Dementia covers a broad category of brain diseases.
Alzheimer's disease is the most common among them.
Health authorities say Alzheimer's disease makes up the majority of cases followed by vascular dementia and other degenerative diseases.
The first sign of early Alzheimer's is when you begin to experience forgetfulness associated with aging.
But simple memory lapses do not necessarily mean dementia.
If you are confused when expressing your thoughts, performing complex tasks or traveling alone to unfamiliar places, this means a decline in cognition and thus the onset of dementia.
"If I give you a hint and you recall whatever you forgot, it could be a natural memory lapse. But if you still cannot remember even after the hint, it could be a sign of early dementia. If you have dementia, you will also have problems communicating, calculating things or navigating the roads."
Experts say people severely hard of hearing are four times more likely to develop dementia than other people.
"We hear and learn from the outside world. Hearing stimulates our brain but if we can't hear, there's no stimulation. If we can't talk, we remain disconnected and alone. We spend less time using our brain, and dementia begins to develop."
Health professionals recommend eating healthily and paying attention to the warning signs of dementia.
This means eating low-fat meat along with fish and vegetables and being mindful of forgetting daily routines, such as taking pills.
Doctors also say caregivers should let dementia patients do things for themselves, rather than have caregivers do everything for them.
Choi Si-young, Arirang News.