In other words, reporting current SI within the previous month could be related to biological changes in the brain or could be related to other experiential factors, such as unexpected life events.33 Major depressive disorder is more likely to be present over a longer time period and, as such, be associated with biological changes that may be detectable (such as lower GFAP levels).27 SI was not common in this cohort, with rates ranging from ∼4 to 5% depending on the follow-up timepoint. Here, GFAP is linked to major depressive disorder.