Can you get alzheimer's disease by shaking your head or concussions?

No: Concussions may cause chronic traumatic encephalopathy which is different from alzheimer's disease. However, some studies indicate the head injury increases the risk of developing alzheimer's disease.

A little complex: Standard head shaking is harmless, unless you injure your neck. Repetitive head injury such as many concussions can cause post-traumatic encephalopathy, which is seen in many professional athletes. There is a relationship with head trauma and Alzheimer's pathology, but is not anatomically in same locations as standard alzheimer's.

A bit complicated: Repeated head injury is described as a risk factor for alzheimer's. However, it more commonly results in a form of dementia called chronic traumatic encephalopathy (cte) which shares some of the clinical features of alzheimer's. Some of the abnormal proteins that deposit in the brains of alzheimer's are also seen in cte. However, these changes can often be differentiated from typical alzheimer's.