In the United States, between 5 and 8 percent of people over age 65 have a type of dementia, with an estimated 50 percent of people 85 or over having dementia, according to the Cleveland Clinic. The term “dementia” encompasses a group of symptoms, such as changes in thinking, personality and behavior. The types of dementia can be classified based on where in the brain the damage occurs or how the dementia occurred. Examples of these classifications of dementia include primary dementia, secondary dementia, cortical dementia, subcortical dementia and progressive dementia.
Primary Dementia: With primary dementia, the patient does not have the symptoms as a result of another disease. An example of a primary dementia is Alzheimer’s disease, which accounts for 50 to 70 percent of dementia cases, according to the Cleveland Clinic.
Secondary Dementia: If a patient has secondary dementia, then the dementia resulted from an injury or another disease. Several different issues can lead to secondary dementia, such as brain infections, progressive supranuclear palsy and multiple sclerosis. While many types of dementia are degenerative, meaning the damage cannot be reversed, some types of secondary dementia can be stopped or reversed. However, this depends on the cause being identified soon.
MedlinePlus noted that reversible causes of dementia include low levels of vitamin B-12, brain tumors, chronic alcohol abuse, changes in calcium or sodium levels, or the use of certain medications. If the cause is a medication, patients should talk to their doctors before discontinuing the medication on their own.
Cortical Dementia: If a patient has cortical dementia, the area of the brain damaged is the brain’s cortex, which is the outer layer of the brain. This type of dementia can result in memory impairment and aphasia, a language disorder in which the patient may have trouble understanding language or producing coherent speech. Examples of cortical dementias include Alzheimer’s disease and Creutzfeldt-Jakob disease.