Dementia

Dementia is a progressive or persistent loss of cognitive function, which can be caused by any of a number of diseases and conditions. The specific symptoms may include difficulties with memory, ability to understand and use language, spatial orientation, and limitations in executive function, such as the ability to plan and loss of impulse control. People who have a dementing illness may also experience behavioral difficulties and changes in mood.

The most common cause of dementia is Alzheimer's disease, and the terms are often used interchangeably. While the precise cause of Alzheimer's disease is not well understood, it is characterized by a cascade of injury to the brain cells resulting, ultimately, in the catastrophic loss of many brain functions. There are several variants to Alzheimer's disease, most notably that characterized by early onset versus later onset. Early-onset Alzheimer's, which can occur as early as in the third decade, is often triggered by one of several rare, inherited autosomal dominant genetic abnormalities. More common is late-onset Alzheimer's disease, which may be diagnosed as senile dementia of the Alzheimer's type. Alzheimer's disease is relentlessly progressive and will eventually result in such severe neurological damage that people are unable to walk, swallow, or control their movements.

The next most common cause of dementia is vascular assault to the brain, also known as transient ischemic attacks (TIAs), or small strokes. Vascular dementia can sometimes be controlled by treating the underlying vascular conditions, such as high blood pressure. The 45% of people with dementia have been found to have both vascular dementia and Alzheimer's disease.

Many other neurological diseases, such as Parkinson's and multiple sclerosis and Huntington's, are associated with dementia symptoms, and some are infectious diseases, such as HIV/AIDS and Creutzfeld-Jakob disease. Head injuries, excessive alcohol use, and other factors may also result in dementia.