Can SREAT Cause Only Psychiatric Symptoms Like Psychosis?

Bottom Line: While rare cases of Steroid-Responsive Encephalopathy Associated with Autoimmune Thyroiditis (SREAT)—often called Hashimoto’s encephalopathy—have been reported to present primarily with psychiatric symptoms, this is an uncommon presentation of a rare condition. Most sudden psychosis or mood changes are not caused by SREAT. However, sudden or highly unusual psychiatric changes do require a prompt medical assessment to look for underlying causes.

Emergency Warning: If you or a loved one experiences rapidly worsening confusion, inability to stay awake, severe agitation, seizures, fever with altered mental status, or any immediate risk of self-harm or harm to others, seek emergency medical care immediately.

Psychiatric-Predominant Presentations

It is possible for SREAT to present primarily with psychiatric symptoms like psychosis, severe paranoia, hallucinations, or dramatic mood shifts ^[1][2]. Because these symptoms look very similar to primary mental illnesses (like schizophrenia or severe depression), SREAT can sometimes act as a condition that mimics other illnesses ^[1][3].

However, truly isolated psychiatric symptoms in SREAT are difficult to confirm and the subject of medical debate. When they are reported, the numbers come from selected groups of patients rather than the general population:

• Case Reports: A systematic review of 251 published SREAT case reports found that 10% of these specific patients were reported to have isolated psychiatric disorders, with about a quarter of the group experiencing persecutory delusions (severe paranoia) ^[4].
• Suspected Cohorts: Another study of a highly selected group of patients suspected to have SREAT classified 29% as having a psychiatric-dominant presentation ^[5].

These figures do not mean that 10% to 29% of all psychosis is caused by SREAT; rather, they show that among people already diagnosed with this rare condition, psychiatric symptoms are a known feature.

“Invisible” Neurological Signs and Test Results

SREAT causes encephalopathy (generalized brain dysfunction). While obvious neurological signs like seizures or severe memory loss are common, a patient experiencing SREAT-induced psychosis might have a physical neurological exam that appears normal at first glance ^[6][3]. Sometimes, subtle signs of brain dysfunction are missed during a brief examination.

Furthermore, routine brain scans and tests may not definitively prove or rule out the condition:

• Normal Scans: Case reports describe patients with SREAT-induced psychosis who have unremarkable brain MRIs ^[6], and normal MRIs are reported in most diagnosed cases ^[7].
• Inconclusive Tests: Tests like an electroencephalogram (EEG) (measuring brain electrical activity) or a lumbar puncture (spinal tap) might show abnormalities, but they can also sometimes be normal ^[6][3]. Abnormal results are often general and do not point specifically to SREAT.

These tests answer different questions and are not routinely required for every person experiencing psychiatric symptoms. Instead, doctors recommend them based on specific clinical red flags.

The Importance of a Targeted Medical Workup

A sudden, severe first episode of psychosis or a dramatic, uncharacteristic mood shift deserves a prompt and careful medical assessment ^[8][9].

While a primary psychiatric diagnosis is very often correct, doctors will look for “red flags” that suggest an underlying medical condition, such as:

• Rapidly fluctuating alertness or confusion
• Unexplained fever or headaches
• Seizures, abnormal movements, or severe stiffness (catatonia)
• Worsening symptoms despite psychiatric medication
• Autonomic instability (such as severe, unexplained fluctuations in heart rate or blood pressure)

If these red flags are present, your care team may order targeted tests to look for structural, metabolic, infectious, or autoimmune causes (including other forms of autoimmune encephalitis) ^[10][11].

The Role of Thyroid Antibodies

SREAT is associated with high levels of anti-thyroid antibodies (such as anti-TPO or anti-thyroglobulin). It is important to know that these antibodies are a sign of thyroid autoimmunity, not a brain-specific test, and the exact way they relate to brain inflammation remains unproven ^[12].

Finding thyroid antibodies alone is never enough to confirm SREAT. In studies of people with primary psychiatric conditions like schizophrenia or depression, up to 15% to 17% had elevated anti-thyroid antibodies, and they are also common in healthy individuals ^[13][14]. Furthermore, a person can have normal thyroid hormone levels but still have these antibodies, meaning that thyroid function tests (which measure hormones) and thyroid antibody tests look for different things ^[4].

Because there is no single test that proves SREAT, doctors diagnose it by piecing together the clinical syndrome, test results, and by ruling out other reasonable explanations for the encephalopathy ^[12][4]. Lastly, while a positive response to corticosteroid treatment can support the diagnosis, steroids are not specific to SREAT and carry their own risks; therefore, treatment decisions must be carefully made by a specialist after a thorough evaluation.