Journal of affective disorders
-
The neurodegeneration hypothesis proposed major depression as a consequence of the imbalance between neuroprotective and neurodegenerative metabolites in the kynurenine pathway. To test the hypothesis, plasma tryptophan and kynurenine pathway metabolites were studied in 58 patients with major depression and 189 normal controls. ⋯ The neuroprotective ratio did not change after treatment in those with repeated episodes of depression but it increased significantly (p=0.044) in those with first episodes. The results suggested that the reduction in neuroprotective markers, which indicated an impaired neuroprotection, might play an important role in pathophysiology of major depression.
-
Functional neuroimaging research indicates that depression, and treatment, are associated with neurobiological changes. Changes associated with natural recovery or the placebo effect are unknown. The aim of this study is to assess whether the placebo effect in depression is associated with specific functional neuroimaging changes. ⋯ Recovery from depression in placebo groups correlates with changes in frontal and cingulate cortical activity, although these may also be found in recovery without treatment. It is also speculated that antidepressant treatment delay relates to 'counterbalancing' of an advantageous placebo effect with a disadvantageous initial drug effect.