Not all brains are equal, especially for those that have been knocked about significantly more than others. The risk of dementia becomes especially high for people who are exposed to head trauma. This can of course include automobile accidents or otherwise unforeseen tragedies, but especially those in high-impact sports who are chronically experiencing hits to the skull. Dementia pugilistica (though originating from boxing/pugilism) is an umbrella term for what can happen to professional athletes who play sports such as football, hockey, ruby, and of course boxing. Boxers are the leading demographic of DP, with about 20% of professional boxers ending up with some form dementia.
A note here about DP: any brain “malfunctioning” can essentially be attributed to damage to the brain, which means people who have suffered severe or repeated head trauma can go on to have dementia in its specific forms (Alzheimer’s disease, especially, but also Parkinson’s), as well as dementia pugilistica, which started the whole process of degeneration.
Another thing to keep in mind about dementia pugilistica: it seems that some athletes develop Alzheimer’s disease while others don’t, even though they had the same exposure to head trauma. Though few studies have determined who exactly is more like to develop which kinds of dementia, there is a likely explanation in genetic inheritance. Athletes who have the apoE4 gene seem to be more prone to dementia, and increasingly frequent or intense exposures to head trauma only serves to secure the likelihood of dementia. But most people don’t know whether or not they have this particular apoE4 gene (or how to get testing to identify the gene). It’s also out of our control whether we have this gene in the first place. But the factor that can be controlled is reduction in the intentional brain injury department, which is the real trigger for dementia pugilistica.