Dementia is the syndrome. Alzheimer's is its most common cause.
The two terms are often used interchangeably, but they do not mean the same thing. Understanding the difference makes the rest of brain-health information much easier to interpret.
Dementia is an umbrella term for cognitive decline severe enough to interfere with daily life. Alzheimer's disease is a specific disease defined by characteristic amyloid and tau pathology and accounts for approximately 60-70% of dementia cases.
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The difference in one paragraph
Dementia describes a set of symptoms, including decline in memory, reasoning, language, or judgment that impairs daily functioning. Alzheimer's disease is one specific cause of dementia.
A useful analogy is that dementia is a syndrome, while Alzheimer's is a diagnosis that can produce that syndrome. So everyone with Alzheimer's dementia has dementia, but not everyone with dementia has Alzheimer's disease.
The main types of dementia
Alzheimer's disease. The most common cause. It is associated with amyloid plaques and tau tangles and often begins with memory problems, though each person's experience is slightly different.
Vascular dementia. Caused by damage to the brain's blood supply. Symptoms can include slowed thinking, impaired planning, and changes related to strokes or small-vessel disease.
Lewy body dementia. Associated with abnormal alpha-synuclein deposits. It can involve visual hallucinations, fluctuating attention, sleep changes, and movement symptoms.
Frontotemporal dementia. A group of diseases affecting the frontal and temporal lobes. It often begins with personality, behavior, or language changes and can occur at younger ages.
Mixed pathology is also common, especially Alzheimer's plus vascular disease.
The diagnosis matters for treatment.
Despite the differences, it's thought that many of the modifiable risk factors for these dementias overlap. This includes blood pressure, lipids, blood sugar, physical activity, hearing, sleep, and smoking.
That overlap is where BetterBrain focuses.
How common dementia is
An estimated 57 million people worldwide were living with dementia in 2021, and age is the largest risk factor. In the United States, an estimated 7.4 million people age 65 and older are living with Alzheimer's dementia. Dementia is not a normal part of aging, even though risk rises substantially with age.
What causes it
Each dementia type has different biology, but many risk factors overlap. The 2024 Lancet Commission links nearly half of dementia cases to 14 modifiable risk factors, including hearing loss, high LDL cholesterol, hypertension, diabetes, physical inactivity, smoking, depression, excess alcohol, obesity, social isolation, and vision loss.
Vascular health matters directly for vascular dementia and also appears to influence Alzheimer's risk.
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Dementia may feel like a purely neurological topic, but some of the most common preventative opportunities BetterBrain sees are cardiovascular and metabolic. In BetterBrain's client population, 47% have so far returned with a suboptimal ApoB, with 22% having an ApoB level high enough to be directly linked to an increased risk of dementia. This makes ApoB one of the most commonly out-of-range markers the company reports seeing.
That is not a prevalence estimate for the general public, just the BetterBrain client data. But it illustrates why the distinction between Alzheimer's and vascular dementia does not make vascular health irrelevant to Alzheimer's prevention. Healthy blood vessels matter to every brain.
What the evidence says
Amnesia is not the same as dementia. Amnesia refers specifically to memory loss. Dementia involves broader cognitive decline and impairment in daily function.
The exact diagnosis matters for care. Different dementia types can require different treatment and management. But many of the risk factors associated with long-term brain health are shared.
Why the distinction matters for prevention
The label matters clinically. The modifiable factors often overlap. That means the person reading about a parent's diagnosis can still ask a useful question about themselves: How are my blood pressure, lipids, blood sugar, hearing, activity, sleep, and other risk factors?
BetterBrain focuses on that earlier window, before diagnosis, when the goal is to understand risk and improve the factors that can still be changed.
Common questions
What is the difference between dementia and Alzheimer's?
Dementia is a clinical umbrella term for cognitive decline that interferes with daily life. Alzheimer's is a specific disease and the most common cause of dementia.
How common is dementia?
Tens of millions of people worldwide live with dementia. Risk rises sharply with age, but dementia is not a normal or inevitable part of aging.
What is the difference between vascular dementia and Alzheimer's?
Alzheimer's is defined by characteristic amyloid and tau pathology. Vascular dementia results from damage to the brain's blood supply. Mixed cases are common, and most people with Alzheimer's disease also have evidence of vascular disease.
Is dementia a normal part of aging?
No. Aging can include slower recall or occasional forgetfulness that doesn't meaningfully impact you on a daily basis. Dementia involves a level of decline that interferes with everyday function.
The diagnosis comes later. Many of the factors that shape brain health are visible earlier.
If you are reading this because someone in your family has dementia, their diagnosis matters for their care. For your own future, the more useful question is which of your risk factors you can identify and improve now.