It is not unusual to occasionally forget where you put your keys or glasses, where you parked your car, or the name of an acquaintance. As you age, it may take you longer to remember things. Not all older adults have memory changes, but they can be a normal part of aging. This type of memory problem is more often annoying than serious.
Memory loss that begins suddenly or that significantly interferes with your ability to function in daily life may mean a more serious problem is present.
Dementia is a slow decline in memory, problem-solving ability, learning ability, and judgment that may occur over several weeks to several months. Many health conditions can cause dementia or symptoms similar to dementia. In some cases dementia may be reversible. Alzheimer's disease is the most common cause of dementia in people older than age 65.
Delirium is a sudden change in how well a person's brain is working (mental status). Delirium can cause confusion, change the sleep-wake cycles, and cause unusual behavior. Delirium can have many causes, such as withdrawal from alcohol or drugs or medicines, or the development or worsening of an infection or other health problem.