***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Dysfunction in the hypothalamic-pituitary-adrenal ( HPA ) axis has been proposed as a biological endophenotype for affective disorders . In the present study the hypothesis that a high genetic liability to affective disorder is associated with higher cortisol levels was tested in a cross-sectional high-risk study . Healthy monozygotic ( MZ ) and dizygotic ( DZ ) twins with ( High-Risk twins ) and without ( Low-Risk twins ) a co-twin history of affective disorder were identified through nationwide registers .  Awakening and evening salivary cortisol levels  were compared between the 190 High- and Low-Risk twins . The 109 High-Risk twins had significantly higher evening cortisol levels than the 81 Low-Risk MZ twins , also after adjustment for age , sex , and the level of sub clinical depressive symptoms . No significant difference was found in awakening cortisol levels between High-Risk and Low-Risk twins . In conclusion , a high genetic liability to affective disorder was associated with a higher evening cortisol level , but not with awakening cortisol level . Future prospect i ve family , high-risk and twin studies are needed to decide whether abnormalities in the HPA axis can be identified as an endophenotype of affective disorder BACKGROUND Persistent impairments in neurocognitive function have been described in patients with bipolar disorder whose disease is in remission . However , method ological issues such as the effect of residual mood symptoms and hypercortisolaemia may confound such studies . AIMS To assess neurocognitive functioning in prospect ively verified euthymic patients with bipolar disorder . METHOD Sixty-three patients with bipolar disorder and a matched control group completed a comprehensive neurocognitive test battery .  Euthymia was confirmed in the patient group by prospect i ve clinical ratings over 1 month prior to testing . Saliva sample s were collected to profile basal cortisol secretion . RESULTS Patients were significantly impaired across a broad range of cognitive domains . Across the domains tested , clinical ly significant impairment was observed in 3 % to 42 % of patients . Deficits were not causally associated with residual mood symptoms or hypercortisolaemia . CONCLUSIONS Neurocognitive impairment persists in patients whose bipolar disorder is in remission . This may represent a trait abnormality and be a marker of underlying neurobiological dysfunction Rationale Several previous neuroendocrine studies have demonstrated reduced 5-HT1A receptor function in major depressive disorder ( MDD ) . However , hypercortisolaemia or previous drug treatment may have been significant confounds . Objectives To replicate previous studies in subjects with MDD who had been drug free for at least 8 weeks and to relate the findings to measures of HPA axis function . Methods Hormonal responses to l-tryptophan infusion  were measured in patients with MDD ( n=20 ) and healthy controls ( n=20 ) .  Basal salivary cortisol and DHEA were also profiled . Results No attenuation of 5-HT1A receptor-dependent neuroendocrine responses ( growth hormone , prolactin ) was observed in patients with MDD . The prolactin response to l-tryptophan  was significantly greater in MDD patients than in healthy controls ( P=0.008 ) . There was a significant negative correlation between prolactin response and basal salivary cortisol secretion over the 3 days prior to the test . Conclusions These data do not support previous findings of reduced 5-HT1A function in MDD and suggest that hypercortisolaemia or psychotropic medication may have accounted for the attenuation . Basal cortisol , DHEA and the cortisol-DHEA ratio did not differ between patients and controls , and all patients were psychotropic medication-free . The greater prolactin response to l-tryptophan infusion in depressed subjects may be the result of an increase in dopamine receptor sensitivity , secondary to reduced dopamine levels Rationale Patients with major depression show hypothalamic – pituitary – adrenal ( HPA ) axis hyperactivity , but the mechanisms underlying this abnormality are still unclear . Objectives We have compared two synthetic glucorticoids , dexamethasone and prednisolone , in their ability to suppress the hypothalamic – pituitary – adrenal ( HPA ) axis in depressed patients .  Dexamethasone probes glucocorticoid receptor ( GR ) function , while prednisolone probes both GR and mineralocorticoid receptor ( MR ) function . Material s and methods We used a single-blind , repeated-measure design . We administered placebo , prednisolone ( 5 mg ) or dexamethasone ( 0.5 mg ) , at 22:00 , to 18 severe , treatment-resistant depressed in patients ( 15 of them with a history of childhood trauma ) and 14 healthy volunteers . On the following days , we collected salivary cortisol from 9:00 to 22:00 . Results Depressed patients had higher salivary cortisol levels compared with controls , at baseline and after both prednisolone and dexamethasone ( p<0.001 ) . Consistent with previous studies , depressed in patients showed impaired suppression by dexamethasone :  based on the analysis of the areas under the curve ( AUCs ) , suppression by  dexamethasone ( 0.5 mg ) was −85 % in controls vs −46 % in depressed patients ( p=0.018 ) . However , the same depressed patients showed normal suppression  by prednisolone ( 5 mg ) : suppression was −41 % in controls and −36 % in depressed patients ( p=0.6 ) . Conclusions We suggest that the additional effects of prednisolone on the MR explain the different responses to these glucocorticoids in the same depressed patients Daily activities ( zeitgebers ) such as waking , eating , and exercising , done alone or in the presence of others , may help to entrain biological rhythms . To examine whether the relationship between zeitgebers and biological rhythms is altered in depression , this study tracked daily activity and cortisol secretion in 50 depressed and 50 control participants using a daily diary methodology . The groups reported similar levels of regular daily activities . Among control participants , regular daily activities were associated with a normative decline in cortisol secretion . Among depressed participants , daily activities and cortisol secretion were unrelated , consistent with the hypothesis that these activities are less able to entrain diurnal rhythms . This lack of social entrainment may underlie some of the circadian disturbances in depression 
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Further , in meta-regression analyses higher intra-assay coefficients of variation in cortisol kits ( p=0.07 ) and mean age ( p=0.08 ) were associated with a higher mean difference of morning salivary cortisol between depressed and controls , while gender and depression severity were not .
Based on the available studies there is not firm evidence for a difference of salivary cortisol in depressed patients and control persons and salivary cortisol is unable to discriminate between persons with and without depression