As defined by the National Institutes of Health, National Institute on Aging:

“Dementia is the loss of cognitive functioning-thinking, remembering, and reasoning-and behavioral abilities to such an extent that it interferes with a person’s daily life and activities. Dementia ranges in severity from the mildest stage, when it is just beginning to affect a person’s functioning, to the most severe stage, when the person must depend completely on others for basic activities of living.

Signs and symptoms of dementia result when once-healthy neurons (nerve cells) in the brain stop working, lose connections with other brain cells, and die. While everyone loses some neurons as they age, people with dementia experience far greater loss.

While dementia is more common as people grow older (up to half of all people age 85 or older may have some form of dementia), it is not a normal part of aging. Many people live into their 90s and beyond without any signs of dementia. One type of dementia, frontotemporal disorders, is more common in middle-aged than older adults.

Memory loss, though common, is not the only sign of dementia. For a person to have dementia, he or she must have:

  • Two or more core mental functions that are impaired. These functions include memory, language skills, visual perception, and the ability to focus and pay attention. These also include cognitive skills such as the ability to reason and solve problems.
  • A loss of brain function severe enough that a person cannot do normal, everyday tasks.
In addition, some people with dementia cannot control their emotions. Their personalities may change. They can have delusions, which are strong beliefs without proof, such as the idea that someone is stealing from them. They also may hallucinate, seeing or otherwise experiencing things that are not real.

The causes of dementia can vary, depending on the types of brain changes that may be taking place. Other dementias include Lewy Body dementia, Frontotemporal dementia, and Vascular dementia. It is common for people to have mixed dementia-a combination of two or more disorders, at least one of which is dementia. For example, some people have both Alzheimer’s disease and vascular dementia.”

  • Lewy Body Dementia: This form of dementia is a result of abnormal deposits of alpha-synuclein in the brain. These deposits effect the chemicals in the brain with an adverse effect on memory, thinking, sleep, and may also lead to visual hallucinations and movements similar to Parkinson’s disease.
  • Frontotemporal Dementia: Damage to neurons in the regions of the frontal and temporal lobes of the brain cause the lobes to atrophy resulting in dementia.
  • Vascular Dementia: This form of dementia is the result of lack of oxygen to areas of the brain, often caused by a stroke or a series of strokes.