Dementia is a loss of mental abilities so severe it interferes with a person's ability to function normally at work or in social settings. It is characterized by impairment of short- and long-term memory and disintegration of personality due to impaired insight and judgment.

A biologically based brain condition, dementia may be progressive, static or reversible, depending on the particular conditions of the disease and its treatment. Static dementia usually follows a single major injury like a severe head trauma or heart attack. It does not progress in severity, but remains stable in degree of impairment. Progressive dementia, however, does progress in time and accompanies several major brain disorders.

Dementia is associated with various central nervous system disorders, including Alzheimer's disease, schizophrenia, Huntington's disease, and Parkinson's disease. Dementia is also associated with AIDS in its late stages.

Whether it occurs suddenly, as in static dementia, or gradually, as in progressive dementia, the condition causes many disabling symptoms, including:

• Memory disturbance
• Personality change
• Impairment of judgment and control of impulses
• Confusion or disorientation
• Depression, paranoia or anxiety
• Diminishing initiative
• Deterioration of intellectual capacity
• Obsessive behavior or paranoia
• Delusions or psychotic episodes

One million Americans are presently incapacitated by dementia, which is found primarily in the elderly, but can occur at any age. Researchers predict the number of people with dementia will rise considerably with the increasing prevalence of AIDS, since 50 percent of AIDS patients develop dementia by the late stages of the disease.