Cortisol responses to serial MRI scans in healthy adults and in depression.

Magnetic resonance imaging (MRI) scans are a novel environment for most participants. The hypothalamic-pituitary-adrenal (HPA) axis modulates neurohormonal responses to novel and stressful experiences. We sought to examine the neurohormonal responses to MRI scans with the measurement of salivary cortisol. We examined: (1) acute effects of MRI scans by acquiring cortisol measurements immediately preceding and following the scan in comparison with basal cortisol levels, and (2) effects of novelty by measuring cortisol during repeated MRI scans in the same subjects. We examined these effects in two groups of subjects: healthy individuals (n=27, mean age 41.6 years) and patients with depression (n=24, mean age 40.0 years). Both groups showed elevated cortisol levels immediately preceding the MRI scan, particularly for the initial MRI scan, which normalised after the follow up MRI scans as compared with mean basal cortisol levels. There were no significant differences in the acute or mean basal cortisol levels between the groups. In summary, the MRI experience is stressful, particularly for the initial scan, but the stress response is reduced with subsequent scans.