Brain Injury and Autoimmune Disease in Veterans

What This Article Covers

Many veterans living with traumatic brain injury (TBI) and post-traumatic stress disorder (PTSD) develop symptoms months or years after the original injury that no one connects back to it. Joint pain. Persistent fatigue. Thyroid changes. Digestive problems. Skin changes. Hormone disruption. Eventually a clinician runs the right labs and uses a word the veteran did not expect: autoimmune.

A growing body of peer-reviewed research shows that TBI, especially when combined with PTSD, significantly raises the risk that the immune system will begin attacking the body's own tissues. This article reviews what the largest studies have found, the specific autoimmune conditions involved, the often-missed role of pituitary damage, and the labs worth requesting from a healthcare provider.

How Brain Injury Triggers an Immune Response

The brain is normally protected by the blood-brain barrier, a structure that keeps brain tissue isolated from the rest of the immune system. The body has never been formally introduced to most of what is inside the skull, and that isolation is intentional.

When a head injury occurs, that barrier breaks. Damaged brain cells release brain-specific proteins into the bloodstream, including glial proteins such as S100B and glial fibrillary acidic protein, myelin basic protein from the insulation around nerve fibers, and fragments of neuroreceptors. The immune system encounters these proteins for the first time and responds the way it responds to anything unfamiliar. It produces antibodies against them.

A review published in Current Physical Medicine and Rehabilitation Reports documents that a subset of TBI patients develops circulating autoantibodies targeting brain proteins after injury, including antibodies against glial proteins, neuroreceptors, and myelin. The immune system begins treating the brain as foreign tissue.

In most people, this response is temporary. The barrier closes, and the antibodies fade. In a smaller group of patients, particularly those with combined TBI and PTSD, the immune response does not shut off. It becomes chronic. Once the immune system has been primed to attack one type of tissue, it can extend that attack to other tissues throughout the body.

Related reading:

• How Blast Exposure Affects the Brain
• Breacher's Syndrome: Blast Exposure and Brain Injury

What the Largest Studies Have Found

The largest study on this question was published in 2015 in Biological Psychiatry. Researchers at the San Francisco VA Medical Center analyzed records from 666,269 Iraq and Afghanistan veterans enrolled in the VA healthcare system.

Veterans diagnosed with PTSD had twice the risk of being diagnosed with an autoimmune disorder compared to veterans with no psychiatric diagnoses. Compared to veterans with psychiatric conditions other than PTSD, the PTSD group still had a 51 percent higher risk. The increased risk applied equally to men and women. Military sexual trauma exposure was independently associated with elevated risk in both groups.

The autoimmune conditions specifically over-represented in this cohort were:

• Rheumatoid arthritis
• Systemic lupus erythematosus (lupus)
• Multiple sclerosis
• Inflammatory bowel disease
• Autoimmune thyroiditis

A separate 2025 study in Frontiers in Lupus examined veterans with TBI specifically. Among those with TBI alone, 4.3 percent had an autoimmune disease. Among those with both TBI and PTSD, that number rose to 12.4 percent. Rheumatoid arthritis was over-represented by roughly four-fold in the TBI-plus-PTSD group compared to general population prevalence.

A 2020 analysis of active-duty service members from the Millennium Cohort Study reached the same conclusion in a younger population. PTSD raised autoimmune disease risk, and the pattern held in active-duty personnel, not just in veterans years out from service.

The Pituitary Gland and Hormone Disruption

One of the most under-recognized consequences of brain injury is damage to the pituitary gland, a small hormone-producing structure at the base of the brain. The pituitary controls thyroid function, cortisol production, growth hormone, sex hormones, and the body's stress response.

When the pituitary is damaged, the effects can include depression, exhaustion, weight changes, low libido, brain fog, and irritability. Many veterans are told these symptoms are psychiatric when the underlying cause is endocrine.

A meta-analysis cited in Hypothalamic-Pituitary Autoimmunity and Traumatic Brain Injury found that across more than 1,000 adult TBI patients followed for three months to seven years post-injury, the pooled prevalence of post-traumatic hypopituitarism was 27.5 percent. Roughly one in four people with a brain injury develops some degree of pituitary dysfunction.

The autoimmune component is significant. A study in the European Journal of Endocrinology tested patients three years after TBI and detected anti-pituitary antibodies in 44.8 percent of them, compared to zero percent in matched healthy controls. Elevated antibody levels were associated with persistent pituitary dysfunction, particularly affecting growth hormone and the hormones that regulate testosterone in men.

The immune system, once activated by the brain injury, can continue attacking the pituitary gland for years after the initial trauma, slowly degrading hormonal function. Many veterans live with treatable hormone deficiencies that have been misdiagnosed as PTSD, depression, or normal aging.

Symptoms that may overlap with pituitary dysfunction:

• Apathy and Loss of Motivation After Military Brain Injury
• Cognitive Fatigue After Military Brain Injury
• Sleep Problems After Military Brain Injury

Why TBI Plus PTSD Carries Higher Risk

Research consistently shows that the combination of TBI and PTSD is associated with worse outcomes than either condition alone, not only for psychiatric measures but for physical health as well.

PTSD produces measurable changes in the immune and endocrine systems. Research summarized in PMC documents that PTSD is associated with elevated inflammatory cytokines, hyperactive immune responses, and disrupted cortisol regulation. When these immune effects are layered on top of the immune disruption caused by a brain injury, two separate biological processes push the system in the same direction.

Up to two-thirds of combat veterans with PTSD also have a history of TBI. These are largely the same people, not separate populations. Caregivers and clinicians have observed for years that this combined population presents with physical symptoms that exceed what psychiatric diagnoses alone can explain. The research now provides a mechanism for those observations.

