We all forget things as we get older. Mild memory loss is common in older adults and as long as it doesn't affect their daily lives, isn't usually a problem. But memory loss that gets worse and affects daily life may be a sign of dementia. Dementia can cause problems with memory and how well a person is able to think and plan. Alzheimer's disease is the most common cause of dementia. Usually dementia gets worse over time. How long this takes is different for each person. Some people stay the same for years. Others lose skills quickly. Follow the links below to find WebMD's comprehensive coverage about dementia, what it looks like, how to treat it, and much more.