Mental health in digital microsystems across three Asian Reddit communities

Mental health is increasingly discussed in online forums, especially in countries where access to formal services remains limited or stigmatized. This study explores how mental health discourse unfolds across Reddit communities in India, the Philippines, and Singapore-three culturally distinct nations with rising digital engagement. Drawing on 13,888 posts and 218,570 comments collected from r/india, r/philippines, and r/singapore, we apply machine learning based BERTopic modeling and zero-shot classification to examine temporal trends, posting intent, and community response styles across ten identified mental health topics. Mental health discussions were found to intensify in response to both global and country-specific events, with notable spikes corresponding to periods of collective stress or sociopolitical change. "Seeking Support" was the most common posting intent overall (41.5%), dominating in career and therapy discussions (up to 60%) but dropping significantly in suicide-related posts (17.1%), where "Venting" peaked at 45.4%. Posts concerning major societal events received substantially higher comment volumes, whereas discussions focused on internalized distress, such as depression, tended to generate fewer responses. The tone and style of replies reflected topic sensitivity-moral framing was more frequent in crisis-related threads, and interpersonal conflict was more common in discussions involving family dynamics. Cultural distinctions were evident in how users engaged with content: some communities showed a greater tendency toward sharing personal experiences, while others emphasized emotional restraint, prosocial support, or practical advice. These variations highlight how cultural norms, social expectations, and the topic contexts shape mental health discourse and peer-to-peer interaction in online environments. The work also highlights the utility of ecological systems theory in framing how users interact within digital microsystems under the influence of broader socio-cultural developments over time.