Understanding the Different Types of Dementia

When we hear the word dementia, many of us immediately think of Alzheimer’s disease. But dementia isn’t just one condition — it’s an umbrella term for a group of disorders that affect memory, thinking, and daily life. Understanding the different types is important for families because:

• Different dementias behave in different patterns
• Different dementias are treated differently
• Some dementias may be atypical and require specialist intervention
• Some “dementias” may not be dementias at all

Let’s take a look at the main types of dementia, their causes, key features, and what can be done to help.

1. Alzheimer’s Disease (AD)

What it is:
The most common cause of dementia. The one people think of when they think of “dementia.”

Cause:
Alzheimer's is actually a specific disease with a specific disease pattern. The disease is caused by abnormal buildup of proteins (amyloid plaques and tau tangles) in the brain over many years, disrupting nerve cells and disrupting communication between them.

Unique characteristics:

Gradual and progressive memory loss

Difficulty with language, problem-solving, and daily tasks

Later, changes in personality, judgment, and movement

Often starts with trouble remembering recent events

Diagnosed by:

Most often, Alzheimer's is still diagnosed clinically (that is, by your provider's best judgment following a set of established criteria). Actual testing for these specific proteins in the spinal fluid and even blood is emerging, and these will likely become more and more available in the coming years.

Treatment:

Medications such as donepezil, rivastigmine, galantamine, or memantine may help with symptoms

In select patients with early Alzheimer's, there are new therapies that target amyloid (lecanemab, donanemab). However they are infusion-based, involve significant commitment, and are not curative or highly effective. 

Medications for symptom management, such as depression or challenging behaviors.

Prognosis:
Usually progresses slowly over years. People can live 10-15 years (sometimes longer) after diagnosis with proper care and support.

2. Vascular Dementia

What it is:
Dementia caused by reduced blood flow to the brain — often after strokes or due to small vessel disease.

Cause:
Blocked or damaged blood vessels lead to brain cell injury or death.

Unique characteristics:

Often appears suddenly after a stroke, or gradually with ongoing vascular disease

The specific symptoms will depend on which areas of the brain are affected. However memory tends to be better than in Alzheimer's, while some other aspects like planning, problem-solving, and attention tend to be worse.

Diagnosis:
Clinical, but MRI/brain imaging findings will have specific importance.

Treatment:

Generally no cure for existing deficits. Treatment is aimed at preventing future strokes and optimizing against blood vessel disease.

Control risk factors: blood pressure, cholesterol, diabetes, and smoking.

Blood thinners when appropriate.

Prognosis:
Progression depends on underlying vascular health — can be stepwise or gradual. 

3. Lewy Body Dementia (LBD)

What it is:
A somewhat common dementia related to abnormal protein deposits called Lewy bodies.

Cause:
A buildup of alpha-synuclein protein in brain cells that affects movement, thinking, and behavior. This is the same protein that is involved in Parkinson's disease. (This is essentially the same thing as Parkinson's disease dementia, the only difference being which symptoms show first).  

Unique characteristics:

Fluctuating alertness or attention (“good days and bad days”)

Visual hallucinations (seeing things that aren’t there)

Delusions, agitation, and other significant behavioral changes

Parkinson-like movement problems (stiffness, shuffling walk)

REM sleep behavior disorder (acting out dreams)

Blood pressure drops while standing, constipation

Diagnosis:

Still mostly clinically. However Lewy bodies accumulate everywhere in the body, not just the brain, so LBD actually can be diagnosed with a skin biopsy, which is becoming more common. 

Treatment:

Some Alzheimer’s medications can help with memory and alertness.

Parkinson’s medications may help with movement but can worsen hallucinations.

Medications for symptom management, though some of these may be different than in other dementias.

Prognosis:
Progresses gradually. People may live 5–10 years after diagnosis.

4. Frontotemporal Dementia (FTD)

What it is:
A group of disorders affecting the brain’s frontal and temporal lobes — areas that control behavior, personality, and language.

Cause:
Abnormal protein buildup (tau or TDP-43) leading to nerve cell damage.

Unique characteristics:

Personality and behavior changes early on (disinhibition, apathy, loss of empathy)

Language problems (trouble speaking or understanding words)

Memory may remain relatively intact in early stages

Often appears earlier in life than other dementias (ages 45–65)

Diagnosis:

Clinical.

Treatment:

No cure, but medications may help with mood or behavioral symptoms.

Speech, occupational, and behavioral therapy

Prognosis:
They're generally progressive. Life expectancy depends on specific subtype of FTP. Some can be as long as 10+ years, though some are shorter.

5. Mixed Dementia

What it is:
A combination of two or more types of dementia, most often Alzheimer’s and vascular dementia, or Alzheimer’s with Lewy body disease. Mixed dementia is thought to be the most common dementia. 

Treatment:
Treating the individual dementias. Most mixed dementias will have an Alzheimer's component, so Alzheimer's treatments are usually involved. 

6. Other and Rarer Dementias

These include:

Parkinson’s disease dementia – occurs in people with longstanding Parkinson’s, see section on Lewy body dementia.

Huntington’s disease – inherited disorder affecting movement and thinking.

Creutzfeldt-Jakob disease – rare, rapidly progressing brain disease caused by abnormal prion proteins.

7. Reversible Causes of Dementia-like Symptoms

Not all memory loss means dementia! Some conditions can mimic it — and are treatable. This is why the initial evaluation of dementia usually involves clinical assessment, blood testing and brain imaging. These conditions include:

Vitamin B12 deficiency

Thyroid problems

Normal pressure hydrocephalus (fluid buildup in the brain)

Alcohol-related brain injury

Infections (such as HIV, syphilis) or metabolic disorders

Depression or anxiety

Medication side effect or interaction

Treatment:
Addressing the underlying cause can significantly improve thinking and functioning.

When does a neurologist need to be involved in dementia?

● When the age of onset of dementia is younger than expected (age <65)

● When there are rapidly progressing symptoms, over weeks to months instead of years

● When the clinical picture is not usual for dementia, or when the medical history is very complex

● When there are concurrent concerning neurological symptoms present (such as balance, tremors, rigidity, or unusual muscle weakness)

● When a second opinion or clarification of a diagnosis is requested by family

● Lewy body dementia, frontotemporal dementia, and the less common dementias will also usually have a neurologist involved