Can you know for sure if a person has dementia before a brain ct?

Belligerence, making threats, hitting, all can be symptoms of dementia. They can also have other causes.

Are you taking care of your mother, Jenwide? Has she been diagnosed with dementia? Has she seen a doctor since she has had this threatening behavior?

Give us a little more background information, so we can answer more specifically.

Are you in any danger from your mother? For example, she threatens to shoot you -- does she have access to a gun?