⬇️ Prefer to listen instead? ⬇️
- New genetic research shows ADHD risk is directly linked to specific immune cell traits.
- ADHD might affect and be affected by how the immune system acts at the genetic level.
- Higher levels of immune markers like interleukin-6 are seen more often in people with ADHD.
- Immune-regulating cells such as monocytes and B cells could change ADHD risk, making it higher or lower.
- Finding immune biomarkers could help detect ADHD sooner and lead to treatments made just for each person.
What Is ADHD? Looking Closer Than Just Symptoms
ADHD, or attention-deficit/hyperactivity disorder, is a complicated condition that affects brain development. It’s marked by ongoing patterns of not paying attention, acting without thinking, and being too active. It’s well known in kids, but many adults also have symptoms—this is often called adult ADHD.
How We See ADHD Now
ADHD is not just a behavior problem. We now know it starts in brain development and brain chemistry. Brain scans have shown differences in how the prefrontal cortex, basal ganglia, and other brain areas are built and work. These areas control attention, planning, and stopping impulsive actions. These areas are greatly affected by brain chemicals like dopamine and norepinephrine, which are always involved in ADHD.
ADHD Through Life
While symptoms can look different as people age, ADHD often lasts past childhood. Adult ADHD can cause problems with work, dealing with stress, getting organized, and relationships. It’s surprising how many adults are not diagnosed until later in life. They often struggle for months or years with being easily distracted, not being able to track time, or having strong mood swings.
Because symptoms continue from childhood to adulthood, it suggests there’s a basic cause, possibly genetic. This cause might be closely tied to other body systems like the immune system.
The Immune System: More Than Just Fighting Illness
We usually think of the immune system as fighting infections. But recently, researchers have shown it also has a key job in brain development and keeping minds healthy. Its role in brain disorders like ADHD challenges the old idea of separating mind and body.
Swelling and Mental Health
Low-level, long-term swelling seems to be common in many mental and brain development disorders. These include depression, schizophrenia, autism, and now, ADHD. When the body is swollen, it makes signaling chemicals called cytokines, such as
- Interleukin-6 (IL-6): Usually causes swelling
- Interferon-gamma (IFN-γ): Makes the immune system more active
- Interleukin-10 (IL-10): Reduces swelling, calms down immune responses
Many people with ADHD have higher levels of IL-6 and IFN-γ and lower levels of IL-10. This suggests their immune systems are more likely to be inflamed.
New Study Design: Mendelian Randomization
Researchers at Jiangnan University were tired of the question: “Does ADHD cause immune problems, or do immune problems cause ADHD?” To solve this, they used a strong statistical method to untangle the connection: bidirectional Mendelian randomization.
What Is Mendelian Randomization?
This method uses genetic differences as natural tests to see what causes what, instead of just looking at connections. Here, they checked if ADHD-related genes affected immune traits, and if immune-related genes affected ADHD risk.
By studying data from large genome-wide association studies (GWAS), the researchers removed confusing outside factors like diet, pollution, or trauma. This gave a clearer picture of genetic cause and effect.
Using Data: Large Groups and Immune Measures
The study used a lot of genetic and immune data
- Over 225,000 people for ADHD-related genetic risk factors.
- 3,757 people from Sardinia for immune cell features.
This gave genetic data on 731 immune cell traits, including
- Total counts of white blood cells.
- Protein levels on the surface of immune cells.
- Cell কাজ and makeup, like size and how grainy they are.
These traits covered many types of immune cells, such as
- B Cells (adaptive immunity)
- T Cells (cell-mediated immunity)
- Myeloid cells like monocytes, granulocytes, and dendritic cells
Using math models, the researchers found immune markers changed by ADHD genes—and the other way around.
Immune Changes From ADHD Genetic Risk
The study found that people with a higher genetic chance of having ADHD showed certain changes in their immune system
Higher Immune Cell Traits
- Forward scatter values in myeloid dendritic cells, monocytes, and granulocytes
These values show changes in cell size or inner makeup—markers that usually mean immune cells are active or working harder.
Why Does That Matter?
These immune cells
- Are key in controlling swelling
- Talk to the central nervous system (CNS) using cytokine signals
- Are known to affect brain development before and after birth
It’s important to note that changes in immune activity can get in the way of brain growth. This can set the stage for ADHD and other brain development conditions.
Immune Traits That Change ADHD Risk
Just like ADHD can change the immune system, the opposite may also be true: genes that shape how the immune system acts may change ADHD risk.
Higher Risk From B Cells
- A surface protein called Immunoglobulin D (IgD) on B cells was linked to a higher chance of ADHD.
