At first, memory loss and inability to think clearly may bother the person with dementia. Later, disruptive behavior and other problems may start. The person with dementia may not be aware of those problems. Dementia is caused by the loss of brain cells. A head injury, a stroke, a brain tumor or a problem like Alzheimer's disease can damage brain cells.
Some people have a family history of dementia.
Many of the problems are due to loss of memory. Some common signs of dementia are listed below. Not everyone with dementia has all of these signs. Recent memory loss. All of us forget things for a while and then remember them later.