We read with much interest the paper by O'Dwyer & Marks (Reference O'Dwyer and Marks2000), and think that the case vignettes reported by the authors fit perfectly with Insel & Akiskal's (Reference Insel and Akiskal1986) model that considers obsessive-compulsive disorder as a disorder that can develop along a continuum of insight. Therefore, the primary problem is not the boundaries between obsessive-compulsive disorder (or anorexia, or body dysmorphic disorder) and psychosis, but rather at which point insight is lost and the disorder under consideration becomes a frankly psychotic one. If one considers insight as a dimension spanning from normality to the most severe psychiatric conditions, then it will not be difficult to posit several psychiatric disorders along it, with all possible heterogenous combinations. The model becomes even more comprehensive if we add the ‘uncertainty/certainty’ dimension, so that prevalent ideations, and thus ‘normal’ conditions, can also be accommodated (Reference Marazziti, Akiskal and RossiMarazziti et al, 1999). Thus, insight can be considered to be intertwined with several other dimensions, yet to be identified, and can become disturbed when these other dimensions are altered. In our opinion, therefore, insight is a phenomenon that is only apparently heterogenous, and in fact is strictly related to other variables and/or clinical core features, so that it may well respond to serotonergic drugs and behavioural therapy, as underlined by O'Dwyer & Marks. The response of insight to various drugs may depend on how close are the links with the other dimension primarily disturbed (e.g. affect; certainty/uncertainty; anxiety). Naturally, these considerations demand new operational criteria that should complete, if not replace, current diagnostic criteria.