  Depression is a leading cause of disability worldwide, but is often
under-diagnosed and under-treated. One of the tenets of cognitive-behavioral
therapy (CBT) is that individuals who are depressed exhibit distorted modes of
thinking, so-called cognitive distortions, which can negatively affect their
emotions and motivation. Here, we show that individuals with a self-reported
diagnosis of depression on social media express higher levels of distorted
thinking than a random sample. Some types of distorted thinking were found to
be more than twice as prevalent in our depressed cohort, in particular
Personalizing and Emotional Reasoning. This effect is specific to the distorted
content of the expression and can not be explained by the presence of specific
topics, sentiment, or first-person pronouns. Our results point towards the
detection, and possibly mitigation, of patterns of online language that are
generally deemed depressogenic. They may also provide insight into recent
observations that social media usage can have a negative impact on mental
health.
