I have lived with trauma induced brain dysfunctions for decades. I lost a great amount of memory function after concussions in 1995, 1999 and 2001. My functions were measured in 2002, 2007, and 2014. My decreased functions have stayed the same over that period of time.

The brain starts an age related deterioration in the 40's.

Studies suggest that alcohol diminishes the brain's ability to heal and grow new brain cells. So, if you mix injury with a decreased ability to heal due to alcohol, alcohol is involved in the problem. Some have compared getting badly drunk to suffering a concussion. The toxicity of the alcohol can cause a similar cascade of events in the brain. Encephalopathy can result form liver damage from alcohol.

In everything I have read about fMRI's, they are used for research with little value for treatment oriented diagnoses. In the proper hands, they may be able to suggest CTE but you would need to find a researcher familiar with CTE and fMRI's. I have never heard of an fMRI being used with NPA except in a research setting.

CTE effects everybody differently based on a wide variety of injury profiles. It has been seen in early 20's. Here is a brief description of the progression. http://www.medicinenet.com/script/ma...iclekey=157953
Absent continuing trauma, it usually progresses slowly.

Rather than being concerned about what could happen in the future, I think you should be considering what you can do now.