Objective: Our study aimed to assess the longitudinal change of cognitive functions in depressed patients after a 6-month interval free of mood symptoms.
Methods: In a longitudinal study, 65 patients diagnosed with recurrent major depressive disorder were evaluated twice with neurocognitive tests, during an acute depressed episode and after 6 months of euthymia. The cognitive dimension was assessed with neuropsychological tests of attention and processing speed, memory, verbal fluency, psychomotor speed and executive functions. The severity of depression was evaluated through Hamilton Depression Rating Scale - 17 items. All the results were compared with the outcomes of 35 healthy controls, both in depression and euthymia.
Results: Depressed patients compared to controls displayed significant statistical differences for most cognitive tests applied, verbal and working memory being the most severely impaired. They were still impaired at the second evaluation. Significant differences were noted between the euthymic and control group, too. Between the depression phase and euthymia, patients obtained significant improvement for attention and processing speed, verbal fluency, motor speed and executive functions.
Conclusions: Results from the current study indicate that cognitive impairment is more severe for depressed patients, decreases for euthymic subjects, and lasts longer after depressive symptoms remit.
Keywords: Cognitive impairment; depression; euthymia; major depressive disorder.