I have been doing a lot of reading lately regarding inflammation and the brain. It is a huge interest of mine seeing as my neurological and psychiatric symptoms appear to be highly intertwined with the functioning of my immune system. The more reading I do on this topic, the more I come to believe that a very high percentage (possibly the majority) of psychiatric cases are actually inflammatory conditions.
Inflammation and immune responses have been associated with many mental health conditions such as Depression, Schizophrenia, and Bipolar Disorder.
A 2016 study found that measurements Interleukin 6 in peripheral blood mononuclear cells were reliable in distinguishing subjects with Schizophrenia vs those without. Higher levels of Interleukin 6 mRNA were found in those who developed Schizophrenia at a younger age. Interleukin 6 plays a role in inflammation and responses to infections. These findings suggest that inflammation and problems with the immune system may play a role in Schizophrenia. (1)
A 2007 study autopsied the brains of 55 Schizophrenic individuals and 55 control subjects. It found that individuals with Schizophrenia had an upregulation in genes associated with immune responses. This shows that there is evidence of alterations in inflammation related pathways in Schizophrenia. The authors state that these findings encourage research to be done on whether anti-inflammatories could be used in combination with antipsychotics for more effective Schizophrenia management. (2)
A study from 2018 states that over the past 30 years, there has been mounting evidence for an immunological component to Schizophrenia, including dysregulated cytokines (inflammatory markers) and activation of microglia (the main form of immune defense in the central nervous system). The study consisted of 69 patients having their first episode of a Schizophrenia spectrum condition, 16 people in their first episode of Bipolar Disorder associated with psychosis, and 53 healthy control subjects.
The study found that various Interleukins were raised in the blood plasma of patients with Schizophrenia. Patients with Bipolar Disorder had higher levels of IL-10 in their blood plasma compared to healthy controls. The study concludes that pro-inflammatory cytokines may be strongly involved in Schizophrenia, as there is evidence of cytokine associated reductions of grey matter in the brain. (3)
A literature review from September 2013 points out that depression is linked with chronic inflammation and the activation of immunity. It states that remission of depression is associated with inflammatory markers going back to normal levels. The literature review states that animal models have shown that childhood trauma can contribute to poor functioning of the immune system. It also points out that psychosocial stress is associated with lower levels of inflammation reducing compounds in the body. It lists obesity, vitamin D deficiency, diet, atopic disorders, trauma and stress as potential contributing factors. (4)
A 2014 article in the "Journal of Neuroinflammation" states that "Depression and cognitive impairment are two such disorders which may share a closely linked inflammatory etiology". It states that the immune system may be a therapeutic target for the treatment of these issues. It also points out that although we shouldn't dismiss the effectiveness of current anti-depressant medications used, alternative interventions which address the inflammatory basis of these disorders should be considered. It explains that although diet changes and supplements with proven anti-inflammatory properties are unlikely to provide immediate relief, they may lead to a more permanent resolution of the struggles and may reduce the impact that medication side-effects may have on people. (5)
A review published in "The Journal Of Neuroinflammation" in 2019 concludes that there is a strong association between relapsing Major Depressive Disorder and inflammatory processes. It states that chronic inflammation may trigger dysfunction in the brains ability to use Serotonin, Dopamine, and Norepinephrine in a typical manner. It points out that studies have shown how people with Major Depressive Disorder tend to have higher levels of pro-inflammatory cytokines, and it states that an increase in inflammation may contribute to treatment resistant depression. It talks about how there is a large amount of evidence showing that increased inflammation and hyperactivity of the HPA axis are some of the most common physical findings in a subset of individuals with MDD.(6)
Older Discoveries Regarding Psychosis:
The link between the immune system and psychosis has been commented on many times throughout history. In 1926, an American psychiatrist called Dr Karl Menninger documented over 100 cases of psychosis triggered by the Flu. In 1937, Lehman Facius found that patients diagnosed with Schizophrenia had autoantibodies in their cerebrospinal fluid. These autoantibodies attacked brain tissue. Facius theorized that there may be an autoimmune component to Schizophrenia. (7,8)
What Could We Take From This Information?
