A final common pathway to hearing voices: examining differences and similarities in clinical and non-clinical individuals

Although auditory verbal hallucinations (AVH) are a cardinal symptom of schizophrenia, they are frequently described on a continuum, ranging from patients diagnosed with a psychotic disorder to non-clinical populations. A key difference between these groups, however, is the absence of additional symptomatology as well as medication use in the group of non-clinical individuals, thus providing an excellent opportunity to study voices in relative isolation. However, this relies on the rather challenging assumption that AVH in clinical and non-clinical individuals can be considered the same phenomenon resulting from a common neurobiological substrate. Studies comparing voices between these groups might provide support for or against this assumption. Furthermore, increasing knowledge about AVH in non-clinical individuals might help eliminate ideas that AVH are always related to a need for care and could hence help to put voices in a more positive light. The aim of this review was therefore to review and summarize studies on AVH in non-clinical individuals with a main focus on the comparison between non-clinical individuals with AVH and individuals diagnosed with a psychotic disorder. Both groups displayed similar brain activation during the experience of AVH, showed aberrant brain connectivity and an increased rate of childhood traumas.