Researchers studied over 22,000 Americans to understand if body inflammation is connected to depression and anxiety. They measured a simple blood test marker called CLR (a ratio of two types of immune cells) and found that people with higher CLR levels were more likely to have depression or anxiety. This suggests that inflammation in the body might play a role in mental health problems. The findings could help doctors identify people at risk and develop new ways to treat depression and anxiety by reducing inflammation.

The Quick Take

  • What they studied: Whether a simple blood test that measures body inflammation (called CLR) is connected to depression and anxiety in American adults
  • Who participated: Over 22,000 people from across the United States who participated in a national health survey between 2015 and 2023. The group included people of different ages, races, and health backgrounds
  • Key finding: People with higher inflammation markers were about 49% more likely to have depression and 13% more likely to have anxiety, even after accounting for other health factors
  • What it means for you: A simple blood test might help doctors identify who is at higher risk for depression or anxiety. However, this doesn’t mean inflammation causes these conditions—it just shows they’re connected. More research is needed before doctors use this test routinely

The Research Details

Researchers used information from a large national health survey that tracks the health of thousands of Americans. They looked at blood test results and health questionnaires from people between 2015 and 2023. They measured something called CLR, which is calculated by comparing two types of cells found in blood: C-reactive protein (a sign of inflammation) and lymphocytes (white blood cells that fight infection). They then used statistical methods to see if people with higher CLR levels were more likely to report depression or anxiety symptoms.

The researchers were careful to account for other factors that might affect the results, like age, race, smoking status, and whether people had other health conditions like high blood pressure or diabetes. This helps them understand if the inflammation connection is real or if other factors are responsible.

This approach is important because it uses real-world data from a diverse group of Americans rather than just studying one type of person. The large number of participants (over 22,000) makes the results more reliable. By looking at actual blood tests and health records, researchers can spot patterns that might not be obvious in smaller studies

This study has several strengths: it included a very large and diverse group of people, used actual blood test measurements rather than estimates, and carefully controlled for other health factors. However, because it’s a snapshot in time rather than following people over years, we can’t be certain that inflammation causes depression—only that they’re connected. The study also relied on people’s own reports of anxiety, which might not be as accurate as a doctor’s diagnosis

What the Results Show

The main finding was that people with higher CLR levels (more inflammation) had significantly higher chances of having depression. Specifically, for every increase in CLR, the odds of depression went up by 49%. For anxiety, the increase was smaller but still meaningful at 13%. These connections remained strong even after researchers accounted for age, weight, smoking, and other health conditions.

Interestingly, the relationship wasn’t perfectly straight—there were specific turning points where the risk jumped more sharply. For depression, this happened when CLR reached 0.96, and for anxiety at 0.88. Below these points, the connection was weaker; above them, the risk increased more dramatically.

When researchers looked at different groups of people, they found that younger adults showed a stronger connection between inflammation and depression than older adults. People without high blood pressure also showed stronger connections than those with high blood pressure.

The study found that the inflammation-mental health connection varied depending on age and other health conditions. Younger people appeared more sensitive to the effects of inflammation on depression. This suggests that age might be an important factor in how inflammation affects mental health. The fact that people with high blood pressure showed weaker connections is interesting and might suggest that other factors become more important when multiple health problems are present

Previous research has suggested that inflammation plays a role in depression and anxiety, but most studies focused on one specific inflammation marker. This study is notable because it looks at CLR, which combines two different measurements and might give a more complete picture of inflammation. The findings support the growing scientific understanding that mental health and physical inflammation are connected, though researchers still don’t fully understand how or why

This study has important limitations to consider. First, it’s a snapshot—researchers looked at people at one point in time rather than following them over years to see if inflammation actually causes depression. Second, anxiety was measured by asking people if they had anxiety symptoms, which is less precise than a doctor’s diagnosis. Third, the study can’t prove that inflammation causes depression or anxiety, only that they’re associated. Finally, while the study included diverse Americans, the results might not apply to people in other countries with different genetics or lifestyles

The Bottom Line

Based on this research, there’s moderate evidence that reducing inflammation might help with depression and anxiety symptoms. This could include eating anti-inflammatory foods (like fish, vegetables, and berries), exercising regularly, managing stress, and getting enough sleep. However, these are general health recommendations—this study doesn’t prove that treating inflammation will cure depression or anxiety. Anyone with depression or anxiety should work with a healthcare provider on a complete treatment plan

This research is most relevant for people struggling with depression or anxiety who want to understand all possible contributing factors. It may also interest healthcare providers looking for new ways to identify at-risk patients. However, this study doesn’t change current treatment recommendations—it’s exploratory research that suggests a direction for future studies. People should not stop taking mental health medications based on this research

If someone decided to reduce inflammation through lifestyle changes, they might notice mood improvements within 4-8 weeks, though this varies greatly between individuals. Mental health improvements typically take time, and combining these approaches with professional treatment (therapy or medication) is most effective

Want to Apply This Research?

  • Track weekly mood scores (1-10 scale) alongside anti-inflammatory behaviors like servings of vegetables, exercise minutes, and sleep hours. Look for patterns over 4-8 weeks to see if mood improves when inflammation-reducing activities increase
  • Users could set daily goals for one anti-inflammatory behavior: 30 minutes of movement, one serving of fatty fish or nuts, or 7+ hours of sleep. The app could send reminders and track consistency, helping users see the connection between these habits and mood improvements
  • Create a monthly dashboard showing mood trends alongside inflammation-reducing behaviors. Users can note any changes in depression or anxiety symptoms and correlate them with their lifestyle choices, creating personalized insights about what helps them most

This research suggests an association between inflammation and depression/anxiety but does not prove that inflammation causes these conditions. This study should not be used to diagnose, treat, or replace professional mental health care. If you’re experiencing depression or anxiety, please consult with a qualified healthcare provider or mental health professional. Do not stop or change any medications without medical supervision. While lifestyle changes like exercise and diet may support mental health, they are not substitutes for evidence-based treatments like therapy or medication when clinically indicated.