(aka AUTOIMMUNE ENCEPHALITIS)
Autoimmune encephalopathy (also sometimes called “autoimmune encephalitis”) occurs when a person’s own immune system mounts a defense (autoimmune) against parts of that person’s own brain, leading to pathological damage to the brain (encephalopathy). Autoimmune encephalopathies comprise a large number of syndromes, many of which have only recently been identified. Unfortunately, for many years, such syndromes were not readily classified, and many persons who mounted these immune responses were not treatable. Indeed, many were considered delusional and were institutionalized. Fortunately, today, there are many treatments for this diverse set of syndromes, even when the underlying cause is not known.
In these syndromes, a person’s own immune system mounts an immune response to portions of the person’s own brain. Among the results of this unusual response is the production of autoantibodies (antibodies against one’s own self). As part of this immune response, as with many other immune responses, swelling occurs. In this case, the swelling is within the substance of the brain. This swelling disrupts the normal processing within the brain, and can lead to a variety of symptoms, including, for example, (1) inability to process simple information; (2) inability to keep track of time; (3) delusions – believing things that are completely untrue, yet you believe to be true and (4) paranoia – irrationally believing that people and the environment are actively working against you and may harm you.
Many types of autoimmune encephalopathies have been described. Indeed, because of this wide spectrum, the disorder itself is difficult to classify. However, finding a specific autoantibody in the person’s blood can identify some disorders. Among these syndromes are those where a person mounts an immune response and produce autoantibodies to their own nervous system components that are vital for processing various types of nervous activities within the brain. These include a receptor for the neurotransmitter glutamate, the NMDA (N-methyl-D-aspartic acid) receptor, and an ion channel that is important for neuronal communication, the potassium channel. Presence of autoantibodies to these types of components of the nervous system is consistent with these types of autoimmune encephalopathies.
Other immune-mediated encephalopathies also exist such as post-infectious encephalitis. These encephalopathies are not triggered by a person mounting an immune response to their own body; rather, they are a result of a delayed response following a person’s immune response to an infection. These may follow a mild viral infection or may, in rare cases, result from an immune response to a vaccination.
Another autoimmune encephalitis key group is paraneoplastic neurological syndrome. This is described as the response of cancer-fighting agents in the body’s immune system fighting against tumor cells in the body. This disorder may arise from tumor or from immune cross-reactivity between malignant and normal tissues Treatment of the underlying cancer and other interventions may prevent further damage, improve symptoms and result in better quality of life.
For general information about autoimmune encephalopathies, go to: http://www.nhs.uk/Conditions/Encephalitis/Pages/Causes.aspxand
Specific information may be found at:
Moscato EH, Jain A, Peng X, Hughes EG, Dalmau J, Balice-Gordon RJ. (2010) Mechanisms underlying autoimmune synaptic encephalitis leading to disorders of memory, behavior and cognition: insights from molecular, cellular and synaptic studies. Eur J Neurosci 32:298-309. PMID: 20646055