Here is a great piece from the Alzheimer’s Association that discusses important aspects of dementia and how to deal with increased aggressive behavior.

The chief cause of behavioral symptoms is the progressive deterioration of brain cells. However, environmental influences can also cause symptoms or make them worse. Aggression can be caused by many factors including physical discomfort, environmental factors and poor communication. Aggressive behaviors can occur suddenly, with no apparent reason, or can result from a frustrating situation. If the person is aggressive, consider the following:

Physical discomfort

• Is the person tired because of inadequate rest or sleep?
• Are medications causing side effects? Side effects are especially likely to occur when individuals are taking multiple medications for several health conditions.
• Is the person unable to let you know he or she is experiencing pain?

Environmental factors

• Is the person overstimulated by loud noises, an overactive environment or physical clutter?
• Does the person feel lost ?

Poor communication

• Are you asking too may questions or making too many statements at once?
• Are your instructions simple and easy to understand?
• Is the person picking up on your own stress and irritability?
• Are you being negative or critical?

The best way to react is then: to back off and ask permission; use calm, positive statements; reassure; slow down; add light; offer guided choices between two options; focus on pleasant events; offer simple exercise options, try to limit stimulation.
You can also say things such as: May I help you? Do you have time to help me? You’re safe here. Everything is under control. I apologize. I’m sorry that you are upset. I know it’s hard. I will stay with you until
you feel better.