Dementia is not a specific disease. It’s an overall term that describes a wide range of symptoms associated with a decline in memory or other thinking skills severe enough to reduce a person’s ability to perform everyday activities. Alzheimer’s disease accounts for 60 to 80 percent of cases.
People with dementia can become apathetic or uninterested in their usual activities, or may have problems controlling their emotions.
Because people with dementia may lose the ability to remember events or fully understand their environment or situations, it can seem as if they’re not telling the truth, or are wilfully ignoring problems.