What is the difference between amnesia, alzheimer’s and dementia?


Everytime I hear about these three diseases I always put them in the same box: forgetting stuff. And I never really understood the difference between them

In: Biology


Amnesia – you forget everything at once, but it wears off.
Alzheimer’s – you forget everything backwards. (You remember the past but not today.)
Dementia – you forget how to do things and the things around you don’t make sense.

This is an incredibly simplistic explanation of the three.

Dementia is an umbrella term for cognitive decline that is typically associated with age. There are numerous types of dementia, including Alzheimer Dementia.

Alzheimer disease is a specific disease that causes dementia.

Amnesia simply means a loss of memory. Like dementia, there are numerous types of amnesia. The most common one is alcohol induced amnesia, aka “blacking out”.

A very simplistic explanation:

Amnesia: memory loss caused by trauma (using this term very broadly), disease or drug use; can be temporary or permanent, can be loss of memories or inability to form new ones. It’s not just forgetting things, but more like whole chunks are gone.

Dementia: broad term for brain disorders that affects cognitive function (memory, thinking, problem-solving, etc) and is also a broad term for symptoms declining brain function. Dementia gets worse over time, although sometimes can be reversed.

Alzheimer’s: a form of dementia, an incurable disease.

Dementia involves more than one type of mental ability. For example, a person with dementia may have trouble with memory, planning, and language abilities. (One caveat: to qualify as dementia, a person must have their deficits while having “a clear sensorium.” That is, they can’t be drunk, stoned, or delirious.) Alzheimers disease is one type of dementia.

Amnesia refers specifically to a failure in memory.

Amnesia and some types of dementia can be permanent or temporary. Some examples of temporary causes of dementia are hypothyroidism and severe depression.