Dementia is a group of symptoms brought on by a gradual degeneration of brain cells and in turn, a person’s cognitive functions, such as memory, concentration and judgment. Dementia is the result of organic damage to the brain (as is with Alzheimer's disease), and is more common in older adults. However, it can occur at any stage of adulthood. Similar to most forms of cognitive dysfunction, one’s higher mental functions are usually affected first. Often treatable to some degree, depending on the cause of the disease, symptoms of dementia are classified as either reversible or irreversible.