Cognitive functioning and cortisol suppression in recurrent major depression.

Abstract

Major Depressive Disorder (MDD) is often associated with high levels of stress and disturbances in the hypothalamic-pituitary-adrenal (HPA) system, yielding high levels of cortisol in addition to cognitive dysfunction. The aim of the present study was to examine the relation between cortisol levels after the dexamethasone suppression test and cognitive function in recurrent unipolar MDD patients. Twenty-four patients meeting the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.) criteria for a recurrent MDD diagnosis were included in the study. The control group was matched for age, sex, and education level. Cortisol was measured in saliva collected with Salivette sampling devices. Saliva samples were collected four times during a 24-hr period over two consecutive days: at awakening, after 45 min, after 7 hr, and at 11:00 p.m. One milligram of dexamethasone was given on Day 1 at 11:00 p.m. The neuropsychological test battery consisted of standardized tests measuring cognitive functioning within verbal and visual memory, as well as executive functioning. Cortisol levels did not differ between patients and controls on Day 1. Cortisol levels in patients were higher than in controls at awakening on Day 2 (D2S1), after dexamethasone administration the previous evening. All significant correlations between cognitive measures and cortisol at D2S1 were negative, indicating that low suppression after intake of dexamethasone is related to poor cognitive functioning. Significant relations were found in three of the cognitive tests measuring verbal memory, semantic fluency, and inhibition. The present findings indicate that dysregulation of the HPA-axis is related to poor verbal memory functioning. There was no firm evidence that abnormal cortisol levels were associated with inhibition difficulties.