It is unknown whether HPA-axis dysfunction is present in patients with mild cognitive impairment (MCI). The aim of the present study was to investigate whether cortisol levels are elevated among patients with MCI and/or whether the individuals have adequate feedback control of their HPA axis.
27 patients with MCI and 15 healthy controls were included in the study. Saliva samplings were performed 5 times a day before intake of 0.5 mg dexamethasone, and 5 times a day after intake of dexamethasone, respectively.
Significantly higher cortisol levels were found 15 min after awakening among patients with MCI in comparison with the controls, both before and after dexamethasone administration (p<0.05). Also, the ratio between cortisol at awakening time and 15 min after awakening was lower in the patient group after dexamethasone administration (p<0.05). There were no significant differences in basal cortisol levels before or after dexamethasone between groups.
The results indicate that there is an HPA-axis disturbance, with normal basal cortisol levels and increased awakening response among patients with MCI. The dissociation between basal values and the awakening response may be of pathophysiological importance for the cognitive impairment.