What Is the Difference Between Alzheimer’s and Dementia?

This article is part of our series on dementia and cognitive impairment. 

1. What Are the Forms of Dementia and Why Is It Important to Make a Distinction?
2. How is Dementia Diagnosed?
   

Although the words "Alzheimer's" and "dementia" are often used interchangeably, they are not synonymous. Here are the key differences.

Both Alzheimer's and dementia refer to a decline in brain functions. Both also often occur with aging. In most cases, both Alzheimer's and dementia are manifested by a significant loss of memory.

However, it is important to recognize that Alzheimer's does not mean dementia, and vice versa. What's the difference? Alzheimer's disease is one of the many forms of dementia.

Alzheimer's Is a Kind of Dementia, but What Exactly Is Dementia?

Dementia refers to the diseases that diminish the functions of the brain (also called cognitive functions). As normal aging is generally accompanied by cognitive changes, it is the degree of impact and the functions impacted that distinguish normal aging from dementia.

Indeed, even as our brain ages alongside our body, normal aging should not prevent us from carrying out the activities and tasks required daily (like managing our finances, cooking, or driving). It is only when the decline in cognitive functions (memory, among others) leads to significant difficulties in daily functioning that we speak of dementia. By definition, a person living with dementia must therefore have difficulty performing their daily tasks.

Dementia becomes more common with age, and up to one in three people over the age of 85 may be affected. More recently, dementia has also been referred to as "major neurocognitive disorder." Of all forms of dementia, Alzheimer's disease is the most common.

The Main Causes of Dementia

We distinguish the forms of dementia by their mechanisms of attack on the brain and by their consequences on its functioning. The main types of dementia are:

• Alzheimer's disease
• Vascular dementia (attacking the blood vessels of the brain)
• Mixed dementia (attack of blood vessels and Alzheimer's)
• Lewy Body Dementia
• Dementia associated with Parkinson's disease
• Frontotemporal dementia (of which there are behavioural and language variants)

All these forms of dementia are sometimes classified into two families: neurodegenerative and non-neurodegenerative. The neurodegenerative causes are those in which the mechanism of dementia derives directly from the degeneration, then death, of the main cells of the brain: the neurons. In the list above, all forms of dementia are neurodegenerative, except for vascular dementia.

The figure below illustrates the main forms of dementia and indicates which are neurodegenerative.

There are several forms of dementia — here are the main ones and how they are categorized.

To Learn More

• To better understand the different types of dementia, read our article: What Are the Forms of Dementia and Why It Is Important to Make a Distinction?
• To learn how memory problems and cognitive impairment are assessed, read our article: How is Dementia Diagnosed?
• To understand the stages of Alzheimer's disease, read our article: The Evolution of Alzheimer's Disease: What to Expect