Accepted for/Published in: Journal of Medical Internet Research
Date Submitted: Mar 10, 2026
Date Accepted: Jul 30, 2026
Warning: This is an author submission that is not peer-reviewed or edited. Preprints - unless they show as "accepted" - should not be relied on to guide clinical practice or health-related behavior and should not be reported in news media as established information.
Naturalistic Online Language as a Marker of Depression in Midlife and Older Adults: Longitudinal Multi-Method Study
ABSTRACT
Background:
Social media use among older adults continues to grow. Many people use social media to establish meaningful social ties and discuss their mental health. Depression in midlife and older adults is a critical public health concern, yet scalable, sensitive methods for early detection remain limited. Natural language processing offers new opportunities to examine cognitive-affective processes through online language in typically understudied populations.
Objective:
This study examined whether emotional and cognitive features of naturalistic social media language are associated with depression diagnosis and symptom severity among midlife and older adults.
Methods:
We constructed cohorts of adults aged 50+ from Reddit (n = 688) and Bluesky (n = 210). Depressed and never-diagnosed control participants were recruited via a self-report survey on Prolific, which assessed depression history, age of diagnosis, current symptoms, and social media handles. Public posts were preprocessed and analyzed using a validated rule-based sentiment analysis approach to quantify emotional tone. Sentiment measures were aggregated at the user level and compared by depression status within and across platforms.
Results:
On Bluesky, depressed users exhibited significantly more negative emotional language compared to non-depressed users, as reflected by lower overall sentiment scores (ρ = -.16, P <.001). On Reddit, negative emotional language increased as depression severity increased (ρ = -.09, P= .03). These findings indicate a platform-specific relationship between depression status and expressed negative sentiment among older adults.
Conclusions:
Negative emotional tone expressed on Bluesky is associated with depression status (ever diagnosed vs. never diagnosed) among midlife and older adults, while negative emotional tone expressed on Reddit is associated with depression severity, suggesting that both overall emotional tone and longitudinal affective patterns vary by platform and clinical context. These results highlight the value of sentiment-based language markers for detecting depression-related differences in online expression within emerging social media platforms and underscore the importance of considering platform context when leveraging digital language as a marker of mental health in aging populations. Clinical Trial: n/a
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