Related reading on the TBI and PTSD overlap:

• PTSD vs TBI in Veterans: Why Symptoms Overlap
• Early Signs of Brain Injury in Veterans
• Personality Changes After Military Brain Injury

The Dementia Connection

Chronic inflammation from autoimmune disease has been linked to accelerated neurodegeneration. A nationwide cohort study published in PMC tracked 34,660 middle-aged patients with autoimmune rheumatic diseases against 138,640 matched controls. The autoimmune group had an 18 percent higher risk of developing dementia. Sjögren syndrome carried the highest risk (46 percent increase), followed by rheumatoid arthritis.

This produces a connected sequence of risks for veterans with TBI and PTSD. Brain injury triggers immune activation. Immune activation drives autoimmune disease. Autoimmune disease accelerates dementia risk. For a population already at elevated risk for cognitive decline and conditions such as chronic traumatic encephalopathy, the addition of autoimmune disease is part of the larger picture, not a separate problem.

Related reading on long-term neurodegenerative risk:

• CTE Symptoms in Veterans
• CTE in Veterans: Why It Presents Differently

Symptoms Worth Discussing with a Clinician

Autoimmune diseases are difficult to diagnose because the symptoms overlap with many other conditions, including conditions associated with TBI and PTSD themselves. Certain patterns are worth raising with a healthcare provider:

• Joint pain and stiffness that lasts longer than 30 minutes in the morning, or that affects the same joints on both sides of the body.
• Persistent fatigue that does not improve with sleep and feels qualitatively different from PTSD-related exhaustion.
• Unexplained weight changes, hair loss, cold intolerance, or heat intolerance (potential thyroid involvement).
• Dry eyes or dry mouth that persist (potential Sjögren syndrome).
• Skin rashes, especially butterfly-shaped on the face, or rashes that flare in sunlight (potential lupus).
• Chronic digestive issues including persistent diarrhea, bloody stools, or severe abdominal cramping (potential inflammatory bowel disease).
• New numbness, tingling, or vision problems, especially in younger veterans (potential multiple sclerosis).
• Loss of libido, erectile dysfunction, or menstrual changes that have been attributed to stress or depression (potential pituitary involvement).

Sensory and cognitive changes may share underlying mechanisms with the immune and inflammatory processes described above:

• Sensory Overload After TBI in Veterans

Labs Worth Requesting

If multiple symptoms above are present, or if there is a clinical suspicion that something more than PTSD is contributing to the picture, specific labs can help clarify what is happening. These are standard tests, not specialty assays.

• ANA (antinuclear antibody). Screening test for lupus and other autoimmune conditions.
• Rheumatoid factor (RF) and anti-CCP antibodies. For rheumatoid arthritis.
• TSH, free T4, and TPO antibodies. For thyroid function and autoimmune thyroid disease.
• CRP and ESR. General inflammation markers.
• Morning cortisol and ACTH. For adrenal and pituitary function.
• IGF-1. For growth hormone status.
• Testosterone (total and free) for men, FSH and LH for both. For the pituitary-gonadal axis.
• Prolactin. Often elevated in pituitary dysfunction.

If a clinician declines to order these tests on the grounds that PTSD already explains the symptoms, the published research provides a clear rationale for further workup. Veterans with PTSD and TBI are a documented higher-risk population for autoimmune and endocrine disease. The labs above are inexpensive and widely available.

VA Service Connection

Veterans already service-connected for PTSD who are later diagnosed with an autoimmune condition or post-traumatic hypopituitarism may have grounds for a secondary service connection claim. The published research linking PTSD to these conditions, particularly the O'Donovan 2015 study, has been cited by veterans' disability attorneys in support of such claims. This article does not constitute legal advice. Veterans considering a claim should work with a Veterans Service Officer (VSO) or accredited claims agent who can evaluate the specifics of their case.

Additional veteran resources:

• Military Brain Injury Support Resources
• How to Help a Veteran with PTSD
• GHOST OPS: Veterans TBI/PTSD Community

Summary

Traumatic brain injury and PTSD affect more than cognition and mood. Both can disrupt the immune system in ways that increase the risk of autoimmune disease and pituitary dysfunction, sometimes years after the original injury. For veterans whose physical symptoms have been attributed solely to psychiatric diagnoses, the published research supports a more thorough workup, including rheumatologic and endocrine evaluation. Recognizing this connection earlier allows for treatable conditions to be addressed before they progress, and may inform decisions about VA service connection and long-term care.

Sources:

• O'Donovan A, Cohen BE, Seal KH, et al. Elevated risk for autoimmune disorders in Iraq and Afghanistan veterans with posttraumatic stress disorder. Biological Psychiatry. 2015;77(4):365-374.
• Rheumatic autoimmune disease in relation to post-traumatic stress disease and traumatic brain injury. Frontiers in Lupus. 2025.
• Tanriverdi F, De Bellis A, Bizzarro A, et al. Antipituitary antibodies after traumatic brain injury: is head trauma-induced pituitary dysfunction associated with autoimmunity? European Journal of Endocrinology. 2008;159(1):7-13.
• Tanriverdi F, Kelestimur F. Hypothalamic-pituitary autoimmunity and traumatic brain injury. Journal of Clinical Medicine. 2015.
• Bookwalter DB, Roenfeldt KA, LeardMann CA, et al. Posttraumatic stress disorder and risk of selected autoimmune diseases among US military personnel. BMC Psychiatry. 2020.
• Lin TM, Chen WS, Sheu JJ, et al. Autoimmune rheumatic diseases increase dementia risk in middle-aged patients: A nationwide cohort study. PLOS ONE. 2018.
• Co-Morbidity of PTSD and Immune System Dysfunction: Opportunities for Treatment. PMC. 2016.

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This article is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider regarding diagnosis and treatment.