avatar legends has confirmed that kya was taught both waterbending combat and waterbending medicine! she belonged to the first generation of young waterbenders to be taught both side by side, implying that there were many others that master katara had taught.
The disease model of depression stopped making sense to me as a psychologist when I worked with so many clients who lived in poverty, who could barely make ends meet, and who had no time for creativity or purpose. Depression is a response.