There is much confusion about these terms as they are often used interchangeably.
Dementia is not a disease in itself, but rather a word that describes a group of symptoms all having to do with cognition: memory, language, attention and problem solving. Dementia can be reversible or progressive. Causes of reversible dementia include medication side effects, infection, vitamin deficiencies, metabolic changes, etc.
The most common types of progressive dementia include Alzheimer’s disease, vascular dementia (strokes), Lewy Body Dementia and Frontal Temporal Dementia.
The most common form of dementia is Alzheimer’s disease, accounting for approximately 60% of the progressive types of dementia. This is one reason that the terms are used interchangeably.
Think of it this way: If you have a diagnosis of Alzheimer’s disease, a person has a type of dementia. If you have dementia, you may have Alzheimer’s disease, but it could also be one of the above mentioned or other neurological disorders.