This suggests adaptive immune responses play a role in ADHD risk. Because B cells make antibodies and control swelling, abnormal IgD levels could cause too much immune signaling or unwanted swelling in the brain.
Lower Risk From Suppressor Traits
Five immune traits were linked to a protective effect against ADHD
- Surface and makeup features on CD14+ monocytes
- Stronger traits in basophils
- More myeloid-derived suppressor cells (MDSCs)
These immune types are known to control swelling, often stopping immune responses that are too strong. In the brain, this could mean a more balanced setting that helps with focused brain signaling and controlled behavior.
Blood-Brain Barrier: The Link Between Brain and Immune System
The blood-brain barrier (BBB) is a membrane that protects brain tissue from immune system parts. But swelling—especially from immune system activity outside the brain—can weaken this barrier.
Immune Cells and the Mind
Once weakened, swelling chemicals and immune cells can get into the brain directly. This can
- Upset brain chemical balance
- Block brain connections from forming and maturing correctly
- Start microglial activation, which are the brain’s own immune cells
These effects could add to common ADHD symptoms like acting impulsively, being easily distracted, and mood swings.
Adult ADHD: Long-Term Swelling’s Effects
While much immune impact happens during childhood brain growth, new evidence suggests the immune system is still involved in adult ADHD.
Low-Level Swelling in Adults
In adults with ADHD
- Long-term stress often adds to ongoing swelling
- Some immune cells stay too active or don’t work right
- Immune types are related to brain fog, mood swings, and attention problems
Understanding how lifelong immune activity feeds into ADHD can help explain why symptoms change or stay in adults.
Brain Development Disorders and Immune System Overlap
It’s interesting that ADHD shares immune markers with other brain conditions
- Autism Spectrum Disorder (ASD): Higher monocytes, changed T-helper cells
- Tourette Syndrome: More dendritic cell activity, swelling chemicals
This suggests a shared immunogenetic base across brain difference conditions. This fact could make diagnosis easier and help create treatments for multiple conditions.
Toward Treatments Made for Each Person
If certain immune traits add to ADHD risk or how bad it is, they could be biological markers for early checks or treatments made just for each person.
Possible Uses in Clinics
- Biomarkers for diagnosis before behavior symptoms show up
- Treatments that change the immune system, such as
- Targeting certain cytokines (like IL-6 blockers)
- Using anti-swelling drugs for other uses
- Thinking about diet and lifestyle changes to lower body swelling
While these treatments are still being tested, the connection between genes and immunology opens exciting possibilities for future research.
Limits: Where We Need More Answers
While promising, the study has limits
- The ADHD genetic type came from European groups, which may not apply to all groups.
- Not separating by sex and age makes it harder to understand for each person.
- Using less strict statistical rules means some findings might be wrong positives and need to be checked again.
Future research needs to include more diverse groups and use stricter rules to find solid ADHD–immune system links.
A Change in Thinking: ADHD as Brain-Body Connection
The most important part of this research is that it changes how we see ADHD. It’s now seen as a two-way biological talk, not just a brain problem.
A New Way to See It
- ADHD symptoms may start because of immune-caused brain changes.
- ADHD genes can, in turn, shape immune types over time.
- Outside factors like infections, diet, and stress may make both worse.
At the meeting point of genes, immunity, and brain development, ADHD looks less like just a mental problem and more like a sign of body-brain interactions.
The Path Forward: Inclusion, New Ideas, and Care
To build on these ideas, future studies should
- Include different groups by race, background, and money situation
- Consider how symptoms show up differently in men and women
- Study when symptoms start in both childhood and adult ADHD
We also need to test treatments that change the immune system as add-on therapy to stimulants or behavior treatments.
Final Thoughts: More Than Just in Your Head
The immune system’s role in ADHD changes the talk from blame and shame to biology and complexity. It also pushes for a joined-up approach—valuing immune health, genes, and brain science together.
As research moves forward, we might soon see routine blood tests, immune checks, or genetic tests used in ADHD diagnosis. This would start a new time of precise mental health care.
Suggested Reading & Next Steps
Interested in the link between immune health and mental performance? Keep following us at The Neuro Times for easy-to-understand looks into new brain science. And remember: your attention challenges aren’t a personal failing—they’re part of a complex, active talk between your DNA, your brain, and your cells.
Citations
- Du, J., Fang, L., Dong, K., & Zhou, Z. (2024). Looking at the complex link between attention deficit hyperactivity disorder and the immune system: A bidirectional Mendelian randomization analysis. Journal of Affective Disorders. https://doi.org/10.1016/j.jad.2024.10.050
