Concern about long-term brain affects from medium-hard MMA sparring - realistic risk?

Hi everyone, I’m a 15-year-old who is seriously considering committing to MMA training for the next few years, but I want to make a fully informed decision before starting.

The gym available to me trains MMA 4–5 times per week. Most training is technical, grappling, conditioning, etc., but striking sparring does occur. Sparring is usually medium intensity (around 50–60% power), but occasionally there are partners who go harder (70–80%, sometimes briefly higher). There are no knockouts in training, but head movement and rotation do happen, and the hits are real.

I’m not worries about facial cuts, body injuries, or pain — my main concern is the brain. Specifically, potential long-term cognitive effects like slower information processing, reduced reaction speed, or subtle neurological changes caused by repeated sub-concussive impacts.

I understand that CTE is mostly associated with professional boxers or athletes with many years of frequent concussions. I’m not planning to compete professionally right now, and I’m mainly asking about training exposure only, without knockouts or diagnosed concussions.

My questions are:

From a scientific and practical standpoint, is medium-intensity sparring over a few years realistically associated with long-term cognitive decline?

How significant is the role of rotational acceleration vs pure impact force?

Is occasional harder sparring enough to meaningfully increase risk, or does damage mostly occur at much higher volumes and intensities?

Are there any realistic thresholds (frequency or intensity) beyond which neurological risk becomes substantial?

I’m asking in good faith and genuinely trying to weigh risk vs reward before committing.I've notice no one barely talks about this and you can't find examples on internet with right explanation. Any insight from experienced fighters, coaches, or people familiar with the research would be greatly appreciated.

Thanks.