As Zachar et al note, what was originally envisioned was a shift to a "more scientific basis of psychiatric classification" to take account of the aetiology of mental disorders (see eg. previous post). The paper suggests that any hope for a shift from descriptive to aetiologically-based diagnostic criteria had been largely abandoned by the time the workgroups were finally formed in 2008, not least because the human genome project had not produced candidate genes for mental disorders and there was more questioning about what neuroimaging could achieve.
Darrel Regier reports that DSM-5 leaders were not willing to delay publication, even though the National Institute of Mental Health (NIMH) were about to launch its experimental approach that became the Research Domain Criteria (RDoC) (see previous post). This was because of "what amounted to a resurrection of those very aspirations [that had initially motivated DSM-5]". If this was really the case, then DSM-5 had some foresight, as speculation about neural circuits has gone overboard (see previous post) and Thomas Insel, the previous NIMH director, in my view led NIMH completely 'off beam' with RDoC and so-called precision medicine (see another previous post).
The paper suggests any decisions about changes were left to the workgroups. To give more direction to the process, BOT created an oversight committee in summer 2009. New guidelines accepted that “DSM-5 will not ‘in itself’ represent a paradigm shift, nor abandon the categorical system of classification, but will start a process that will lead to more useful ways of classifying and diagnosing disorders”. I’m not convinced it really did so, ending up merely with a tinkering with diagnostic criteria far short of the original misguided intentions. It would have been better if the time had been spent rethinking the basis of psychiatric classification (see eg. previous post).