Chronic Traumatic Encephalopathy (CTE) has transitioned from a rarely discussed neuropathological finding to a widely debated condition at the intersection of neuroscience, law, and forensic medicine. It is defined as a progressive tauopathy (a class of neurodegenerative diseases characterized by abnormal changes in a protein called tau), caused by repetitive head trauma, most often associated with contact sports, military exposure, or interpersonal violence. Characterized by perivascular deposits of hyperphosphorylated tau (pTau) at the depths of cortical sulci, CTE has become an increasingly prominent diagnosis in both clinical and forensic contexts.
Recent Developments in the News
Public attention to CTE has intensified in recent months due to tragic losses among high-profile athletes. In February 2025, former Australian Football League (AFL) premiership player Adam Hunter was posthumously diagnosed with CTE. His family's decision to donate his brain to science reignited debates about the adequacy of concussion protocols and whether sporting bodies have fully implemented coronial recommendations aimed at reducing risk. Around the same time, former New Zealand rugby player Shane Christie, a vocal advocate for concussion research, died unexpectedly at age 39. Christie had openly expressed concerns about his brain health, underscoring the mental health consequences and forensic significance of CTE-related deaths.
These cases illustrate the growing recognition of CTE not only as a neuropathological entity but as a social issue linked to suicide, depression, and litigation. Forensic professionals are often tasked with determining whether neuropathological findings of CTE contribute to cause or manner of death.
Clinical and Pathological Understanding
The clinical presentation of CTE is variable but typically includes cognitive decline, mood disorders, impulsivity, and in later stages, dementia. Stein, Alvarez, and McKee (2015) reinforced the concept that repetitive mild traumatic brain injury plays a central role in CTE pathogenesis, with neuropathological staging correlating to clinical severity. Post-mortem examination remains the gold standard, as no biomarker currently allows definitive in vivo diagnosis.
This forensic reliance on autopsy is supported by Byard, Tiemensma, Buckland, and Vink (2023), who emphasized that inadequate sampling or failure to consider CTE during death investigations risks underestimating its prevalence. The authors also highlighted that coroners and forensic pathologists must incorporate detailed head trauma histories into investigative protocols.
Forensic Considerations
From a legal perspective, CTE raises complex challenges. Wortzel, Brenner, and Arciniegas (2013) observed that while defense attorneys may cite CTE to explain aggression or impaired judgment, the scientific uncertainty surrounding in vivo diagnosis complicates its evidentiary weight in criminal proceedings. Nonetheless, forensic psychiatrists and neuropathologists increasingly confront cases in which CTE is offered as a contributing factor to behavior or death.
The diagnostic process is further complicated by biomarker research. While no single biomarker yet confirms CTE in life, forensic medicine has made progress in identifying biochemical correlates of brain injury. Olczak, Poniatowski, and Siwińska (2023) demonstrated that post-mortem detection of neuronal and astroglial markers in blood and urine could support the diagnosis of traumatic brain injury, laying groundwork for forensic application to CTE. Similarly, Zwirner, Kulakofsky, Fitzek, and Schröder (2022) identified forensic biomarkers of lethal traumatic brain injury, underscoring their potential role in bridging neuropathological findings and ante-mortem clinical suspicion.
Controversies and Debates
Despite mounting evidence, controversy remains regarding the scope of CTE. Some researchers argue that CTE is over-attributed to post-concussion symptoms, while others believe it is underdiagnosed. Barr (2020) described this divide as a polarization between "believers" and "deniers," cautioning against both overgeneralization and undue skepticism. Forensic medicine, in particular, must strike a balance between acknowledging CTE as a valid neuropathological entity and avoiding premature attribution of complex behaviors solely to its presence.
Future Directions
The future of CTE research lies in bridging neuropathology, biomarkers, and imaging. Advances in tau-targeted PET imaging and plasma biomarker assays may one day permit ante-mortem confirmation. Such tools would revolutionize both clinical management and forensic investigation, reducing reliance on retrospective reconstruction. In the meantime, the forensic pathologist remains the gatekeeper of CTE diagnosis, with brain autopsy and immunohistochemical staining for pTau serving as the diagnostic cornerstone.
Public policy must also evolve in response to forensic findings. Recent news reports underscore that sporting organizations have been slow to fully adopt coronial recommendations, such as reducing high-contact training or mandating independent medical observers. Forensic medicine plays a pivotal role in holding institutions accountable by documenting neuropathological patterns and clarifying causal relationships between repeated trauma and neurodegeneration.
Conclusion
Chronic Traumatic Encephalopathy embodies the intersection of neuropathology, forensic investigation, and public health. Recent athlete deaths have humanized the disease's consequences, while scientific advances continue to refine understanding of its clinical and forensic dimensions. Forensic professionals occupy a critical role, ensuring accurate diagnosis, guiding medico-legal interpretation, and contributing to policy debates grounded in scientific evidence. As research into biomarkers progresses, the hope remains that CTE will move from a retrospective diagnosis to one capable of early detection and intervention.
References
Barr, W. B. (2020). Believers versus deniers: The radicalization of sports concussion and chronic traumatic encephalopathy (CTE) science. Neuropsychology Review, 30(2), 137–144.
Byard, R., Tiemensma, M., Buckland, M. E., & Vink, R. (2023). Chronic traumatic encephalopathy (CTE)—features and forensic considerations. Forensic Science, Medicine and Pathology, 19(4), 547–555.
Olczak, M., Poniatowski, Ł. A., & Siwińska, A. (2023). Post-mortem detection of neuronal and astroglial biochemical markers in serum and urine for diagnostics of traumatic brain injury. International Journal of Legal Medicine, 137(5), 1459–1472.
Stein, T. D., Alvarez, V. E., & McKee, A. C. (2015). Concussion in chronic traumatic encephalopathy. Current Pain and Headache Reports, 19(10), 47.
Wortzel, H. S., Brenner, L. A., & Arciniegas, D. B. (2013). Traumatic brain injury and chronic traumatic encephalopathy: A forensic neuropsychiatric perspective. Behavioral Sciences & the Law, 31(6), 721–739.
Zwirner, J., Kulakofsky, R., Fitzek, A., & Schröder, A. S. (2022). Forensic biomarkers of lethal traumatic brain injury. International Journal of Legal Medicine, 136(6), 1709–1721.
