NMDAR antibody encephalitis and novel diagnostic markers

Tuesday 07 August 2018

Mater’s Neurosciences Unit and Betty McGrath Fellow Dr Andrew Swayne have been studying abnormal immunological markers in patients who have experienced first episode psychosis to determine if more reliable diagnostic tools are available.

Autoimmune encephalitis is an inflammation of the brain caused by the body’s immune system attacking healthy brain cells. Recent research has shown that abnormal immune responses may be responsible for a small but significant subgroup of patients with acute psychosis.

Currently testing for autoimmune encephalitis is challenging as there are few reliable diagnostic tools.  Diagnosis of autoimmune encephalitis is made by testing for NMDAR (N–methyl-D-aspartate receptors) antibodies in plasma and cerebrospinal fluid (CSF). Testing cannot be conducted through electroencephalography (EEG) and magnetic resonance imaging (MRI), as the changes are often non-specific or absent.

The Royal Australian and New Zealand College of Psychiatrists (RANZCP) recommends testing patients the first time they experience psychotic symptoms, as early diagnosis and treatment result in the most favourable prognosis for patients.

However there are extensive costs associated with universally screening patients and without reliable confirmatory tests there is a risk this might lead to a substantial number of false positives.

The team’s research has shown there are patients currently in mental health services who have anti-NMDAR encephalitis but are currently receiving standard care for psychosis. More research is needed to determine whether immunotherapy, either in addition to antipsychotic treatment or as an alternative, improves the long-term outcome in those patients.

The diagnosis of autoimmune encephalitis is primarily based on the presence of these described antibodies in the patient, and as yet there are few other reliable diagnostic tools. The development of confirmatory testing, (such as advanced imaging techniques) to establish the presence of inflammation in the central nervous system would help clinicians provide the most appropriate treatment to the patient based on their specific condition.

Dr Swayne has recently received a Junior Doctor Research Fellowship from Queensland Health for this work. The purpose of the fellowship is to give doctors the research skills they need to build their research capacity to help improve patient outcomes.

This research was recently published in the Australian and New Zeraland Journal of Psychiatry - http://journals.sagepub.com/doi/full/10.1177/0004867418782421