About one in three people with major depression respond poorly to standard antidepressant treatments. This kind of depression is called treatment-resistant depression, and it can lead to long-term disability, financial challenges, and a higher risk of suicide. Psilocybin-a compound found in certain mushrooms-has shown early promise as a new treatment for this difficult-to-treat depression. Scientists believe it works by affecting a specific brain receptor (called 5-HT2A), which helps the brain become more flexible and adaptable. But there's another possible mechanism of psilocybin that hasn't been studied much: its ability to influence the immune system. Recent research suggests that inflammation in the body might play a role in depression, especially when treatments don't work. High levels of certain inflammatory markers (called cytokines) are linked to poor response to antidepressants, while lower levels are tied to feeling better. Psilocybin may help reduce this inflammation, which could be part of why it helps some people feel better. Still, we don't fully understand how a person's inflammation levels before treatment, and how those levels change afterward, relate to how well psilocybin works. Figuring this out could help doctors better match patients to psychedelic therapy and discover new ways to treat depression. In this study, blood samples from a recent study (called the PsiDeR trial) that tested psilocybin in people with treatment-resistant depression will be analyzed. Cytokine levels in these blood samples, as well as levels of another type of molecule linked to inflammation, called mRNA, will be measured.
Chronic and elevated inflammation is associated with depression. Depressed patients tend to have raised inflammatory markers compared to healthy controls, and studies have reported that the greatest elevation is seen in patients with treatment-resistant depression (TRD). Previous studies highlight the bidirectional relationship between inflammation and depression. Elevated pro-inflammatory cytokines are linked to poor antidepressant response, while reductions in these markers are associated with symptom improvement. While neuroinflammation may play a role in the pathophysiology of depression, inflammation is also a causal risk factor for physical illnesses that are often co-morbid with depression, such as cardiovascular disease. As such, targeting inflammation in patients with depression may have significant implications for both their mental and physical health. Psychedelics are emerging as a potential new class of therapeutic agents for psychiatric illness, including depression. It has been suggested that their therapeutic effect may partly be due to reducing inflammation. Psychedelics have been shown reduce markers of inflammation in models of human inflammatory disease, both in vitro and in vivo. While, as might be expected, psilocybin was not found to reduce markers of inflammation in healthy human volunteers, in a clinical sample of people with treatment-resistant depression, use of ayahuasca (containing the psychedelic N,N DMT) resulted in a significant reduction in CRP levels compared to participants given placebo, with the reduction in CRP levels significantly correlated with a reduction in depressive symptoms. Ayahuasca consists of an admixture of multiple different compounds. As such, the relative contribution of the psychedelic to the anti-inflammatory effect that was observed is unknown. The effect of isolated psychedelic compounds such as psilocybin on the systemic inflammatory state of patients, specifically patients with depression, therefore, remains to be investigated. Psilocybin's capacity to reduce inflammation, as evidenced in preclinical models, may be a crucial mechanism underlying its therapeutic effects. Moreover, while it is recognised that baseline inflammation levels can influence the effectiveness of conventional antidepressants, it is unclear whether this is also the case for psilocybin. This study aims to evaluate serum cytokine and inflammatory-related mRNA levels in samples collected from participants with TRD who took part in the (Psi)locybin in (De)pression (R)esistant to Standard Treatments (PsiDeR) Trial, and the relationships between these and psilocybin treatment response. PsiDeR was a randomised, placebo-controlled trial of psilocybin as a treatment for TRD that has now completed.
Study Type
OBSERVATIONAL
Enrollment
46
King's College London Institute of Psychiatry, Psychology and Neuroscience
London, United Kingdom
Linear regression to examine the association between baseline cytokines and depression outcomes at six weeks
Linear regression to examine the association between baseline cytokines and depression outcomes at six weeks
Time frame: Six weeks
Linear regression to examine the association between cytokine level change and depression outcomes at six weeks.
Linear regression to examine the association between cytokine level change and depression outcomes at six weeks.
Time frame: Six weeks
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