Evaluation of time memory in acutely depressed patients, manic patients, and healthy controls using a time reproduction task.

Patients with affective disorders have often been reported to experience subjective changes in how they perceive the flow of time. Time reproduction tasks provide information about the memory component of time perception and are thought to remain unaffected by pulse rate disturbances in the pacemaker of the internal clock. In our study, 30 patients with acute depression, 30 patients with acute mania, and 30 healthy subjects of all age groups were presented with a time reproduction task. Participants were asked to observe a stimulus presented on a computer screen for a certain length of time and, subsequently, to reproduce the stimulus for a similar length of time by pressing the space bar on the computer keyboard. Stimuli were presented to each subject for 1, 6, and 37s. On average, the time intervals reproduced by manic patients were shorter than those reproduced by depressed patients. Manic patients reproduced the short time interval (6s) correctly, but under-reproduced the long time interval (37s, P<0.001). Depressed patients correctly reproduced the long time interval, but over-reproduced the short time interval (P<0.001). Remembering time intervals as having been longer than they actually were may lead to a slowed experience of time, as has been described in depressed patients; precisely the converse seems to apply to manic patients.