It is hard to know. It is hard to know in every situation why this occurs. Sometimes there is a long pattern of domestic violence in the relationship, caregiver personal problems also increase the risk as does social isolation. The more in recent term is "elder mistreatment" which includes physical abuse, and also neglect as well as financial, emotional, and sexual abuse. If you suspect this is occuring report it!
Vulnerable-exposed. Elder abuse is when older persons are abused, neglected, and exploited. Many elders are physically handicapped, are vulnerable, dependent, and targets of others' frustration and anger (such as family members, some nursing home personnel, etc.). When a person does not know how to handle their own fear, anger or frustration, they turn it outwards on someone who cannot easily defend him or herself.