Scientists have reported a major new find in the form of a protein located in the brain that appears to be directly related to the development of Alzheimer’s symptoms.

The new protein, TDP-43, is different from previously identified proteins, tau and amyloid, known to be associated with the tangles and plaques in the brain. These tangles and plaques are known to be key characteristics of the disease. The presence of TDP-43 could even provide insight into why plaques and tangles can be present in people who do not show overt symptoms related to Alzheimer’s disease.

Knowledge of the TDP-43 protein could change the way that treatment and diagnosis of the disease are approached. Historically, the only way to diagnose Alzheimer’s was posthumously, as an autopsy was required to properly identify the presence of plaques and tangles in the brain. Advances in imaging technology have allowed for detection of amyloid and tau proteins before death, but did little to help understand how those proteins could be present without symptoms.

The study that identified the new protein’s role in dementia was conducted using 342 brains that contained plaques formed from amyloid proteins. The presence of a certain form of TDP-43 seemed to indicate a tenfold increase in the likelihood of developing Alzheimer’s. Despite the presence of plaques in all 342 brains, many of the people involved did not show signs of dementia upon their death. However, 57 percent of the people were found to have the abnormal TDP-43 protein and of them, 98 percent showed signs of dementia. This is compared to 81 percent of those without that form of the protein who showed signs of cognitive decline.

According to Dr. Keith Josephs, who headed the study, having this protein means a person is all but guaranteed to display symptoms; without it, there is nearly a 20 percent chance that someone could have Alzheimer’s, made apparent by the presence of amyloid plaques, and not demonstrate it overtly.