2 Neuroscience2.8 Modulators, hormones and inflammatory responses
2.8.5 Autoimmunity and psychiatric symptoms
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Written by Resident Doctor Committee · Published
New in the 2027 syllabus
The College added this topic for exams from January 2027.
How autoimmunity affects mental state
Autoimmune disease can change mental state through neuronal antibodies, inflammatory injury, damage to blood vessels or systemic illness.
Cell-surface antibodies may reduce the number of receptors available or change how they work. N-methyl-D-aspartate (NMDA) receptor antibodies can make the neuron take the receptor inside the cell (internalisation), which disturbs signalling at the synapse.
Intracellular neuronal antibodies often mark a process driven mainly by T cells. They may point to an underlying cancer.
When to suspect a neurological syndrome
Finding with the psychiatric symptoms | Why it matters |
|---|---|
Rapid progression with new memory problems | Suggests encephalitis or another organic cause |
New seizures or focal neurological signs | Needs neurological investigation |
Catatonia, abnormal involuntary movements (dyskinesia) or reduced consciousness | Can occur in NMDA receptor encephalitis |
Unstable autonomic function | May signal severe encephalitis |
Low sodium (hyponatraemia) with brief faciobrachial dystonic seizures | Suggests leucine-rich glioma-inactivated 1 (LGI1)-associated disease |
Assessment
Combine the time course, examination, magnetic resonance imaging (MRI), electroencephalography (EEG) and cerebrospinal fluid (CSF) findings, and rule out infection and other causes.
Test serum and CSF as a pair. This helps interpretation, because the more informative sample differs between antibodies.
Normal routine tests do not rule out autoimmune encephalitis. A positive antibody result on its own does not prove it.
Traps
Common psychiatric disorders may show links with inflammation without any proven autoimmune mechanism. These findings do not justify routine immunotherapy.
Systemic lupus erythematosus can cause neuropsychiatric symptoms through inflammation or damage to blood vessels. Infection, metabolic disturbance and treatment side effects remain other possible explanations.