Vaughan Bell flags an important definitional shift in the DSM-5 that alters how psychiatrists approach patients’ unusual beliefs:
[M]ental health professionals are often required to decide if someone’s thinking indicates a disturbance in their understanding of the world, and this is where the new DSM-5 definition of a delusion may usher in a quiet revolution in psychiatry. No longer are psychiatrists asked to decide whether the patient has “a false belief based on incorrect inference about external reality that is firmly sustained despite what almost everyone else believes and despite what constitutes incontrovertible and obvious proof or evidence to the contrary”. A wordy and unhelpful definition that has so many logical holes you could drive a herd of unicorns through it.
Instead, the new definition of delusions describes them as fixed beliefs that are unswayed by clear or reasonable contradictory evidence, which are held with great conviction and are likely to share the common themes of psychosis: paranoia, grandiosity, bodily changes and so on. The belief being false is no longer central and this step forward makes it less likely that uncomfortable claims can be dismissed as signs of madness.
The Dish 