Objective: Cognitive impairment is one of the most important causes of disability in depression. There are conflicting results about the nature of cognitive impairment with some studies finding a difference between first episode (FE) and recurrent depression (RD) and a correlation between cognitive impairment and depression severity while others do not. Our aim was to compare cognitive function in FE and RD patients and to see if cognitive impairment is correlated with depression severity and number of depressive episodes.
Method: Unmedicated 33 FE and 37 RD outpatients with no additional Axis I disorder or physical disorder likely to affect cognition were included into the study and cognitive function was evaluated with verbal memory, verbal fluency, Stroop, Benton facial recognition and Boston naming tests.
Results: There were no cognitive differences between FE and RD groups or between RD patients with more or less than 3 depressive episodes. But severely depressed patients had lower naming and immediate memory scores. Depression severity was positively correlated with Stroop color word reading time and negatively correlated with verbal memory learning score. Perseveration scores were positively correlated with total depressive episode duration.
Discussion: Depression severity seems to be more effective on cognitive function than the number of depressive episodes. Results indicate that simple attention, encoding, learning, naming and mental speed is affected negatively from depression severity and cognitive flexibility was negatively affected by total depressive episode duration supporting prefrontal dysfunction hypothesis in depression.
Key words: Depression, cognition, first episode, recurrent
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