Attentional and motor dysfunction in depression and mania
Although reaction time (RT) slowing in affective disorders is an established finding, very few studies have compared depressives and manics on the same psychomotor task. In addition, although specific motor abnormalities have been found in schizophrenics, most have also been observed in affectively ill patients. A technological advance has allowed a microanalysis of the RT response based on digital sampling of the pressure applied to the RT button. The present study used such an apparatus to compare directly the psychomotor performance of depressed and manic patients with each other and with a group of normal controls. Patients were determined by Research Diagnostic Criteria (RDC) to have a diagnosis of either major depressive episode or a manic episode. Concurrent ratings of psychopathology were made by nurse collaborators using the Brief Psychiatric Rating Scale. The analysis focused on the variables of premotor time, defined as the time between stimulus onset and initiation of response; motor time, defined as the time between response initiation and response completion; and peak force, defined as the maximum force applied by the subject in completing the response. The amount of tremor in the patient's fingers when at rest in between trials was also measured as it was considered an index of the deleterious effects of psychotropic medications on the motor system. Because of age differences between the groups, age was included as covariate in the analysis. No significant differences were found between the affectively ill patients and the controls or between the depressives and the manics on any of the psychomotor measures. There was a difference which approached significance between the manics and depressives on premotor time. Possible reasons for the lack of findings are (a) moderate power in making the comparison between manics and depressives on the premotor measure, (b) comparatively less complexity and increased structure in the current RT apparatus than in previous paradigms, (c) confounding of the effects of age and the cumulative effects of a psychotic illness.
Carpenter, Daniel Clifton, "Attentional and motor dysfunction in depression and mania" (1992). ETD Collection for Fordham University. AAI9313756.