AGING
July 24, 2012

Dementia As An Autoimmune Disorder

One form of dementia may be the result of the immune system going haywire. Luckily, there might be a treatment.

As dementia plagues more and more of the aging population (Alzheimer’s disease alone is projected to affect upwards of 80 million people by the year 2030), researchers are scrambling to determine the causes of the various forms of the disease. A new study suggests that dementia may occasionally occur when the body’s immune system attacks the cells of the brain, suggesting that some dementias, at least, may be akin to autoimmune diseases.

Earlier research had suggested that people with a certain form of immune disorder can have can have symptoms of frontal and temporal lobe dysfunction, which include “impulsivity, behavioral disinhibition, poor memory, attention, and planning.” This seems to occur because antibodies are attacking a particular type of receptor (the NMDA receptor) near the synapses of the brain cells. This form of immune disease is dubbed anti-NMDAR encephalitis.

One patient with anti-NMDAR encephalitis underwent immune therapy: Afterwards, her cognitive/behavioral symptoms were markedly reduced.

The authors of the current study looked at a group of patients who had one of several types of neurological disorders and diseases, including schizophrenia, amyotrophic lateral sclerosis (ALS), and various forms of dementia (Alzheimer’s disease, Lewy Body Disease (LBD), and frontotemporal degeneration(FTD)). A subset of patients were found to be affected by anti-NMDAR encephalitis, mentioned earlier, in which the immune system attacks the NMDA receptors of brain cells.

The people who had this autoimmune disease had cognitive symptoms that resembled a “primary degenerative disorder” – in other words, a “true” form of dementia. One patient with anti-NMDAR encephalitis underwent immune therapy: Afterwards, her cognitive/behavioral symptoms were markedly reduced, and certain areas of her brain showed increased metabolic activity.

It’s unclear whether the immune disorder outlined here is the cause of dementia symptoms, or it is the result of a primary dementia that already exists, but the authors suggest that it’s more likely to be the former.

Dementia has been suggested to be linked to inflammation in the brain, so the idea that an immune reaction might be involved in certain forms of dementia is an exciting addition to what we know about this family of diseases. Thought it may be a small subset of patients who experience this particular form of dementia, the study’s findings are encouraging since one of the most devastating elements of dementia is that there is yet no cure.

“Through the study results, a completely new approach to diagnosing dementia can possibly result,” said study author Harald Prüß in a news release. “At the moment we are working on a follow-up study with larger test groups in order to verify our approach even further. The potential promise of this new approach is that completely new perspectives could result for an entire group of people suffering from dementia for whom no specific therapeutic option exists.”

The study was carried out at Charité - Universitätsmedizin Berlin and published in the journal Neurology.

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