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Paper published in Lancet Psychiatry may help with the accurate detection of this form of autoimmune encephalitis

Encephalitis

NMDAR-antibody encephalitis is an autoantibody-mediated disease (a disease caused by a person’s own immune system reacting to proteins in the brain).

Patients typically present with psychiatric features, often before any neurological features appear. This means that sometimes patients can enter and continue down psychiatric pathways and in mental health settings. These settings are not usually optimised for the care of patients with encephalitis. For example, access to lumbar puncture is rare – an essential part of the diagnosis of any encephalitis. This can understandably delay the diagnosis of NMDAR-antibody encephalitis, leading to lags in the initiation of appropriate immune treatments. 

A new study by Al-Diwani et al in Lancet Psychiatry looked at the available world literature of individually-described patients with NMDAR-antibody encephalitis. The authors were able to identify 464 patients who based upon their symptoms and NMDAR-antibody in their spinal fluid were judged to definitely have this condition. They then extracted the changes in their mental state and modelled the extent to which they resembled primary mental illnesses such as schizophrenia, depression and mania.   

The study found that patients with NMDAR-antibody encephalitis presented with a complex co-existing mix of mental state changes, most commonly a combination of mood, psychosis, behavioural, sleep and catatonia which are best described by mixing traditional psychiatric diagnoses. This pattern became more stable when focusing on the cases that had the most detailed descriptions, emphasising the need for professionals to be detailed and clear when describing and reporting mental states.

These observations should encourage the accurate detection of this form of autoimmune encephalitis and differentiate it from other serious mental-health illnesses. In addition, also by contrast to primary psychiatric illnesses, NMDAR-antibody encephalitis often occurs over days and patients typically have seizures and a distinctive movement disorder. Taken together, this set of observations aims to identify this group of immune therapy-sensitive patients from within unselected psychiatric presentations.

The findings of this paper mean:

  • Psychiatrists and other mental health professionals assessing patients with new severe mental health features should have a more nuanced understanding of NMDAR-antibody encephalitis. This may help them to be more confident in who they should consider has NMDAR-antibody encephalitis and who is more likely to not have this illness.
  • This can help guide spinal fluid and blood testing to reduce the need for over-invasive and unnecessary tests and potentially inappropriate immune treatments.
  • It may set the scene for future work to develop clinical triage approaches to speed up the diagnosis of NMDAR-antibody encephalitis.
  • Urgent conversations must be had between neurological and psychiatric communities in order to identify the best way to select and test these NMDAR-antibody encephalitis patients.

Link to BBC News item about this research