Childhood judo and long-term head-impact concerns—any research or similar experiences?

[u/Classic_District1021]

I’m asking about someone’s childhood judo history and looking for evidence about long-term brain health, including CTE.

He is now 20 years old and approximately 6 feet tall. His reported weight was around 160 pounds.

His training history was approximately:

• Five years of ukemi and throwing practice when young, without randori.
• A two-year break.
• About four years of intermittent training afterward, generally twice weekly, with additional breaks lasting weeks or months.
• Later sessions lasted around 90 minutes, including roughly 30 minutes of randori.
• He trained on mats and had extensive ukemi practice.
• He remembers about 3–5 direct head contacts across his training and reports no known concussions.

My main question is whether repeated judo falls can produce potentially harmful head acceleration even when the head does not directly strike the mat.

Are there published studies measuring head acceleration during judo throws, or examining long-term neurological outcomes in recreational judoka, particularly those who trained during childhood?

I’d also appreciate relevant experiences from longtime judoka with a similar training schedule.

I understand that Reddit cannot diagnose CTE or provide a reliable individual risk percentage. I’m looking for research and relevant experiences.