Effects of depressed mood on objective and subjective measures of attention.

People with depression report frequent cognitive failures, but objective measures of cognition show mixed results. Some studies show impairment on effortful tasks. The relationship between subjective and objective cognitive failures was studied in 102 "depressed" or "nondepressed" UK servicemen, grouped by Beck Depression Inventory scores with a cutoff score of 10. Participants were administered cognitive tests including the Sustained Attention to Response Task (SART), a laboratory measure of vigilance that has revealed increased attentional lapses in traumatic brain injury patients. The depressed men made more errors on SART than the nondepressed men (P=0.012) but reported much higher incidences of cognitive failures on a standardized questionnaire (P=0.0001). The depressed men's SART reaction times slowed following an error, a pattern different from that of brain-injured subjects. Nonclinical depressed subjects may respond "catastrophically" to errors, heightening the subjective sense of failure and contributing to the strong relationship between subjectively reported cognitive failures and depression.