The link between depression and inflammation

Several studies have described the link between depression and inflammationSince there are not a few patients diagnosed with inflammatory disease who exhibit depressive symptoms.

It’s not that the idea is defended that having inflammation will always lead to depression, but the two conditions have been seen to have a strong comorbidity, suggesting that they have a biological connection in common.

Next, we’ll talk about the theory that tries to explain this phenomenon, as well as delve into the biological causes behind this process.

    The link between depression and inflammation

    It has been shown that patients diagnosed with major depression are more likely to exhibit inflammatory processes. In turn, people who suffer from chronic diseases, in which a high immune response occurs, Are more likely to be diagnosed with a mood disorder.

    Among the diseases in which inflammatory processes occur and in which the greatest relation has been observed with depression, we have, to name a few, diabetes, rheumatoid arthritis, asthma, sclerosis in plaques, cardiovascular problems, chronic pain and psoriasis.

    Below we will look at the main theory that he tried to establish and explain the relationship between the two health issues.

    Theory of the inflamed brain

    This theory has been proposed to explain the relationship between depression, a mental disorder and inflammation, a physiological process.

    Several studies have pointed out that people diagnosed with major depression have higher levels of a factor involved in inflammatory processes, cytokines.

    It seems that cytokines can alter the brain functionally and structurally, Thus inducing changes in both mood and cognitive abilities.

    It has been pointed out that inflammatory processes in Western societies are linked to an unhealthy lifestyle, in particular by relating it to two factors: diet and environmental pollution.

    Others, on the other hand, argue that the cause could be internal, caused by how we react to environmental stressors, with a style of thinking this leads to worry about poorly adaptive form, manifested by physiological symptoms such as inflammation.

    In other words, we are so stressed and depressed that our body reacts physiologically, which causes immune diseases.

    Stressful situations cause the body to release the stress hormone cortisol. In turn, this hormone increases the levels of cytokines in the blood and substances associated with wear and tear at the cellular level, such as nitric oxide.

      The mechanisms that would be at the origin of this link

      The healthy body responds to external pathogens through immune processes. In this way, it activates the cells responsible for defending the human body, preventing pathogens, whether viruses, bacteria or parasites, from doing what they want and achieving their goal: to fall. sick.

      however, the immune process itself involves some wear and tear and temporary discomfort while the body tries to cope with the external threat.

      The inflammatory process is that response to the threat, and it involves some temporary discomfortAs happens when one has a fever or inflammation in any part of his body.

      The assumption behind the idea of ​​the hot brain is that social pressures, insecurities, and any psychological issues can induce this same inflammatory response, as if it were a virus.

      The problem of social pressures are that they are difficult to resolve or alleviate and, if the person copes inappropriately, they subject their brain to constant stress. This causes psychopathology and organic problems.

      Depression and inflammatory biomarkers

      Cytokines, or cytokines, are proteins that are released during the inflammatory process, and they serve to activate the immune system, stimulating it to face external threats.

      As we have seen, one of the inflammatory biomarkers, cytokines, appears in greater amounts in people with depression, which could be the biological link between inflammatory processes and mental health.

      Cytokines and cognitive problems

      Patients with depression have, on average, been shown to have greater cognitive problems than people without a diagnosis.

      The problems become particularly important in areas such as attention, executive functions, memory, in addition to showing other cognitive deficits.

      These problems have been shown to correlate positively with higher levels of cytokines and also with the presence of other factors involved in the inflammatory process.

      Apparently, cytokines and other immunological factors could play a central role in synaptic plasticity and other cellular mechanisms involved in cognition.

      This relationship between neurological inflammation and cognitive dysfunction is proven, especially if a disease such as Parkinson’s disease, Alzheimer’s disease or mild cognitive impairment is taken into account.

      It is quite well known as beta-amyloid plaques, found in various dementias, affect function at the cognitive level and inflammatory processes are also involved, as well as cytokines.

      Thus, neuroinflammatory processes appear to lead to cognitive and behavioral changes through various mechanisms, including changes in gene expression and neuronal functioning.

      Depression in patients with inflammatory diseases

      Inflammation acquires a very important role in various metabolic, neurological and behavioral conditions. It is not uncommon for it to have been associated with depression. Below we will look at several medical issues in which this immune process occurs that may be related to depression.

      Depression in diabetics

      It has long been known that there is a relationship between depression and diabetes.

      There is a high prevalence of people with insulin problems who have symptoms typical of depression.; however, since depression and diabetes are two very common conditions, it is expected that there will be some co-morbidity.

      However, epidemiological studies have shown that the two diseases occur too often together, which has suggested a relationship between sugar levels and the manifestation of depressive symptoms.

      It goes without saying that while well-treated diabetes is not fatal, it is a chronic condition that would cause the newly diagnosed person to go through depression for a period of time.

      What has been seen is that the having high blood sugar is statistically associated with low mood.

      In addition, the lifestyle of many people with depression and diabetes coincides. It is common for both diagnoses to have a profile of someone who eats foods high in sugars and fats, in addition to being sedentary.

      Depression, rheumatoid arthritis and multiple sclerosis

      depression it seems to happen 5 to 10 times more often in people with a serious medical problemJust like diseases such as arthritis or sclerosis, where the person gradually weakens.

      We have seen that about half of people who suffer from multiple sclerosis, either from a biological mechanism of inflammation-depression, or from awareness that their disease is chronic and neurodegenerative, are diagnosed with depression. major.

      In other diseases, also of an inflammatory type, such as rheumatoid arthritis, psoriasis and gastrointestinal diseases such as Crohn’s disease, the ratios range from 13 to 17% of cases of depression.


      From the bibliography consulted, it seems that the link between depression and inflammation is strong, Seen in several medical conditions in which an immunological, metabolic, behavioral and cognitive level affect occurs.

      Depression occurs in a higher percentage in people who have been diagnosed with a disease in which there is endocrine insufficiency, such as diabetes, inflammatory diseases such as arthritis, sclerosis, and gastrointestinal problems.

      However, despite the relationship between the two problems, one has to understand the idea that one will not necessarily generate the other. The reason someone with a chronic illness was diagnosed with depression may be because after being diagnosed with their medical problem, they became depressed because of it, and not as a symptom of the condition. medical.

      Bibliographical references:

      • Amodeo, Giovanni and Trusso, Maria and Fagiolini, Andrea. (2017). Depression and inflammation: unraveling a clear but complex and multifaceted link. Neuropsychiatry. 07. 10.4172 / Neuropsychiatry.1000236.
      • Raison, Charles and Capuron, Lucile and Miller, Andrew. (2006). Reason CL, Capuron L, Miller AH. Cytokines sing the blues: inflammation and the pathogenesis of depression. Immunol Trends 27: 24-31. Trends in immunology. 27. 24-31. 10.1016 /
      • Dowlati Y, Herrmann N, Swardfager W et al. A meta-analysis of cytokines in major depression. Biol. Psychiatry 67 (5), 446-457 (2010).
      • Martinez JM, Garakani A, Yehuda R et al. (2012) Pro-inflammatory and “resistance” proteins in the CSF of patients with major depression. Depress. Anxiety 29 (1), 32 – 38.
      • Krishnadas R, Cavanagh J. (2012) Depression: an inflammatory disease? J. Neurol. Neurosurgery. Psychiatry 83 (5), 495-502.
      • Kiecolt-Glaser JK, Derry HM, Fagundes CP (2015). Inflammation: Depression promotes flames and heat parts. Estic J. Psych 172 (11), 1075-1091.

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