Comment on “Psychoneuroimmunology of mental disorders”

The area of psychoneuroimmunology has received increasing interest during the last generation. A major reason for this is due to our improved understanding of the dynamics between visceral responses and affective states. Saying this, our knowledge of the complexity of these processes is incomplete. A significant finding in psychoneuroimmunology is the role of inflammatory processes in mental disorders. This is a very broad topic which has been discussed by Soria et al.¹ Firstly, I commend the authors for focussing on the diagnostic and therapeutic aspects of mental disorders in relation to psychoneuroimmunology. The authors provide a concise and insightful overview of major mental disorders and the involvement of cytokine activity in their etiology. As the authors note, previous studies draw a strong correlation between cytokine induced inflammation and schizophrenia, depression, bi-polar disorder and PTSD.

In their discussion the authors make two comments which I will expand on. Firstly, is the need to expand research into inflammatory markers beyond the current variables. I would also include ethnicity, exposure to psycho-physical trauma and enteric gut microbiome (EGM) makeup. These are also important variables in inflammation and mental disorders. For example, some studies indicate that gut bacteria play a key role in modulating endocrine function and stress response. Furthermore, various gut bacterial species are vital in neurotransmitter production,² and neurotrophin modulation during neo-natal development.³ It has been shown how administration of the bacterial species Bifidobacteria infantis into immature rats reduces pro-inflammatory response of IL-6, TNF-α, and IFN-γ cytokines.⁴ Several gut bacterial species may even create neurochemicals whose molecular structure are analogous to those produced by the host’s CNS. Consequently, we need to further explore whether EGM engineered biomimicry may contribute to mental disorders.

Moreover, the authors are rightly concerned on the use of anti-inflammatory drugs in treating severe mental disorders. So far studies on anti-inflammatory drugs as a potential treatment have been small and inconclusive. We need to be cautious. Anti-inflammatory drugs have not been authorised as a viable alternative to anti-depressant or anti-psychotic drugs. However, this may not deter some physicians from prescribing them. In developing countries where I have lived, many physicians are reluctant to prescribe anti-depressant or anti-psychotic drugs to patients due to their expense. In contrast, anti-inflammatory drugs are relatively cheaper. This may prove to be a decisive factor in prescribing their use.

Funding

The author received no funding for writing this letter.