Introduction: What do we know about head injuries and neurodegenerative diseases?
Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with repetitive head impacts and has been linked particularly to long-term participation in contact sports. It is characterized by the abnormal accumulation of a protein called tau in the brain and can only be definitively confirmed through neuropathological examination of brain tissue.
Creutzfeldt–Jakob disease (CJD), in contrast, is a rare and rapidly progressive neurodegenerative disease associated with prions, which cause severe damage to brain tissue.
Although these two conditions involve different pathological processes, little is currently known about their possible coexistence.
At the Sant Pau Memory Unit, we participated in a study investigating this question by examining the presence of chronic traumatic encephalopathy in individuals with neuropathologically confirmed Creutzfeldt–Jakob disease.
What did we do in this study?
We participated in a retrospective study examining brain tissue samples from 212 individuals with neuropathologically confirmed Creutzfeldt–Jakob disease.
The study was conducted at the Neurological Tissue Bank of Hospital Clínic-IDIBAPS. Researchers examined samples from the hippocampus and frontal cortex to identify lesions characteristic of chronic traumatic encephalopathy.
Immunohistochemical techniques were used to detect the abnormal accumulation of phosphorylated tau protein in brain tissue. When initial findings suggested the possible presence of CTE, additional brain regions were examined in accordance with international consensus criteria.
The clinical histories, sporting backgrounds and neuropathological findings of the confirmed cases were subsequently reviewed.
The research involved collaboration between teams at Hospital Clínic-IDIBAPS, the University of Barcelona, Boston University and other healthcare and research institutions.
Main findings: Three cases with both conditions
The analysis identified three cases of chronic traumatic encephalopathy among the 212 individuals studied, representing 1.4% of the cohort.
All three individuals showed severe neuropathological changes consistent with chronic traumatic encephalopathy. They were men with a history of long-term participation in contact sports:
- Two were former soccer players, one of whom had competed at an elite level.
- The third was a former rugby player.
All three had started playing sports during childhood or adolescence and had continued for many years.
The study also found that the clinical presentations of Creutzfeldt–Jakob disease differed across the three cases. Neuropathological examination confirmed the coexistence of both conditions despite differences in clinical presentation and the pathological characteristics of CJD.
Importantly, these findings do not establish a causal relationship between the two diseases or determine the prevalence of chronic traumatic encephalopathy in the general population. The observed percentage applies exclusively to the cohort examined.
Why is this research important?
Our findings provide new evidence on the possible coexistence of chronic traumatic encephalopathy and Creutzfeldt–Jakob disease, two neurodegenerative conditions with distinct biological mechanisms.
Identifying these three cases highlights the importance of detailed brain tissue examination to detect different neuropathological processes that may coexist in the same individual.
The study also contributes to our understanding of neurodegenerative diseases associated with repetitive head impacts and raises new questions about potential biological mechanisms shared by these conditions.
However, further research is needed to determine whether a relationship exists between the two diseases and to better understand the factors that might contribute to their coexistence.
This work highlights the value of collaboration between clinical and neuropathological research teams in advancing our understanding of neurodegenerative diseases.
Further information
Original article: Chronic traumatic encephalopathy in a neuropathologically confirmed Creutzfeldt–Jakob disease cohort.
Authors: Lluc Bertran, Iban Aldecoa, Arlène Sindikubwabo, Núria Vidal, Rafael Blesa, Mercè Martínez-Corral, Carlos Nos, Verónica Santiago, Andrea González, Álex Iranzo, Christopher J. Nowinski, Ann C. McKee, Raquel Sánchez Valle and Laura Molina-Porcel.
Journal: Brain Pathology (2026).
First published online: 14 October 2026.
DOI: https://doi.org/10.1111/bpa.70156
Participating institutions: Sant Pau Memory Unit, Hospital de la Santa Creu i Sant Pau, Sant Pau Research Institute (IR Sant Pau), Hospital Clínic-IDIBAPS, University of Barcelona, CIBERNED, Boston University and other collaborating institutions.