Audioverbal cognitive dysfunction in depression. Factors involved.

Abstract

There is increasing evidence suggesting that depression is associated with a certain degree of cognitive dysfunction. However, there is still debate on whether this dysfunction is only substantially associated with the most severe forms of depression, on whether or not it decreases in parallel with clinical response, and on the role played in these changes by psychotropic medications. In order to clarify these questions, we analyzed the performance in several cognitive tasks that involved attention and working memory of 40 untreated subjects with a diagnosis of dysthymia or major depressive disorder without melancholia. The protocol used included three audioverbal tasks: vocal reaction time (VRT), inverse spelling (IS) and text repetition (TR). The protocol was also administered to 20 healthy volunteers that were used as a comparison group. The same battery of assessments was administered 2 months later to all 60 subjects. At the time of the second assessment, patients (but not healthy volunteers) were on antidepressant medication, in accordance with common clinical practice. The authors found a longer VRT in patients versus healthy volunteers at baseline. VRT did not decrease in patients that responded to treatment. However, there was an improvement in VRT in patients that took sertraline (n=16) compared to subjects taking imipramine (n=11). This fact was not attributable to differences in antidepressant response. Performance in the two other tasks was globally worse in the patient group than in the comparison group, and there was also an absence of improvement in the scores of patients who responded to treatment. However, when the sample was stratified by illness duration, individuals with less than 10 years from the first episode of depression showed a decrease in IS errors compared to the healthy volunteers. It is concluded that patients with nonmelancholic depression suffer from cognitive dysfunction, that this dysfunction persists after clinical improvement and that at least attention is influenced by the type of medication taken. Time from onset of the disorder also seems to influence changes in cognitive performance.