Aim: Translation of a specific instrument to measure psychomotor retardation, the “Widlöcher Retardation Rating Scale” and validation of this Dutch translation (Widlöcher remmingsschaal, WRS). Method: In three separate studies, we studied reliability (n = 26), concurrent and divergent validity (n = 25) and predictive validity (n = 28) of the WRS. In- and outpatients with a depressive disorder or schizophrenia participated, and scores on the WRS were compared with those on the Montgomery Asberg Depression Rating Scale (MADRS) and retardation items of the Comprehensive Psychopathological Rating Scale (CPRS).

Results: The internal consistency was good (Cronbach alpha = 0.86), interrater reliability was sufficient to good, the correlation between the sumscores of both raters was r = 0.84, n = 23, p <0.01 and the kappa's were between 0.23 and 0.80. Convergent and divergent validity showed in comparing the correlation between the sum scores on the WRS and the CPRS retardation items (r = 0.91, n = 25, p < 0.01 ) with the correlation between the sumscores on the WRS and the MADRS (r = 0.40, n = 25, p = 0.1). The decrease of the sum scores on the WRS after two weeks of treatment with antide-pressants predicted remission after six weeks. A subgroup of the patients who were not in remission after six weeks, showed a predominance of retardation signs over mood disturbances. The same clinical picture was seen in a group of patients with a chronic disorder.

Conclusion: De Widlöcher Retardation Rating Scale in this Dutch translation is a usefull instrument to measure psychomotor retardation. The connection between remaining retardation symptoms and longterm prognosis deserves further investigation.