Largest population study to date led by University of Sao Paulo researchers finds CTE is rare in general public

Study of more than 1,100 brains donated to aging study reinforces CTE is uncommon outside of those exposed to repetitive head impacts

Jacksonville, FL — A new study, led by Lea T. Grinberg, MD, PhD, while at the University of California, San Francisco (UCSF), and University of Sao Paulo’s Roberta Diehl Rodriguez, MD, PhD found that the brain disease chronic traumatic encephalopathy (CTE) is rare in the general population. The study, published Monday in the Journal of Neuropathology & Experimental Neurology, examined more than 1,100 consecutive brains donated to a study on aging. The results add important clarity to public understanding of CTE and reinforces decades of research showing that CTE is primarily associated with repetitive head impacts (RHI), not everyday life.

Researchers conducted an exhaustive neuropathological analysis of 1,151 individuals who died between 2004 and 2022 from a large, diverse, population-based autopsy cohort at the Biobank for Aging Studies at the University of São Paulo in Brazil. After reviewing nearly 15,000 brain tissue slides, the team identified CTE pathology in just seven cases, approximately 0.6% of the population. Six of the seven were male, consistent with other studies and data showing that historically, men are far more likely to be exposed to RHI through contact and collision sports.

“This study shows CTE is a rare disease in the general population,” said Dr. Grinberg, senior author of the study. “Current scientific evidence indicates that CTE is most commonly identified in individuals with a history of repetitive head impacts, such as those who participated in contact sports or served in the military. While research is ongoing, CTE appears to be uncommon in individuals without known exposure to repeated brain trauma.” Now the director of the Brain Bank Modernization at Mayo Clinic in Florida, Dr. Grinberg conducted the research while at UCSF.

“While it’s an important scientific finding to confirm that CTE is rare in such a large cohort, from the perspective of public health, the prevalence should be extremely concerning,” said Chris Nowinski, PhD, co-author of the study and CEO of the Concussion & CTE Foundation. “CTE is a preventable environmentally acquired disease, and the youngest person diagnosed to date died at age 17. With more than 250 million adults over the age of 17 in the United States, this study would suggest around 1.5 million Americans have CTE. That would make it among the most common neurodegenerative brain diseases in the country.”

The study represents the most demographically diverse populations ever studied for CTE. Ages at death ranged from 30 to 105 with an average age of 74. 51% were male, 68% were white, and 44% were middle-class. Twenty-six percent abused alcohol, and 54% were smokers. Prior population studies have also found a CTE prevalence between 0% and less than 1%. A question on RHI exposure history was only added late in the study, and both participants whose RHI history was known were soccer players.

This study was funded by the Concussion & CTE Foundation and the Alzheimer’s Association (AARF 18-566005) with the support of the Biobank for Aging Studies and the LIM-22 of the University of Sao Paulo.

Read more about the study here: https://academic.oup.com/jnen/advance-article/doi/10.1093/jnen/nlaf150/8454899.

About the Biobank for Aging Studies:

The Biobank for Aging Studies (BAS) was founded in 2004 by a board of specialists, including Dr. Grinberg, at the University of Sao Paulo. Besides being the largest brain bank in Latin America, the BAS is a unique population-based collection that receives brain donations from individuals who underwent autopsy in the Sao Paulo Autopsy Service. Due to its valuable collection enriched with cases in early stages of neurodegenerative disease, the BAS has contributed to a wide range of research projects in aging and neurodegeneration during the last 20 years.