. . "Dementia is a syndrome, usually of a chronic or progressive nature, caused by a variety of brain illnesses that affect memory, thinking, behavior and ability to perform everyday activities.The total number of people with dementia worldwide in 2011 was estimated at 35.6 million. , 58% live in low- and middle-income countries, and this proportion is projected to rise to 71% by 2050.The total number" . .