Given the prevalence of negativity and sensationalism in the news, I suspect individuals are also varyingly susceptible to (worsening) mental health issues arising from prolonged exposure. Perhaps as reports of distant events accumulate as an overall negative impression of the person's environment.
Research clearly shows that both nature and nurture play important roles in the genesis of psychopathology. (Tsuang, et al. 2004).
Have there been any studies at all investigating the significance of news as part of that environment as a cause of mental disorders?
Tsuang, M. T., Bar, J. L., Stone, W. S., & Faraone, S. V. (2004). Gene-environment interactions in mental disorders. World Psychiatry, 3(2), 73. pmcid: 1414673