Quantify the global mental health treatment gap — the proportion of people with diagnosable mental disorders who receive no treatment — estimate the macroeconomic cost of untreated mental illness, and evaluate the evidence base for scalable digital and community-based interventions as alternatives to the specialist-led model.

WHO Mental Health Atlas 2023 cross-referenced with GBD (Global Burden of Disease) 2024 mental health estimates. Lancet Commission on Global Mental Health economic modelling. Systematic review of 140 randomized controlled trials of digital mental health interventions (apps, telehealth, chatbot-assisted CBT) published 2018-2024. Delphi expert consensus on task-shifting evidence in low-resource settings.

Mental health conditions account for 1 in 5 years lived with disability globally. Depression and anxiety alone cost the global economy $1 trillion per year in lost productivity. The treatment gap is 76-85% in low-income countries — meaning fewer than 1 in 4 people with a diagnosable mental disorder receive any treatment.

There are fewer than 1 psychiatrist per 100,000 people in 60% of countries. 5 (moderate) for depression and anxiety in RCT settings, comparable to low-intensity face-to-face interventions.

Task-shifting to trained community health workers — validated in programs like Kenya's Friendship Bench and India's SMART Mental Health — can deliver evidence-based psychological first aid at $50-150 per DALY averted, making it among the most cost-effective health interventions globally.

Critically, social determinants (housing insecurity, income poverty, conflict) drive 40-60% of mental health burden — interventions that ignore upstream determinants show high relapse rates.