A longitudinal study of time estimation in psychotic disorders.

5 healthy subjects and 9 patients with hospital diagnoses of schizophrenia were studied by means of repeated measurements of time estimation (production method) during a 1- to 2-yr period. The healthy subjects exhibited moderate variability in their time estimations and tended to over- or under-estimate somewhat. Both over- and under-estimation were also found among patients, but the patients were often more variable in their estimations and in some cases deviated more from the correct estimation than the healthy subjects. Two patients were decided under-estimators. They were both young, subchronic schizophrenics. Chronic schizophrenic patients tended to over-estimate time, but the amount of over-estimation had no noticeable correlation to the degree of clinical disturbance. Two patients gradually changed from under- to over-estimation during the observation period. One patient was evidently misdiagnosed. He suffered from a bipolar affective disorder, and his time estimations seemed to depend on his clinical state during the course of the disorder. The results are discussed in the context of earlier findings and physiological disturbances in chronic schizophrenia.