Evidence of an early information processing speed deficit in unipolar major depression.
BACKGROUND
Slowing of the speed of information processing has been reported in geriatric depression, but it is not clear if the impairment is present in younger patients, if motor retardation is responsible, or if antidepressant medications play a role.


METHODS
Twenty unmedicated unipolar depressed inpatients were compared with 19 medicated depressed in-patients and 20 age-, sex- and verbal IQ-matched controls on inspection time (IT), a measure of speed of information processing that does not require a speeded motor response. We also examined the relationship between IT and current mood and length of depressive illness.


RESULTS
Unmedicated depressed patients showed slowing of information processing speed when compared to both medicated depressed patients and controls. The latter two groups were not significantly different from each other. Slowing of IT was not associated with current mood, but was negatively correlated with length of illness since first episode. No differences in IT were found between patients receiving medication with anticholinergic effects and patients receiving medication with no anticholinergic effects.


CONCLUSIONS
The findings indicate that unipolar depression is associated with a slowing of speed of information processing in younger patients who have not received antidepressant medication. This does not appear to be a result of motor slowing.
Tsourtos
G
G
Department of Psychiatry, University of Adelaide, South Australia.
Thompson
J C
JC
Stough
C
C
D000328:Adult; D000339:Affect / Q000187:drug effects; D000928:Antidepressive Agents / Q000627:therapeutic use; D001288:Attention / Q000187:drug effects; D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000188:drug therapy / Q000523:psychology; D004193:Discrimination Learning / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010364:Pattern Recognition, Visual / Q000187:drug effects; D011597:Psychomotor Performance / Q000187:drug effects; D011930:Reaction Time; D012858:Size Perception / Q000187:drug effects
D000928:Antidepressive Agents