The difference between Alzheimer's disease and other dementias

Overview

While the terms "Alzheimer's disease" and "dementia" are often used interchangeably, it's important to know the difference between the two.

• Dementia is not one specific disease. Rather, it's an umbrella term for a set of symptoms caused by physical disorders affecting the brain.
• Alzheimer's disease is the most common cause for dementia, accounting for 60-80% of all diagnoses.

Overall, know that Alzheimer's disease is a specific disease, while dementia is a general term for a group of similar diseases, of which Alzheimer's is one.

In other words, every case of Alzheimer's disease is an example of dementia, but not every type of dementia is Alzheimer's.

Symptoms

The symptoms of dementia include:

• Memory loss, both short-term and long-term,
• Difficulties with thinking, problem-solving or language that are severe enough to reduce a person's ability to perform everyday activities, and
• Changes in mood or behaviour.

The symptoms for Alzheimer's disease mostly overlap with other types of dementia, but there can be some differences.

For example:

Other dementias can focus more on certain symptoms, and less on others. In the case of frontotemporal dementia, changes in personality are more apparent in the early stage, while memory decline often doesn't arise until the later stage.

Affected areas of the brain

The differences in symptoms can be explained by the area of the brain each type of dementia affects.

For example:

While Alzheimer's disease generally affects most of the brain, frontotemporal dementia primarily affects the frontal and temporal lobes of the brain – the areas generally associated with personality and behaviour.

This explains why changes in personality are usually more obvious in the early stage of frontotemporal dementia than in the early stage of Alzheimer's.

Risk factors

Risk factors between different types of dementia also overlap, but there are some types that are more determined by a certain risk factor than others.

For example:

Stroke is now understood to be a common cause of vascular dementia. When a stroke occurs and the brain’s blood supply is blocked or damaged, brain cells are deprived of oxygen and die, leading to dementia. Because of that, having a stroke increases the risk of getting vascular dementia.

Genetics are a pronounced risk factor for Creutzfeldt-Jakob disease, one of the rarest types of dementia. If a parent has a mutation in their human prion protein gene, the chances that they will pass down Creutzfeldt-Jakob disease is 50% for each child.

Treatments

Because of the differences in symptoms, affected areas of the brain and possible causes, a treatment that works for one type of dementia may not be effective for another type.

For example:

While there are four medications available that can fight the symptoms of Alzheimer's disease, there are no known treatments to slow the progression of Creutzfeldt-Jakob disease.

Video source: What’s the difference between Alzheimer’s Disease and dementia? FreeDem Films, 2013. This video was created by Dr. Sabina Brennan of Trinity College Dublin and Trinity Brain Health. Permission to use this video was granted by Trinity Brain Health, which reserves all rights.