Acta anaesthesiologica ScandinavicaSep 9, 2005

Is stress hormone release during surgery linked to thinking problems after surgery?

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Updated Apr 2, 2026

Abstract

Salivary cortisol concentrations increased significantly after surgery, with 18.8% of patients exhibiting post-operative cognitive dysfunction (POCD) at one week.

POCD was observed in 15.2% of patients three months after surgery.
Patients with POCD at one week had higher pre-operative morning to afternoon cortisol ratios (2.8) compared to those without POCD (2.7).
Post-operative morning to afternoon cortisol ratios decreased significantly to 1.9 and 1.6 at one week for patients with and without POCD, respectively.
A persistent flattening of the morning to afternoon cortisol ratio was significantly associated with POCD at one week.
Circadian rhythm disturbance or metabolic stress may play a role in the development of cognitive dysfunction following major surgery.

Simplified

BACKGROUND: The pattern of cortisol secretion is influenced by surgery. As cortisol can adversely affect neuronal function, this may be an important factor in the development of post-operative cognitive dysfunction (POCD). We hypothesized that the incidence of POCD would be related to changes in cortisol level.

METHODS: We studied 187 patients aged over 60 years undergoing major non-cardiac surgery with general or regional anaesthesia. Saliva cortisol levels were measured pre-operatively and at 1 day, 7 days and 3 months post-operatively in the morning (08.00 h) and in the afternoon (16.00 h) using salivettes. Cognitive function was assessed pre-operatively, on day 7 and at 3 months using four neuropsychological tests. POCD was defined as a combined Z score of greater than 1.96.

RESULTS: After surgery, salivary cortisol concentrations increased significantly. POCD was detected in 18.8% of subjects at 1 week and in 15.2% after 3 months. The pre-operative ratios between the morning and afternoon cortisol concentrations (am/pm ratios) were 2.8 and 2.7 in patients with POCD at 1 week vs. those without POCD at 1 week, respectively. The am/pm ratios decreased significantly post-operatively to 1.9 and 1.6 at 1 week, respectively (P = 0.02 for both). In an analysis considering all am/pm ratios, it was found that the persistent flattening in am/pm ratio was significantly related to POCD at 1 week.

CONCLUSION: The pattern of diurnal variation in cortisol level was significantly related to POCD. Thus, circadian rhythm disturbance or metabolic endocrine stress could be an important mechanism in the development of cognitive dysfunction after major surgery.

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Is stress hormone release during surgery linked to thinking problems after surgery?

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