According to the Alzheimer's Association, dementia is not a specific disease. It's an overall term that describes a group of symptoms associated with a decline in memory or other thinking skills severe enough to reduce a person's ability to perform everyday activities. The most common types of dementia are Alzheimer's disease, dementia with Lewy Bodies, Frontotemporal dementia and Parkinson's disease. Generally, it will affect the patient's cognitive ability, language proficiency, calculations, judgment, abstract thinking, concentration and many more. Additionally, symptoms like obstructive behaviors, change in personality, delusions or hallucinations might also occur. These symptoms could possibly affect the patient's interpersonal relationships and work abilities in a negative way.