A gradual deterioration of mental functioning affecting all areas of cognition, including judgment, language, and memory.

Dementia generally occurs in the elderly, although it can appear at any age. Several substantial studies have been done to determine its prevalence, and in 1991 a major study was conducted which found that dementia occurred in just over 1 percent of the population aged 65 to 74; in approximately 4 percent in ages 75 to 84; and more than doubling to 10.14 percent in persons 85 and over. Other studies have concluded that many as 47 percent of people over 85 suffer from some form of dementia. Prevalence rates tend to be comparable between the sexes and across sociocultural barriers, such as education and class. It is also worth noting that, despite what is often commonly thought, dementia is not an inevitable consequence of