Table 2c. Differential biological mechanisms in subtypes of depression—psychotic vs non-psychotic.
| Authors | Objective | Design/sample | Subjects | Procedure | Depressive subtypes | Results |
|---|---|---|---|---|---|---|
| Nelson and Davis78 | To perform a meta-analysis of DST studies published before 1997 | Meta-analysis of cross-sectional studies | 708 non-psychotic, 276 psychotic, 662 MMD, 617 NMMD | Meta-analysis | MMD, NMMD, psychotic/non-psychotic | Psychotic: OR of DST non-suppression in psychotic patients: 3.0 (95% CI, 2.2–4.1). Effect size did not differ significantly between studies (P=0.58) Melancholic: OR of DST non-suppression in MMD patients: 2.0 (95% CI, 1.5–2.6) Effect size varied significantly between studies (P<0.001). No effect size for MMD when adjusted for inpatient/outpatient status. |
| Pivac et al.89 | Examine relationships between plasma cortisol and platelet 5-HT concentrations in depressives | Prospective/clinical | 78 inpatients with recurrent unipolar depression | Depression assessment unclear. DST administered. Platelet 5-HT and cortisol levels assessed next day | Psychotic/ non-psychotic | Psychotic and non-psychotic MDD had ↑ cortisol than controls. Platelet 5-HT significantly different between groups and ↑ in psychotics than non-psychotics and controls. Non-psychotics had ↓ 5-HT than controls. Significantly more DST suppressors in non-psychotic than psychotic subgroup |
| Posener et al.94 | Examine HPA axis abnormalities in psychotic and non-psychotic depressed patients by intensive (hourly) cortisol and ACTH monitoring | Cross-sectional/clinical | 11 psychotic, 38 non-psychotic, 33 controls | SCID, HDRS, BPRS, CGI assessed depression. Hourly serum cortisol and ACTH | Psychotic/ non-psychotic | Cortisol amplitude was lower in the non-psychotic group relative to controls (P=0.02). No significant difference for psychotic group relative to controls or non-psychotics. 24 h mean ACTH was significantly higher in psychotic than non-psychotic depressed patients (P=0.03). |
| Belanoff et al.93 | To examine the association between cortisol levels and cognitive changes in psychotic major depression | Cross-sectional/clinical | 10 psychotic, 17 non-psychotic, 10 controls | HDRS assessed depression. Half-hourly serum cortisol | Psychotic/ non-psychotic | Non-psychotic and control subject demonstrated decreasing cortisol over the course of the afternoon. Psychotic major depression subjects demonstrated stable (and significantly higher P=0.004) cortisol over the course of the afternoon. |
| Cubells et al.95 | To examine for association between plasma dopamine β-hydroxylase activity in psychotic major depression and genotypes | Cross-sectional/clinical | 33 psychotic, 45 non-psychotic | SCID or SADS assessed depression | Psychotic/ non-psychotic | Plasma dopamine β-hydroxylase activity was significantly lower in the group with psychotic features compared with non-psychotic depression (P=0.007). Dopamine β-hydroxylase activity was associated with the C-1021T genotype, however, this did not account for the differences between groups. |
| Gomez et al.91 | Examine the association between serum cortisol/ACTH levels and neuropsychological indices in psychotic major depression | Cross-sectional/clinical | 29 psychotic, 24 non-psychotic, 26 controls | SCID, HDRS, BPRS assessed depression | Psychotic/ non-psychotic | Psychotic depression was associated with elevated mean cortisol in the measured time period relative to non-psychotic depression and controls (P<0.05). Cortisol appeared to partially mediate the relationship between psychotic depression and impairment of neuropsychological indices—particularly verbal memory and working memory. No significant differences between groups in ACTH. Sparse, inconsistent associations with neuropsychological indices. |
| Keller et al.92 | Examine circadian cortisol/ACTH levels in psychotic major depression | Cross-sectional/clinical | 29 psychotic, 24 non-psychotic, 26 controls | SCID, HDRS, BPRS assessed depression | Psychotic/ non-psychotic | Psychotic depression associated with higher evening cortisol, and higher cortisol nadir than non-psychotic and controls (P<0.02 and <0.05, respectively). Non-psychotic depression and controls did not differ (P=0.57). |
| Contreras et al.90 | Examine hypothalamus-pituitary hormone responses in psychotic/non-psychotic patients with melancholic major depression | Cross-sectional/clinical | 19 psychotic MMD, 21 non-psychotic MMD | SCID, HDRS assessed depression | Psychotic/ non-psychotic (within MDD subtype) | No significant differences between psychotic and non-psychotic MMD in DST, thyroid stimulating hormone response to thyrotrophin-releasing hormone, or growth hormone response to growth hormone releasing factor. |
Abbreviations: ACTH, adrenocorticotropic hormone; CGI, Clinical Global Impressions Scale; DST, dexamethasone test; HPA, hypothalamic–pituitary–adrenal Axis; 5-HT, 5-hydroxytryptamine receptors; MDD, major depressive disorder; MMD, melancholic major depression; NMMD, non-melancholic major depression; OR, odds ratio; SCID, structured clinical interview for DSM.