Stress of dying is not suppressed by high-dose morphine or by dementia

Hypothalamo-pituitary-adrenal (HPA)-axis activation is a response of the organism to psychological and physical stress, resulting in elevated levels of glucocorticoids, mainly cortisol in humans. In our previous studies we found post-mortem blood and cerebrospinal fluid (CSF) cortisol levels to be up to 20-fold higher than in vivo levels. Since clinical observations point to similar strong elevations of cortisol in fatally ill patients, we suggested that the high post-mortem cortisol levels might be due to the stress during the process of dying. We hypothesized that if the cortisol rise during dying is due to the psychological stress of the impending death, then the rise in cortisol should be inversely proportional to the degree of dementia, and that high-dose morphine giving analgesia, sedation, and sleep would suppress this response. Therefore, we measured the cortisol levels by radioimmunoassay (RIA) in the post-mortem CSF of 85 Alzheimer patients and 52 controls. In addition, post-mortem serum cortisol of 17 subjects from the Alzheimer group and nine from the control group were measured. The Alzheimer patients were subdivided according to their degree of dementia, as scored on the Reisberg Scale, before their death. All groups were further analyzed for the effect of morphine treatment, as well as for the effects of the confounding factors like age, gender, time, and season of death. Alzheimer patients had significantly higher cortisol levels than controls, both in CSF (mean (nmol/l)+/-SEM: 482+/-32 vs 285+/-30, respectively, p<0.001) and in serum (2854+/-279 vs 1533+/-395, p=0.011). Mean CSF cortisol level of the severely demented Alzheimer group was even significantly higher than that of mildly demented group (508+/-35 vs 225+/-65, p=0.024) and controls (p<0.001). Cortisol levels correlated positively with the degree of dementia in the Alzheimer group (r=0.236, p=0.035). High-dose morphine did not cause a suppression of cortisol rise, neither in controls nor in Alzheimer patients. Our results indicate that the extreme elevations of cortisol levels during dying are rather due to the organic stress of the organism than to psychological stress of the patient, and is not suppressed by high-dose morphine.