ADHD is not only a brain condition.
Research increasingly shows that the brain, immune system, connective tissue, and nervous system talk to each other.
For many ADHD people, especially women, this helps explain why ADHD often shows up alongside physical issues like:
🔵 Allergies or asthma
🔵 Gut problems
🔵 Chronic pain or fatigue
🔵 Dizziness or fainting
🔵 Joint hypermobility
🔵 Inflammation-related conditions
This does not mean ADHD is “caused” by these problems.
It means shared body systems may be involved.
Step 1: What is chronic inflammation
Inflammation is the body’s alarm system.
🔵 Short-term inflammation helps you heal
🔵 Long-term (chronic) inflammation keeps the alarm stuck “on”
Things that can keep inflammation active include:
🔵 Allergies or asthma
🔵 Autoimmune conditions
🔵 Gut irritation or food intolerance
🔵 Poor sleep
🔵 Ongoing stress or trauma
🔵 Environmental exposures
What we know about ADHD and inflammation
Research has found:
🔵 Higher inflammatory markers in many ADHD people
🔵 More inflammation is linked to more severe ADHD symptoms
🔵 Vitamin D and iron deficiencies are common (both affect immune function)
🔵 ADHD overlaps with autoimmune and inflammatory conditions more than expected
This suggests some ADHD nervous systems live under higher baseline stress, biologically, not psychologically.
Step 2: Why hypermobility matters so much
Hypermobility means connective tissue is more elastic than average.
About half of ADHD people are hypermobile.
That matters because connective tissue is everywhere:
🔵 Joints
🔵 Blood vessels
🔵 Skin
🔵 Gut
🔵 Nervous system support structures
Some people develop:
🔵 Hypermobility Spectrum Disorder (HSD)
🔵 Hypermobile Ehlers-Danlos syndrome (hEDS)
These are body-wide conditions, not just “being flexible.”
Why this matters for ADHD
Loose connective tissue can contribute to:
🔵 Blood pooling
🔵 Gut motility problems
🔵 Pain and fatigue
🔵 Nervous system instability
Which leads us to the next piece.
Step 3: Dysautonomia (the body’s autopilot glitch)
The autonomic nervous system runs things you do not consciously control:
🔵 Heart rate
🔵 Blood pressure
🔵 Digestion
🔵 Temperature
Dysautonomia means this system does not regulate smoothly.
A common form is POTS (postural orthostatic tachycardia syndrome).
What POTS feels like
🔵 Heart racing when standing
🔵 Dizziness or lightheadedness
🔵 Brain fog
🔵 Fatigue
🔵 Feeling worse after exertion
Studies show people with POTS score higher on ADHD inattentive traits.
This does not mean ADHD causes POTS.
It means the same regulation systems may be involved.
Step 4: Mast cells and why they are being studied
Mast cells are immune cells that release chemicals like histamine.
They help with:
🔵 Allergies
🔵 Infection defense
🔵 Injury response
In mast cell activation syndrome (MCAS), mast cells react too easily.
Possible triggers include:
🔵 Foods
🔵 Heat or cold
🔵 Hormonal shifts
🔵 Stress
🔵 Infections
🔵 Environmental toxins
Why this matters for ADHD
Mast cells exist:
🔵 In the gut
🔵 Near nerves
🔵 In blood vessels
🔵 In the brain
When overactive, they can worsen:
🔵 Brain fog
🔵 Anxiety
🔵 Fatigue
🔵 GI symptoms
🔵 Dysautonomia
Some clinicians suspect MCAS may help explain why many ADHD people have “mystery” physical symptoms, but this area still needs more research.
Step 5: The gut connection
Gut problems are common in ADHD.
Possible contributors include:
🔵 Dysautonomia affecting digestion
🔵 Mast cell activation in the gut lining
🔵 Inflammation altering gut-brain signaling
When digestion is off, it can worsen:
🔵 Focus
🔵 Energy
🔵 Mood
🔵 Medication tolerance
This is bidirectional.
The brain affects the gut, and the gut affects the brain.
What this does not mean (important)
🔵 ADHD is not a disease caused by inflammation
🔵 ADHD is not “actually physical, not neurological”
🔵 Everyone with ADHD does not have these conditions
🔵 You do not need to chase diagnoses
ADHD remains a valid neurotype.
These findings simply explain why many ADHD people feel physically unwell in ways that were dismissed or misattributed.
🌿 ADHD and Inflammation: A Body–Brain Connection