Link between Depression and Inflammation

The Link between Depression and Inflammation by Dr. Luminita Alex

The Link between Depression and Inflammation by Dr. Luminita Alex 3

Research shows that inflammation and the immune system play a huge role in depression. A growing number of scientists are suggesting that depression is a result of inflammation caused by the immune system.  When inflammation is triggered by infection, injury, or bacterial/viral invasion, the reaction produces chemical inflammatory messengers called cytokines.   

How does this translate to depression? Think about how you feel when you have the bad flu and how exhausted and irritable you feel.  That feeling of being exhausted and too achy to get up off the couch is known among psychologists as “sickness behavior. ” These behaviors are evolutionary mechanisms to make you rest so that you have available energy to go towards fighting infection and also prevent spreading infection.  

Interesting that sickness behaviors look a lot like depression.  They are in fact linked and research is showing the common denominator in the link is inflammation.  

Cytokines: inflammation chemicals in depression

 In depression, it has been shown that cytokines and inflammation greatly increase.  Healthy individuals that are vaccinated for typhoid can temporarily be put into a depressed and anxious state due to the spike of inflammatory chemicals.  Cancer patients that are given the drug interferon-alpha, which helps fight cancer by increasing inflammatory response, often go into a deep depression as a side-effect.  Inflammatory cytokines appear to set off inflammation in the body, and switch the brain into “sickness mode.”

If one is experiencing depression, looking for signs of inflammation and the many possible causes of inflammation is important for assessment and treatment. 

There are many causes of inflammation and here are a few:

  • Infection (especially dental)
  • high trans-fat diet
  • high saturated fat diet
  • high sugar diet
  • Autoimmune disease
  • Obesity (abdominal fat cells produce inflammatory cytokines)
  • Stress
  • Too much cortisol or too little
  •  Hormone dysfunction
  • Toxic exposure such as pesticides, xenoestrogens, solvents.

Food Allergies and your mood

Food allergies and intolerances can profoundly affect one’s mood.  I have had many patients whose neurological symptoms such as depression, anxiety, migraines, or ADHD lifted once we identify key food intolerances/allergies.   The most common one is gluten, but other foods can affect mood also including sugar, soy, dairy, corn, and eggs.  However, I have seen immune responses to foods one would never think of having an intolerance to, such as lemon, salmon, or chia seeds, among many others.  

Infections and the brain

The pediatric condition called “PANDAs”, (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections), causes extreme behavior and mood changes in children such as inability to focus, compulsive behavior, violent behavior.  The condition is brought on by a simple streptococcal infection such as strep throat.   PANDAs show us the effect of infection and inflammation on brain functioning and mood dysregulation. 

Autoimmune conditions

Autoimmune conditions that cause systemic inflammation produce brain symptoms along with body symptoms.  A whopping 70% of Lupus sufferers also develop neurological symptoms such as depression, anxiety, and dementia.  

Anti-inflammatory treatment possibilities for depression

There is a clear link between depression and inflammation that can and should be explored by a functional medicine doctor, especially in depression cases that are not directly related to life events, such as the death of a loved one, divorce, or loss of a job.   Looking for possible causes of inflammation is key to getting relief from depressive symptoms.   

Some things to do that may help with decreasing inflammation is adopting an anti-inflammatory diet, anti-inflammatory supplements such as fish oil and/or turmeric, and re-establishing healthy digestive flora, clearing out gastrointestinal infections, and/or repairing a leaky gut.  

Treatment of depression is multi-factorial and may require extensive investigation and treatment for relief from symptoms.  See a qualified functional medicine doctor or a licensed Naturopathic Physician before starting any treatment plan.  For more information,  click here.  


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1)Miller et al. Inflammation and its discontents: the role of cytokines in the pathophysiology of major depression. Bio Psychiatry, 2009 May 1; 65(9): 732-41. 2)Brietzke E, Stertz L, et al. Comparison of cytokine levels in depressed, manic, and euthymic patients with bipolar disorder. Journal of Affective Disorders, 2009 Aug; 116(3): 214-217.3)Harrison NA, Brydon L, Walker C, et al. Neural origins of human sickness in interoceptive responses to inflammation. Biological Psychiatry, 2009 Sept 1; 66(5): 415-422. 4)Leung, Wendy. Treating the brain and the immune system in tandem. The Globe and Mail. Jan. 18, 2015. 5)Williams, Caroline. Is depression a kind of allergic reaction? The Guardian. Jan. 4, 2015.

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