Modality shift effect in psychiatric disorders - a new look at an old paradigm.

BACKGROUND

There is a long tradition of reaction time studies in experimental psychopathology. Even though a diminishing interest in this paradigm has been seen over the last years, it is in line with more recent biological approaches to examine psychiatric disorders cross-diagnostically.

METHODS

Patients (n=95) with a positive subtype of schizophrenia (n=22), a negative subtype of schizophrenia (n=18), a full major depressive episode (n=19), a full manic episode (n=16), or a mood disorder in remission (n=20) and subjects with no known psychiatric disorder (n=30), respectively, participated in a computer-based reaction time test consisting of four trials with 55 short visual and auditory stimuli presented in a random sequence. Each participant's median reaction time in milliseconds to light stimuli ipsimodal (light preceded by light) and cross-modal (light preceded by tone) and the difference between the two conditions (i.e. cross-modal retardation (CMR) to light) were recorded. Likewise, the median reaction time to tone stimuli ipsimodal and cross-modal and the difference between the two (CMR to tone) were recorded.

RESULTS

Patient groups performed worse than the control group, with the exception of the group of patients with mood disorders in remission in both CMRs. When comparing patient groups, the schizophrenia negative subtype performed worse than the remission group in both CMRs.

CONCLUSIONS

Our data support newer theories about underlying pathophysiological mechanisms and observable behavioural phenomena occurring across the different diagnostic categories, thereby supporting a dimensional approach in the diagnosis and clinical management.