What is Dementia?

(NIA) 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 daily living.

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 disorders, 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.

Other conditions that may cause memory loss or dementia include:

  • medication side effects
  • chronic alcoholism
  • tumors or infections in the brain
  • blood clots in the brain
  • vitamin B12 deficiency
  • some thyroid, kidney, or liver disorders
  • stroke
  • Parkinson’s disease
  • Sleep disturbances

Some of these conditions may be treatable and possibly reversible. They can be serious and should be treated by a doctor as soon as possible.

Emotional problems, such as stress, anxiety, or depression, can make a person more forgetful and can be mistaken for dementia. For instance, someone who has recently retired or who is coping with the death of a spouse may feel sad, lonely, worried, or bored. Trying to deal with these life changes leaves some people confused or forgetful. The emotional problems can be eased by supportive friends and family, but if these feelings last for a long time, it is important to get help from a doctor or counselor.



National Institute on Aging