to quantify productivity losses caused by employees with mental health issues in Japan. Methods: Participants were recruited to match the Japanese population distribution by gender, age, and region. Mental health status and productivity loss were assessed using self-administered questionnaires. The results were extrapolated to estimate nationwide impact calculated using probabilistic sensitivity analysis. Results: We analyzed 27,507 individuals. Productivity loss due to mental health–related presenteeism was estimated at $46.73 billion, and absenteeism at $1.85 billion, equivalent to 1.1% of Japan’s GDP and over seven times the medical costs for mental disorders. Women in their 20s reported more mental health issues than men. Conclusions: These results highlight the urgent need for businesses and governments to enhance workplace mental health measures.

Journal of Medical Internet Research - International Scientific Journal for Medical Research, Information and Communication on the Internet #Preprint #PeerReviewMe: Warning: This is a unreviewed preprint. Readers are warned that the document has not been peer-reviewed by expert/patient reviewers or an academic editor, may contain misleading claims, and is likely to undergo changes before final publication, if accepted, or may have been rejected/withdrawn. Readers with interest and expertise are encouraged to sign up as peer-reviewer, if the paper is within an open peer-review period. Please cite this preprint only for review purposes or for grant applications and CVs (if you are the author). Background: The mental health of children and adolescents is a growing public health concern, with increasing rates of depression and anxiety impacting their emotional, social, and academic well-being. In Japan, access to timely psychiatric care is limited, leading to extended waiting periods that can range from three months to a year. AI-driven chatbots, such as emol, which integrate Acceptance and Commitment Therapy (ACT), show potential as digital solutions to support young patients during these waiting times. The AI chatbot emol was selected based on a comprehensive review of Japanese mental health technology applications, including in-person evaluations with company representatives. Objective: This exploratory, parallel-group randomized controlled trial examined the feasibility of using AI chatbot emol with pediatric and adolescent individuals on psychiatric waiting lists. Methods: Participants aged 12-18 years were recruited from four hospitals in Kanagawa Prefecture and randomly assigned to either an intervention group, receiving eight weekly chatbot sessions, or a control group, receiving standard mental health information. The primary outcome was change in Patient Health Questionnaire-9 (PHQ-9) scores from pre- to post-intervention. Secondary assessments, such as voice and writing pressure analysis, provided additional engagement metrics, with data collected at baseline, during the intervention, and at week 9. Results: Of the 96 eligible individuals on psychiatric waiting lists, eight expressed interest, and three provided initial consent. However, all participants subsequently withdrew or were excluded, resulting in no evaluable data for analysis. Low engagement may have been influenced by the perceived irrelevance of digital tools, complex protocols, and privacy concerns． Conclusions: Significant barriers to engagement suggest that digital interventions may need simpler protocols and trusted environments to improve feasibility. Future studies could test these interventions in supportive settings, like schools or community centers, to enhance accessibility and participation among youth. Clinical Trial: Trial Registration: Japan Registry of Clinical Trials (jRCT) jRCT1032230427; https://jrct.niph.go.jp