Language about the future on social media as a novel marker of anxiety and depression: A big-data and experimental analysis

Anxiety and depression are mood disorders which negatively impact many people. Psychology studies suggest depression is associated with future time horizons, or how "far" into the future people tend to think, and anxiety is associated with temporal discounting, or how much people devalue delayed future rewards. Separate studies from linguistics and economics have shown that individual differences in how people refer to future time predict temporal discounting. Yet no one—that we know of—has investigated whether future time reference habits are a marker of anxiety and/or depression. In Study 1, we analysed data from the social media website Reddit to test for relationships between these variables. Users who had previously posted popular contributions to forums dedicated to anxiety and depression referenced the future and the past more often than controls, had more proximal future and past time horizons, and significantly differed in their linguistic future time reference patterns. They used fewer future tense constructions (e.g. will), fewer high-certainty constructions (e.g. certainly), more low-certainty constructions (e.g. could), more bouletic modal constructions (e.g. hope), and more deontic modal constructions (e.g. must). This motivated Study 2, a survey-based mediation analysis. Self-reported anxious participants represented future events as more temporally distal and therefore temporally discounted to a greater degree. The same was not true of depression. We contextualise the results using two theoretical frameworks: construal level theory and functionalist approaches to clinical psychology. We conclude that methods which combine big-data with experimental paradigms can help identify novel markers of mental illness, which can aid in the development of new therapies and diagnostic criteria.