The link between depression and inflammation
Several studies have described the link between depression and inflammation, since there are not a few patients diagnosed with an inflammatory disease who manifest depressive symptoms.
It is not that the idea that having inflammation will always lead to depression is defended, but it has been Given that both conditions present a high comorbidity, which suggests that they have a biological link in common
Next we will talk about the theory that tries to explain this phenomenon, in addition to delving into the biological causes behind this process.
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The link between depression and inflammation
It has been seen that patients diagnosed with major depression are more prone to presenting inflammatory processes. In turn, people who suffer from chronic diseases, in which a high immune response is produced, are more likely to be diagnosed with a mood disorder.
Among the diseases in which inflammatory processes occur in which it has been possible to see the most relationship with depression we have, to name just a few, diabetes, rheumatoid arthritis, asthma, multiple sclerosis, cardiovascular problems, chronic pain and psoriasis.
Next we will see the main theory that has tried to establish and explain the relationship between both health problems.
brain on fire theory
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 who are diagnosed with major depression have higher levels of a factor that is involved in inflammatory processes, cytokines.
It seems that cytokines can alter the brain at a functional and structural level, which would induce changes in both mood and cognitive abilities.
It has been suggested that inflammatory processes in Western societies would be related to a unhealthy lifestyle, especially relating it to two factors: diet and pollution environmental.
Others, on the other hand, maintain that the cause could be internal, caused by our way of reacting to environmental stressors, along with a style of thinking that induces worry in a maladaptive way, manifesting itself in physiological symptoms such as inflammation.
That is, we are so stressed and depressed that our body reacts physiologically, and that causes immunological diseases to occur.
Stressful situations cause the body to release the stress hormone cortisol.. In turn, this hormone causes the levels of cytokines to increase in the blood, and substances that are related to wear and tear at the cellular level, such as nitric oxide.
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Mechanisms that would be behind this link
The organism, being healthy, reacts to external pathogens through immunological processes. In this way, it activates the cells in charge of defending the human body, preventing pathogens, be they viruses, bacteria or parasites, from running wild and reaching their goal: making us sick.
However, the immunological process already implies some wear and tear and temporary discomfort while the organism tries to face the external threat.
The inflammatory process is that response against threat, and involves some temporary discomfort, such as occurs when one has a fever or inflammation in a part of his body.
The hypothesis behind the idea of the brain on fire is that social pressures, insecurities and any psychological problem can induce this same inflammatory response, as if a virus were they will try
The problem of social pressures is that they are difficult to solve or decrease and, if the person copes with them in a maladaptive way, they subject their brain to constant stress. This causes psychopathology and organic problems to manifest.
Depression and inflammatory biomarkers
Cytokines, or cytokines, are proteins that are released during the inflammatory process, and serve to activate the immune system, stimulating it to face external threats.
As we have already seen, one of the inflammatory biomarkers, cytokines, is shown in higher amounts in people who are experiencing depression, which could be the biological link between inflammatory processes and health mental.
Cytokines and cognitive problems
Patients who have depression have been shown to have, on average, greater problems at the cognitive level compared to people without the diagnosis.
The problems become especially important in areas such as attention, executive functions, memory, in addition to showing other cognitive deficits.
It has been seen that these problems correlate positively with having higher levels of cytokines and also with the presence of other factors involved in the inflammatory process.
It seems that cytokines and other immunological factors could play a central role in synaptic plasticity and other cellular mechanisms involved in cognition.
This relationship between inflammation at the neurological level and cognitive dysfunctions has its evidence, especially if a disease such as Parkinson's, Alzheimer's or cognitive impairment is taken into account mild.
It is quite well known how beta-amyloid plaques, which are present in various dementias, affect cognitive function and inflammatory processes are also involved, along with cytokines.
Thus, neuroinflammatory processes seem to lead to changes at the cognitive and behavioral levels through various mechanisms, including changes in gene expression and neuronal functioning.
Depression in patients with inflammatory diseases
The inflammation acquires a very important role in several metabolic, neurological and behavioral conditions. Not surprisingly, it has been associated with depression. Next we will see several medical problems in which this immunological process occurs and that can be related to depression.-
Depression in diabetic people
It has been known for some time that there is a relationship between depression and diabetes.
There is a high prevalence of people with insulin problems who manifest symptoms of depression; but, since both depression and diabetes are two very common conditions, some comorbidity is to be expected.
However, epidemiological studies have seen that the two diseases co-occur too frequently, which has suggested a relationship between sugar levels and manifesting depressive symptoms.
It should be said that, although well-treated diabetes is not fatal, it is a chronic condition, which would cause the newly diagnosed person to experience depression for a while.
What has been seen is that the having high blood glucose levels is statistically associated with having a low mood.
Also, the lifestyle of many depressed people and diabetic people coincide. Frequently, in both diagnoses, the profile of the person is that of someone who eats food rich in sugars and fats, as well as being sedentary.
Depression, rheumatoid arthritis and multiple sclerosis
The Depression seems to occur 5 to 10 times more often in people with a serious medical problem, as are diseases of the arthritis or sclerosis type, where the person progressively weakens.
It has been seen that about half of the people who suffer from multiple sclerosis, either due to a biological mechanism inflammation-depression or because they are aware that their disease is chronic and neurodegenerative, they are diagnosed with major depression.
In other diseases, also of an inflammatory type, such as rheumatoid arthritis, psoriasis and gastrointestinal diseases such as Crohn's, the ratios range between 13 and 17% of cases with depression.
conclusions
Based on the literature consulted, it appears that the link between depression and inflammation is strong, being seen in multiple medical conditions in which there is involvement at the immunological, metabolic, behavioral and cognitive level.
Depression occurs in a higher percentage in people who have been diagnosed with a disease that affects endocrine level, such as diabetes, inflammatory diseases such as arthritis, sclerosis and problems gastrointestinal.
In any case, despite the relationship between both problems, it is possible to understand the idea that one will not necessarily generate the other. The reason why a person with a chronic illness has been diagnosed with depression may be because, after receive a diagnosis of your medical problem, have become depressed because of it, not as a symptom of the illness medical.
Bibliographic references:
- Amodeo, Giovanni & Trusso, Maria & Fagiolini, Andrea. (2017). Depression and Inflammation: Disentangling a Clear Yet Complex and Multifaceted Link. Neuropsychiatry. 07. 10.4172/Neuropsychiatry.1000236.
- Raison, Charles & Capuron, Lucile & Miller, Andrew. (2006). Raison CL, Capuron L, Miller AH. Cytokines sing the blues: Inflammation and the pathogenesis of depression. Trends Immunol 27: 24-31. Trends in immunology. 27. 24-31. 10.1016/j.it.2005.11.006.
- 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) Proinflammatory and “resiliency” proteins in the CSF of patients with major depression. Depress. Anxiety 29(1), 32-38.
- Krishnadas R, Cavanagh J .(2012) Depression: an inflammatory illness? J. Neurol. Neurosurg. Psychiatry 83(5), 495-502.
- Kiecolt-Glaser JK, Derry HM, Fagundes CP (2015). Inflammation: Depression Fans the Flames and Feasts on the Heat. Am. J. Psych 172(11), 1075-1091.
