Does Substance Abuse Cause CTE Pathology? Global Expert Weighs in to Debunk Misguided Theory

By Dr. Chris Nowinski, Concussion Legacy Foundation co-founder and CEO

As the lead author of the 2nd through 5th Consensus Statement on Concussion in Sport, Dr. Paul McCrory may be the most influential neurologist in sports over the past 20 years. The Statement is famous for both its extraordinary conflicts of interest and for downplaying the link between head impacts and CTE.

The conference that produces updated statements is funded or organized by international sports governing bodies like FIFA and the IOC and 32 of the 36 authors have financial ties to organized sports. Some have suggested that their statement on CTE, "a cause-and-effect relationship has not yet been demonstrated between chronic traumatic encephalopathy and sport related concussion and exposure to contact sports” is critical to successfully defend class-action lawsuits from former athletes. (In contrast, the CDC CTE Fact Sheet says evidence demonstrates a cause-and-effect relationship).

Over the last month, McCrory has had two editorials retracted for plagiarism, faces additional allegations of plagiarism, and is being asked to explain how he treated athletes with concussion symptoms during a time the Medical Board of Australia said he was not allowed  perform neurodiagnostic procedures. I also wrote a blog about how he has also misrepresented BU’s research in public talks.

While we’re looking into McCrory’s influence on the global CTE conversation, would you be surprised to learn he is a was also one of the key promoters of the theory that CTE can be caused by the use of opioids? Professional sports organizations embraced it and repeated it because they know their athletes suffer injuries that often require surgery and the use of painkillers. In 2015, McCrory was senior author on an opinion piece that questioned the link between CTE and sports, claiming:

“The correlation between opioid abuse and hyperphosphorylated tau deposition is well described, and should be factored as a key variable in any assessment of causation [in CTE].”

We reached out to the world’s expert on how opioids and alcohol impact the brain neuropathologically, and in the following video he debunks McCrory’s nonsensical claim that CTE could be caused by substance abuse. Dr. Gabor Kovacs is an internationally renowned neuropathologist and researcher in the field of neurodegenerative diseases. In 2021, he received the Alfred Meyer Memorial Lecture and Prize from the British Neuropathological Society for his expertise on tau-related conditions. He is currently affiliated with the University of Toronto and the University Health Network (UHN), where he holds numerous roles including consultant Neuropathologist  at the Laboratory Medicine Program at the UHN, Principal Investigator at the Tanz Centre for Research in Neurodegenerative Disease, and Senior Scientist at the Krembil Brain Institute.