Dementia or Alzheimer’s? Key Differences for Families and Caregivers
People often use the words dementia and Alzheimer’s disease interchangeably, but medically they describe two different concepts. Dementia is a syndrome, where a cluster of symptoms tend to appear together. Alzheimer’s disease is a specific illness that can cause that syndrome.
While a disease has a defined cause, a syndrome may produce several symptoms without a single identifiable source. The word itself comes from the Greek phrase meaning “run together,” which captures the idea that multiple symptoms converge into one recognizable pattern.
How dementia is defined
The DSM‑5, a major diagnostic reference for psychiatric and neurologic conditions, defines dementia using four criteria:
- The person has chronic and progressive cognitive impairment.
- The cognitive impairment is not acute, and it has lasted more than six weeks.
- The cognitive impairment is severe enough to cause functional problems, such as difficulty working, maintaining a household, planning, organizing, or managing daily responsibilities. Memory loss is often the first noticeable sign.
- The cognitive impairment is not caused by a potentially reversible condition, such as depression, thyroid disease, or vitamin B12 deficiency.
All of these criteria above may sound clinical, but for most families, the journey begins with a simple worry. Maybe you’ve noticed your loved one asking the same question again and again, getting lost in familiar places, or struggling to keep up with conversations. These are important signs. If you spot them, sharing your observations with a doctor can be a crucial first step. Doctors use simple cognitive tests (sometimes called “instruments”) that measure memory, attention, language, and problem‑solving to clarify what’s happening and guide you toward the right support.
Once cognitive impairment is documented, the next step is to search for potentially reversible causes. This includes checking for vitamin B12 deficiency, thyroid disease, depression, or even signs of a stroke. Only after reversible causes are ruled out does the clinician move on to determine the stage of dementia and cause of the impairment.
How dementia is staged
Patients are staged using standard criteria that reflect both the degree of cognitive impairment and the level of functional impairment. The progression typically begins with Mild Cognitive Impairment (MCI), in which cognitive changes are noticeable, but functional abilities remain largely intact.
As the condition advances, individuals may enter the stage of mild dementia, followed by moderate dementia, and eventually severe dementia. These stages provide a framework for guiding treatment decisions, planning care, and anticipating how the condition may progress over time.
Common causes of dementia
Many conditions can lead to dementia. The most common include Alzheimer’s disease (AD), Lewy Body disease (LBD), cerebrovascular disease, Frontotemporal degeneration (FTD), and normal pressure hydrocephalus (NPH).
Although these diseases differ in their underlying pathology and causes, they usually share early symptoms such as memory loss, while also presenting features unique to each condition. For example, a loved one with Alzheimer’s may have increasing trouble remembering recent events, while someone with Frontotemporal Degeneration might show personality changes first.
Reflecting on which symptoms appear can help families share helpful details with doctors and get the right diagnosis.
Alzheimer’s Disease and Frontotemporal Dementia
As discussed above, dementia is a syndrome with multiple possible causes. Two of those causes, Alzheimer’s disease and Frontotemporal Degeneration (FTD), can begin with memory loss, but FTD typically presents early changes in personality and executive function. This affects the brain’s abilities to plan, organize, and multitask. While the symptoms may look different at first, both conditions eventually progress from moderate to severe dementia.
At advanced stages, patients typically lose the ability to do many things most of us take for granted, such as:
- Toilet independently
- Control bladder or bowel function
- Eat without assistance
- Choose appropriate clothing or dress themselves
- Walk safely without help
- Bathe or shower independently
Behavioral disturbances, including agitation and psychosis, are common and often make caregiving extremely challenging.
Why treatment differs between Alzheimer’s and FTD
New disease‑modifying drugs approved by the FDA for Alzheimer’s disease target amyloid plaques, which are a hallmark of AD. These plaques do not exist in FTD, meaning the same medications do not help FTD patients. Today, blood tests and neuroimaging can diagnose Alzheimer’s disease by detecting amyloids and determining whether a patient is eligible for these new treatments, which remove amyloids from the brain and slow disease progression. These drugs do not work in FTD because the underlying pathology is different.
Lewy Body Dementia
Lewy Body dementia follows a similar model of causation. The defining feature seen at autopsy is the presence of Lewy bodies, deposits of a protein called alpha‑synuclein. Diagnostic tests that detect alpha‑synuclein in spinal fluid are currently in development for patients suspected of having LBD based on clinical features.
If you’re wondering what to look for, early signs of LBD include:
- Fluctuations in alertness and cognition, sometimes within hours
- Periods of clarity alternating with confusion or unresponsiveness, even within the same day
- Visual hallucinations, such as seeing people, animals, or shapes that aren’t there
- Thinking problems, including difficulty with multitasking, planning, judgment, and problem‑solving
- Mood disturbances, such as depression, anxiety, apathy, or agitation
- Parkinsonian symptoms, including slowed movement, stiffness, and tremors
- REM sleep behavior disorder, in which patients physically act out their dreams
Patients with LBD often respond better to cholinesterase inhibitors than those with Alzheimer’s disease. However, when LBD patients experience psychosis or agitation, antipsychotic medications, which are commonly used in dementia care, can cause more frequent and severe side effects because LBD patients tend to have baseline Parkinsonian features.
Managing behavioral symptoms in LBD can be challenging for both physicians and caregivers. It should be noted that about 20% of patients with Parkinson’s disease develop Lewy Body dementia, usually late in the course of the illness.
Mixed dementia
Approximately 40% of patients have “mixed dementia,” meaning that pathology, or evolving blood and spinal fluid testing, shows evidence of both amyloid plaques and Lewy bodies. This overlap reinforces the idea that caring for patients with dementia, regardless of cause, generally follows similar principles, especially regarding behavioral management as patients move through the seven stages of dementia.
Vascular dementia
Vascular cognitive impairment, or vascular dementia, is diagnosed when a patient shows evidence of underlying vascular disease. This may include conditions such as coronary artery disease, carotid artery disease, or characteristic findings on brain MRI, such as microinfarcts or white‑matter microvascular changes.
Most individuals with vascular dementia begin to show early difficulties with both memory and executive functioning. While caring for someone with vascular dementia is similar to managing other types, there’s a crucial difference: controlling heart and blood vessel health is the top priority.
Families can make a real difference by helping loved ones attend regular checkups, manage blood pressure, diabetes, and cholesterol, encourage healthy eating, and stay active as much as possible. Small steps, like going for short walks together or preparing nutritious meals, can have a big impact on slowing the disease’s progression and improving quality of life.
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