This study failed to replicate the finding of Cotter et al
3 that MDD was associated with reduced BIV. Differences between the study populations or rating methods could be relevant to this discrepancy. The sample in the Cotter et al study was 41% male, whereas all of our subjects were female. Second, in the current study, subjects were matched for reproductive factors, including hormone treatments and cycle phase. Sex and reproductive factors may be relevant in view of the present finding that postmenopausal women showed reduced BIV and the literature on sex differences in HPA axis function.
5 Third, patients were older in the Cotter et al study, and age may have contributed to the reduced response in postmenopausal women in this study. Fourth, all of the patients in this study were psychotropic-free, whereas Cotter et al's patients were all taking antidepressants. Although antidepressants have been reported to increase, not decrease, GR function,
2 it is possible that BIV may be influenced by effects of antidepressants on vascular tone downstream from GRs. For example, glucocorticoids potentiate noradrenaline-induced vasoconstriction,
12 and noradrenergic function may be increased by antidepressants.
13 Fifth, the subjects in this study were moderately depressed outpatients recruited via public notices, whereas Cotter et al studied inpatients with major depression, half of whom were taking lithium. This suggests that factors such as severity, treatment-seeking, treatment-resistance, admission to hospital or suicide risk may be relevant, particularly because we excluded patients needing urgent treatment. Psychotically depressed patients, who may have more frequent or marked HPA axis abnormalities,
14 were excluded from both studies. In the current study, patients with PTSD were excluded because of evidence that BIV may be increased in this population.
15 In most of the patients in the Cotter et al study, but none in this study, blanching was undetectable at 3–10 μg/mL. A lower threshold of the current raters for detecting faint blanching could produce this result, but this would not explain the lack of group differences across the whole range of beclomethasone concentrations and on the “median BIV scores.”
Visual-ratings are the most sensitive method to detect faint steroid-induced vasoconstriction and are reliable within laboratories if consistent conditions and trained raters are used.
16,17 However, comparisons between laboratories cannot be readily made without standardization. There is good evidence that BIV is mediated by GRs. First, steroid-induced vasoconstriction has shown clear dose–response relations,
18 and vasoconstrictive potency is associated with clinical efficacy in the treatment of psoriasis, allergy and asthma.
19,20,21 Second, vasoconstriction was inhibited by the nonselective GR antagonists, progesterone, deoxycorticosterone and mifepristone (RU486).
8,22,23 Third, pharmacological blockade of the intracellular metabolism of cortisol by 11-β-hydroxysteroid dehydrogenase (11-β-HSD), using glycyrrhetinic acid, increased cortisol-induced vasoconstriction.
24 11-β-HSD does not metabolize beclomethasone, and so differences in 11-β-HSD would not contribute directly to differences in BIV.
25 Fourth, budesonide-induced vasoconstriction is influenced by genetic variants of GRs in healthy subjects
26 that are also associated with risks for glucocorticoid-related disorders, including familial hypertension, hyperinsulinemia and abdominal obesity.
27,28,29 Fifth, direct studies of BIV have also shown an association with familial hypertension and hyperinsulinemia
30 and with clinical resistance to steroids in the treatment of asthma.
8 These data also suggest that although GRs are differentially regulated in different tissues, alterations in GRs or in post-receptor mechanisms might exert effects across multiple tissues.
There was a mild increase in waking cortisol in patients compared with controls. Although this was not significant with 2-tailed tests selected a priori, it might be argued that 1-tailed tests would have been appropriate on the basis of prior evidence for cortisol hypersecretion in depression, although this may not be as common in outpatient or community populations as in patients in hospital.
1,2,30 Waking cortisol was not correlated with BIV. Afternoon salivary cortisol and BIV were correlated, but in the opposite direction to that predicted for receptor down-regulation. This analysis was not the primary objective of the study and was uncorrected for multiple comparisons. The sample was small, and the timing of the saliva collection and control of the subjects' preceding activities were not as rigorous for the afternoon sample as for the waking sample.
The possibility that decreased BIV might be associated with more marked cortisol hypersecretion requires further study. Steroid-resistant asthma patients have shown lower BIV than steroid-sensitive patients taking long-term prednisone,
8 and BIV was not correlated with plasma cortisol in hypertension,
31 suggesting that reduced BIV may occur as a result of mechanisms other than GR down-regulation. In patients with MDD, impaired GR function may be a more consistent abnormality than reduced GR binding in peripheral blood cells.
32In conclusion, the present study did not find the predicted reduction in BIV in unmedicated patients with MDD, despite mild cortisol hypersecretion compared with the controls. Recent findings in PTSD
15 and marked differences between the samples of patients with MDD studied to date suggest that further research is warranted. Although such samples may be difficult to recruit, MDD patients who are unmedicated, but also have severe, chronic, resistant depression may need to be studied.