What is the Difference Between Alzheimer's and Dementia?We recently received this question from a commenter:

What is the difference between Alzheimer’s and dementia?

That is a great question, and one that many people ask, so I thought I would tackle it here.

When we talk about dementia, we are talking about symptoms. The term “dementia” describes a set of symptoms that includes things like memory loss, trouble behaving appropriately in social situations, difficulty speaking or understanding language, and so forth. If a doctor says that a patient has dementia, what the doctor means is that the patient is showing some of these symptoms.

Dementia has many different causes, and Alzheimer’s disease is one cause of dementia. Using a variety of tests, like blood tests, psychological test, brain scans, and so forth, doctors can home in on what may be causing dementia in a particular patient. Sometimes, the answer is that Alzheimer’s is causing the dementia.

Alzheimer’s disease is responsible for around two-thirds of all dementia cases. But there are many other causes of dementia as well. The second most common cause, after Alzheimer’s, is called Lewy body dementia. Parkinson’s disease is another cause. Having a stroke can cause vascular dementia–a dementia that is a result of a lack of blood flow to the brain. Of course because the brain is complex, it’s rare that a person has strictly one cause of dementia with no overlap; for example, Lewy body dementia often overlaps with Alzheimer’s disease and/or Parkinson’s disease.

There are many other, more rare causes of dementia as well, like Huntington’s disease, which is genetically inherited, as well as dementia caused by repetitive brain injury, like you might find in a boxer or football player. Even rarer, dementia can also occur because of Creutzfeldt-Jakob disease (“Mad Cow”.)

Some types of dementias are temporary and reversible. These include dementias caused by poor nutrition, a reaction to a medication, infection, poisoning, tumors, or brain bleeds. Generally once the thing causing the dementia is gone, the patient can recover normally without symptoms.