No morning cortisol response in patients with severe global amnesia

Activity of the hypothalamus pituitary adrenal (HPA) axis is characterized by a pronounced circadian rhythm. An acute increase in cortisol. levels occurs after awakening in the morning with continuously declining levels over the course of the remaining day. The morning cortisol increase probably reflects an activational response of the HPA axis aimed at preparing the body for the day. Some studies found patterns of enhanced or blunted waking cortisol responses observed under chronic stress, burnout, or post traumatic stress disorder. The present study wanted to characterize the morning cortisol. response and the circadian cortisol day profile in a sample of six mate patients with severe amnesia due to hypoxia, herpes simplex encephalitis or closed head injury. Age and gender matched relatives or friends served as controls. Cortisol was measured from saliva samples collected at home on two consecutive days. The patients were woken up in the morning by their partners or caregivers. The morning cortisol increase typically observed in healthy subjects and also observed in the control group was absent in the amnesic patients. In contrast, a normal circadian day profile was found in the amnesic patients, with a pronounced circadian cortisol decrease. Further studies are needed to understand the neurological or psychological mechanisms leading to a missing morning cortisol response in amnesic patients. (C) 2004 Elsevier Ltd. All rights reserved.