Abstract
Across health research, drawing on accounts from people with lived experience is often promoted as a shift away from epistemic injustice wherein the knowledge of the marginalised is ignored/silenced. Paradoxically for people with mental distress who are given a diagnostic label, aspects of their accounts may actually be foregrounded to categorise them with mental illness/disorder. In doing this, their sense of reality (e.g., ontological experiences) can be judged to be significantly different from other people in addition to their epistemic knowledge and understanding. This points to issues of ontological differences between lived experiencers of various forms of mental distress that need deeper consideration in mental health research and practice, alongside the ongoing work on epistemic considerations. Experiencing serious mental distress can include a loss of trust in one's sensory/perceptual signals which complicates how one makes sense of experience and knowledge. The complexities around these processes is at odds with the more straightforward ideas about testimonial accuracy and speaker credibility that underpin epistemic knowledge goals. This review outlines often-overlooked issues related to ontological differences between people in the context of mental health and offers suggestions for the future.