January 14, 2019Neurology
Alzheimer's disease (AD) affects about 5.7 million people in the United States alone, at an estimated annual cost of $232 billion.
According to an article published in Acta Neuropathologica (December 2018), an ultrasensitive test has been developed that detects a corrupted protein associated with AD and chronic traumatic encephalopathy (CTE), a condition found in athletes, military veterans, and others with a history of repetitive brain trauma. According to the authors, this advance could lead to early diagnosis of these conditions and open new research into how they originate. In the article, the authors, explain how they adapted a diagnostic test originally developed for prion diseases to detect abnormal clusters of tau protein. Like other proteins involved in neurological diseases, tau protein clusters can seed themselves and contribute substantially to the disease processes of Alzheimer's and CTE. The study involved brain samples from 16 Alzheimer's patients, two boxers with CTE, and numerous control cases involving other brain diseases.
The test is called AD RT-QuIC: Alzheimer's disease real-time quaking induced conversion. The test is also extremely sensitive. For example, if a pinhead-sized sample of brain tissue from an Alzheimer's patient were pulverized and diluted into a thousand gallons of liquid, the test still could detect tau seeds in a pinhead-sized volume of that dilution.
Scientists at the National Institute of Allergy and Infectious Diseases (NIAID) developed RT-QuIC about a decade ago to detect Creutzfeldt-Jakob (CJD) and other prion diseases. Since then, they have repeatedly improved and adapted it to detect other neurological diseases, such as Parkinson's and dementia with Lewy bodies. The test, which already is used in clinical settings to diagnose sporadic CJD, is noted for its rapid and accurate results. Their latest findings could be a major advance for AD diagnostics because the study points to tau seeds as potential biological markers for AD in the brain. Since one approach in the treatment of AD is to test therapies to slow the accumulation of tau clusters and the progression of neurological disease, there is a need for more sensitive and accurate tests to better select clinical trial participants and assess whether new therapeutic strategies work as hoped.