This chapter examines how the integration of demography and population intelligence within multimodal artificial intelligence (AI) is reshaping modern healthcare. It argues that demographic knowledge plays a vital role in ensuring that AI systems are equitable, context-aware, and socially grounded. By combining clinical, genomic, behavioral, and environmental data with demographic insights, multimodal AI can better reflect the diversity of real-world populations and make more accurate, inclusive predictions. The health surveillance, chronic disease prediction, and epidemiological forecasting—fields where social and biological diversity deeply influence outcomes. It also highlights the ethical and policy challenges that arise when demographic data are used in algorithmic decision-making, calling for transparency, fairness, and privacy. Through the lenses of systems thinking and data ecology, the discussion emphasizes that AI should not only optimize performance but also strengthen trust, accountability, and community participation in digital health systems. Ultimately, the chapter envisions multimodal AI as a bridge between human insight and computational intelligence—capable of transforming data into compassionate, population-conscious healthcare for an increasingly diverse and interconnected world.