King Henry VIII was often a bad boy. I mean, he had two of his many wives executed, for starters. But he was an historical giant—-he took on the Pope and established the Church of England—no small feat in the 1500’s.
But he also developed erratic behavior later in his life. Many date his significant personality change to a head injury following a fall beneath a horse in a 1536 jousting match. He apparently remained unconscious for two hours.
But could a blow to the head cause a dramatic personality change? Absolutely.
There are many types of brain injuries that could lead to such an outcome: Concussions (usually multiple such injuries are needed before personality changes would occur—if at all); Cerebral contusions (brain bruises); intracerebral bleeds (bleeding into the brain tissue; and subdural hematomas (bleeding in the space between the brain and the skull). In Henry’s case, I suspect the later might be the case.
Subdural hematomas follow blows to the head and here blood collects in the dural space—between the brain and the skull. It can be small and inconsequential or larger and compress the brain. It can occur immediately or be delayed by hours, days, weeks, and even months. The increased pressure on the brain can lead coma and death. Less dramatically, it can cause headaches, visual impairment, weakness, poor balance, sleepiness, confusion, and, yes, personality changes.