We should focus on finding out what the root triggers are for inflammation in each individual case. It is possible that inflammation triggers may include infections, food sensitivities / dietary allergens, stress and trauma, mould, pollen and more. Finding and eliminating or addressing root triggers may reduce troublesome symptoms in some individuals.
It really shows how mental illness isn't a choice and is not something that a person chooses or can just "snap out of".
The mind and body are not separate at all. If you look after your body it may also be looking after your mind.
It tells us that certain mental health clinics may be able to offer a higher level of care by assessing patients for underlying inflammatory issues and try to pinpoint any contributing factors which may be fueling this inflammation.
Chase, K.A., Cone, J.J., Rosen, C. and Sharma, R.P. (2016). The value of interleukin 6 as a peripheral diagnostic marker in schizophrenia. BMC Psychiatry, [online] 16. doi:10.1186/s12888-016-0866-x. This study is under the Creative Commons Attribution 4.0 International License. https://creativecommons.org/licenses/by/4.0/ Edits were made to avoid plagiarism.
Saetre, P., Emilsson, L., Axelsson, E., Kreuger, J., Lindholm, E. and Jazin, E. (2007). Inflammation-related genes up-regulated in schizophrenia brains. BMC Psychiatry, 7(1). doi:10.1186/1471-244x-7-46. (2)
Lesh, T.A., Careaga, M., Rose, D.R., McAllister, A.K., Van de Water, J., Carter, C.S. and Ashwood, P. (2018). Cytokine alterations in first-episode schizophrenia and bipolar disorder: relationships to brain structure and symptoms. Journal of Neuroinflammation, [online] 15(1). doi:10.1186/s12974-018-1197-2. This study is under the Creative Commons Attribution 4.0 International License. https://creativecommons.org/licenses/by/4.0/ Changes were made to prevent plagiarism.
Berk, M., Williams, L.J., Jacka, F.N., O’Neil, A., Pasco, J.A., Moylan, S., Allen, N.B., Stuart, A.L., Hayley, A.C., Byrne, M.L. and Maes, M. (2013). So depression is an inflammatory disease, but where does the inflammation come from? BMC Medicine, [online] 11(1). doi:10.1186/1741-7015-11-200.
Allison, D.J. and Ditor, D.S. (2014). The common inflammatory etiology of depression and cognitive impairment: a therapeutic target. Journal of Neuroinflammation, 11(1). doi:10.1186/s12974-014-0151-1.
Liu, C.-H., Zhang, G.-Z., Li, B., Li, M., Woelfer, M., Walter, M. and Wang, L. (2019). Role of inflammation in depression relapse. Journal of Neuroinflammation, 16(1). doi:10.1186/s12974-019-1475-7. This article is under the Creative Commons Attribution 4.0 International License. https://creativecommons.org/licenses/by/4.0. Changes were made to prevent plagiarism.
Mooneyham, G. (2018). Evaluation and Management of Autoimmune Brain Disorders: A Psychiatry Perspective. [online] Available at: https://www.ncpsychiatry.org/assets/2018AnnualMeeting/BW/Evaluation%20and%20Management%20-%20GenaLynne%20Mooneyham.pdf [Accessed 13 Jul. 2022].
Johnsen, E. (2018). Immunologiske forhold ved psykoselidelser - muligheter for ny behandling? [online] Available at: https://akuttpsykiatri.no/wp-content/uploads/2018/02/1405-Johnsen-Akuttpsykiatrikonf2018Immun_EJ.pdf.
Disclaimer: This is for educational purposes only. If you would like to learn more then I recommend doing your own research on the topic. I do not own any of the content in the reference links provided above, I am just giving credit to the authors were I learnt this information.