Chronic inflammation may trigger or worsen depression, especially in those with autoimmune or chronic conditions.

Depression is a widespread mental health condition with many possible causes. Inflammation, particularly in cases with autoimmune or chronic health conditions, can be one contributing factor.

It’s important to recognize this possibility because it can impact how your depression should be treated.

There’s evidence to suggest that inflammation can contribute to the development of depression in many people, particularly among individuals with preexisting inflammatory conditions or chronic illnesses.

For instance, research suggests that the link between inflammation and depression is commonly seen in conditions like autoimmune diseases (e.g., multiple sclerosis) and infections (e.g., sepsis) where the immune system plays a significant role.

What mood disorders are linked to inflammation?

This may not apply to everyone with a mood disorder, but inflammation has been associated with the following:

  • Atypical depression (AD): Research suggests that Inflammation appears to be more severe in people with major depressive disorder with atypical features compared to non-AD and healthy individuals.
  • Major depressive disorder (MDD): In MDD, there’s evidence of hormonal changes, increased pro-inflammatory cytokines in the bloodstream, and markers of oxidative stress.
  • Bipolar disorder: Some research has found increased levels of inflammatory markers in individuals with bipolar disorder. Evidence also suggests there may be immunological alterations (dysfunction of the immune system) during manic episodes.
  • Seasonal affective disorder (SAD): A 2015 study found that people with SAD showed increased inflammatory responses compared to healthy subjects. Light therapy improved both immune function and depressive symptoms in these individuals.
  • Postpartum depression: Some evidence suggests that women with postpartum depression have elevated levels of certain inflammatory biomarkers.

When your immune system is activated, it affects not only the body but also the central nervous system, which includes the brain. Chronic inflammation is linked to changes in the brain’s chemistry and structure, which can increase the risk of depression.

Inflammation can impact mental health in several ways:

  • Neurotransmitter imbalance: Research suggests that inflammation may disrupt brain chemicals (neurotransmitters) like serotonin and dopamine, leading to mood imbalances.
  • Hormonal disruption: Inflammation can affect stress and sex hormone levels (e.g., cortisol, estrogen), impacting mood and cognition.
  • Neuroinflammation: Evidence suggests that inflammation within the brain itself can cause cognitive and mood problems.
  • Reduced neuroplasticity: Chronic inflammation may hinder the brain’s ability to adapt and learn.
  • Oxidative stress: Inflammation may increase oxidative stress, damaging brain cells.

Does everyone with depression have inflammation?

There’s no evidence to suggest that all individuals with depression have inflammation.

The connection between depression and inflammation is complex and varies among people, with a more significant link observed in some cases, particularly those with specific medical conditions or subtypes of depression.

In many adults, depression and inflammation appear to be separate issues. One study found that clinical depression in older individuals isn’t typically linked to increased inflammation unless they have preexisting inflammatory conditions like arthritis.

Determining if your depression is caused by inflammation typically involves specialized medical tests and assessments. This may involve blood tests to measure inflammatory markers or discussions with your doctor about your medical history and symptoms.

However, here are some signs that suggest inflammation may be contributing to your depression:

  • You have other inflammatory conditions (e.g., autoimmune disorders, chronic infections, or inflammatory bowel disease).
  • Your depression had a sudden onset (especially in response to an infection or injury).
  • Your depression doesn’t respond to antidepressants.
  • You have physical symptoms (e.g., fatigue, joint pain, or fever)
  • You have high stress levels (chronic stress can trigger inflammation).
  • You have a family history of both depression and inflammatory conditions.
  • You have elevated markers of inflammation, like CRP or cytokines, in specialized blood tests.

Treatment options for inflammation-related depression typically aim to target both the underlying inflammation and the depressive symptoms. Here are some common approaches:

  • Anti-inflammatory medications: Some evidence suggests that nonsteroidal anti-inflammatory drugs (NSAIDs) or anti-inflammatory agents like corticosteroids may be prescribed to reduce inflammation.
  • Healthy diet: A comprehensive review of 41 studies revealed that maintaining a consistently healthy diet, especially one in line with the traditional Mediterranean diet, or simply avoiding diets that promote inflammation, may protect against depression.
  • Psychotherapy: Cognitive-behavioral therapy (CBT) and mindfulness-based therapies may help manage depression symptoms.
  • Medications: Some evidence suggests that certain antidepressants, like selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs), can reduce inflammation in the brain, which may contribute to their effectiveness.
  • Light therapy: A 2017 study found that combining bright light therapy with antidepressants for nonseasonal depression could be effective. Participants also showed significant changes in immune-related lymphocyte counts.
  • Omega-3 fatty acids: Omega-3 supplements, found in fish oil, have anti-inflammatory properties and may help with depression symptoms.
  • Mind-body practices: Practices like yoga and meditation can help manage stress and potentially reduce inflammation.
  • Probiotics: Some research suggests that probiotics may have a positive impact on gut health and inflammation, which could indirectly affect mood.

Depression is a complex condition with various underlying causes, and inflammation may play a role in this, especially for those with autoimmune or chronic health conditions.

If you’re dealing with depression, consider reaching out to a healthcare professional to get a full assessment. Determining whether your depression is associated with inflammation or not is important, as it can significantly affect your treatment plan.