The Most Common Types of Dementia

January 31, 2016 Information about dementia

The term “dementia” is often used to describe any disease that affects a person’s memory or mental abilities, but in fact there are several distinct types of dementia, each with different characteristics.

In 2013 the American Psychiatric Association published the latest edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), which among other things, provides the diagnostic criteria for different types of demen tia. It is used to diagnose and classify mental disorders, including dementia, by the medical community in much of the world.

According to the new Manual, a diagnosis of dementia requires that there be evidence of a significant cognitive decline from the previous level of function in at least one cognitive domain (see our article "Dementia Cognitive Domains") and the decline must be severe enough to interfere with the person’s activities of daily living.

COGNITIVE DOMAINS

A diagnosis of dementia requires significant decline in at least one of these cognitive domains:

Complex attention
Executive function
Learning and Memory
Language
Perceptual-motor
Social cognition

More information at "Dementia Cognitive Domains"

A person experiencing a loss of function that does not impair daily living is considered to have mild cognitive impairment, or MCI (see our article "Mild Cognitive Impairment"), rather than dementia.

While there are many more types of dementia, Alzheimer’s Disease, Vascular Dementia, Lewy Body Dementia and Frontotemporal Dementia make up some 80 to 90 percent of all cases. It is important to identify the type of dementia (or dementias because a person can have more than one type) that a person has because it affects their treatment and care options.

Here is a brief description of each of the four major types of dementia and some of their symptoms.

ALZHEIMER’S DISEASE (AD)

The commonest type of dementia (70% to 80% of all cases) characterized by memory loss, confusion, difficulty communicating, paranoia and anxiousness.

Progression

Onset of the disease is “insidious”, meaning that it is so gradual that it is well established before becoming apparent.
The disease progresses gradually.

Alzheimer's Symptoms Dementia

Memory loss and impaired learning ability early in the disease
Language and visuospatial (the ability to perceive objects and the spatial relationship between them) deficits in mid to late stages

Possible Features of Alzheimer's Dementia

Depression and apathy in early stages
Agitation, wandering in mid to late stages
Gait issues, difficulty swallowing, seizures

Other

Often occurs with vascular dementia

VASCULAR DEMENTIA (VAD)

The second most common form of dementia, vascular dementia is also known as “multi-infarct dementia” or “post-stroke dementia” because it is caused by bleeding within the brain. It is characterized by impaired judgement, loss of the ability to plan and loss of motivation.

Progression

Onset can vary depending on location of blood flow disruption but is often sudden.
Decline is often in steps

Symptoms

Loss in executive and complex attention domains, memory loss is secondary and is sometimes spared

Possible Features

Personality and mood changes
Parkinson-like symptoms but insufficient for Parkinson’s diagnosis
Slow, gradual progression due to small vessel disease
Depression

Other

Often occurs along with Alzheimer’s Disease and/or Lewy Body Dementia

LEWY BODY DEMENTIA DISEASE (DLB)

Caused by the presence of abnormal Lewy body proteins in nerve cells, Lewy Dementia Disease is the third most common type of dementia. It is characterized by sleep problems, hallucinations, memory loss and frequent changes in alertness.

Progression

Onset is “insidious”, meaning that it is so gradual that it is well established before becoming apparent.
The disease progresses gradually.

Symptoms

Early changes in complex attention and executive domains
Recurrent, detailed hallucinations early in the disease
Spontaneous Parkinson-like symptoms shortly after, or concurrent with cognitive symptoms

Possible Features

REM sleep disorder can be an early sign
Severe sensitivity to antipsychotic drugs (neuroleptics)
Falls and sudden loss of consciousness
Problems with the autonomic nervous system (which controls blood pressure, heart rate, etc.)

Other

Frequently occurs with Alzheimer’s Disease and/or Vascular Dementia

FRONTOTEMPORAL DEMENTIA (FTD)

Much less common, but thought to be the fourth most prevalent type of dementia, frontotemporal dementia has more behavioral, emotional and language symptoms than memory and learning losses. In fact, memory is often spared in this type of dementia. There are several forms of the disease (behavioral and language being the most common), but they are all caused by atrophy or shrinking of the frontotemporal lobes. It is often misdiagnosed as Alzheimer's Disease or a psychiatric problem.

Progression

Onset is “insidious”, meaning that it is so gradual that it is well established before becoming apparent.
The disease progresses gradually.

Symptoms

Two variants of the disease, both are often present:

Behavioral variant

Changes in social cognition, language and/or executive domains
Behavioral symptoms including disinhibition, lack of empathy, apathy, compulsive behavior and eating inappropriate objects

Language variant