Alzheimers Home > More Facts on Dementia
Is Memory Loss a Symptom of Dementia?While memory loss is a common symptom of dementia, memory loss by itself does not mean that a person has dementia. Doctors will only diagnose it if two or more brain functions -- such as memory, language skills, perception, or cognitive skills (including reasoning and judgment) -- are significantly impaired without loss of consciousness.
(Click Symptoms of Dementia for more information about symptoms. For more information about how doctors diagnose it, see Dementia Diagnosis.)
How Does It Progress?There are many disorders that can cause dementia. Some disorders, such as Alzheimer's disease, can lead to a progressive loss of mental functions, while other types of dementia (about 10 percent) can be halted or reversed with appropriate treatment. With Alzheimer's disease and many other types, disease processes cause many nerve cells to stop functioning, lose connections with other neurons, and die. In contrast, normal aging does not result in the loss of large numbers of neurons in the brain.
There are many different ways to classify dementia disorders. These classification schemes attempt to group disorders that have particular features in common, such as whether they are progressive or what parts of the brain are affected. Below is one example of a classification system that may be used:
- Cortical dementia -- occurs when brain damage primarily affects the brain's cortex (outer layer). Cortical dementias tend to cause problems with memory, language, thinking, and social behavior.
- Subcortical dementia -- affects parts of the brain below the cortex. This type tends to cause changes in emotions and movement in addition to problems with memory.
- Progressive dementia -- gets worse over time, gradually interfering with more and more cognitive abilities. One example of this type is Lewy body dementia.
- Primary dementia -- dementia such as Alzheimer's disease that does not result from any other disease.
- Secondary dementia -- occurs as a result of a physical disease or injury.
Some types fit into more than one of these classifications. For example, Alzheimer's disease is considered both a progressive and a cortical dementia.
(Click Dementia Types for more information.)