Activity in the hypothalamic-pituitary-adrenal axis and delirium

Glucocorticoid hormones are important for coping with stress but may have d eleterious effects on mood and memory during prolonged excessive secretion. A key abnormality related to cortisol excess in delirium seems to be abnor mal 'shut-off' of the hypothalamic-pituitary-adrenal (HPA) axis tested by t he dexamethasone suppression test. In experimental models, the hippocampal formation is of prime importance for normal HPA axis shut-off. In this brai n area, a close interaction between neurotransmittors, notably acetylcholin e, serotonin and noradrenaline, and glucocorticoid receptors, is present an d possibly relevant for the development of delirium in elderly patients wit h stroke and neurodegenerative brain diseases.