Major types of dementia include cortical dementia and subcortical dementia, according to WebMD. They are grouped depending on the part of the brain they attack.
Cortical dementia occurs when a disorder affects the cerebral cortex, which is the part of the brain that controls thinking, explains WebMD. Cortical dementia usually causes loss of memory and loss of the ability to recall and understand language. Examples of cortical dementia include Alzheimer's disease and Creutzfeldt-Jakob disease. Subcortical dementia, on the other hand, occurs when brain sections located under the cortex fail to function normally, and they include Parkinson's disease and Huntington's disease, among others. Subcortical dementia may cause symptoms such as change in thinking speed.