Autoimmune Dementia

Last week we explained that autoantibodies can attack the brain, causing autoimmune encephalitis (AE). This form of neuroinflammation is characterized by various symptoms, including psychosis, catatonia, and seizures that are often misdiagnosed as a primary psychiatric disorder.

However, what we didn’t reveal is that a subset of these cases can present as dementia without these classic AE symptoms. This suggests there is a separate category of dementia not caused by old age-driven neural degeneration. In 2010, Dr. Sean Pittock and colleagues at the Mayo Clinic coined the term autoimmune dementia to describe cognitive decline attributed to autoimmunity.

Here is the good news. The research suggests that early identification and treatment of autoimmune dementia can reverse the memory decline. The bad news is misdiagnosis is far too common.

In this article, we will teach you the signs and symptoms of autoimmune dementia to help you advocate for proper testing and better outcomes for yourself or a loved one.

Data describing the prevalence of this form of severe memory decline are still being collected. However, one Dutch nationwide observational cohort study assessing all AE cases between 1999 and 2019 found that 38% (67/175 cases) of patients with autoimmune encephalitis met clinical criteria for dementia without classic autoimmune encephalitis symptoms (at early disease onset).

Another study by a Swedish research group approached the question differently. They wanted to know how many individuals visiting a memory clinic were unknowingly suffering from autoimmune forms of dementia. After screening 1021 patients from the clinic for known brain-targeting autoantibodies, they found that 11 patients (1.07%) were positive.

Granted, it’s difficult to extrapolate how many people might have an autoimmune form of dementia based on this one study. But consider that researchers suspect “110 of every 100,000 people age 30 to 64 years, or about 200,000 Americans in total, have younger-onset dementia.” How many of these individuals actually have a misdiagnosed form of autoimmune dementia that is (partly) reversible when treated correctly?