Dementia is a general term for symptoms that can affect memory, speech, and decision-making skills. These symptoms make it difficult to perform daily activities.

While sometimes thought of as a condition, dementia is not actually a disease. Dementia is a term for a group of symptoms that people may experience as a result of a number of conditions.

“Dementia” is a general term for behavioral changes and the loss of mental abilities.

This decline — including memory loss and difficulties with thinking and language — can be severe enough to disrupt your daily life.

Alzheimer’s disease is the best-known and most common type of dementia.

Many people use the terms “Alzheimer’s disease” and “dementia” interchangeably, but this isn’t medically correct. Although Alzheimer’s disease is the most common type of dementia, not everyone with dementia has Alzheimer’s:

  • Dementia is a group of symptoms that affect a person’s ability to think, remember, and make decisions. It can make it difficult to perform everyday activities.
  • Alzheimer’s disease is one form of dementia with a targeted impact on parts of the brain that control a person’s ability to think, remember, and communicate with language.

Learn more about the differences between Alzheimer’s and dementia.

Overall signs and symptoms of dementia include difficulty with:

  • memory
  • communication
  • language
  • focus
  • reasoning
  • visual perception

The early signs of dementia include:

  • loss of short-term memory
  • difficulty remembering specific words
  • losing things
  • forgetting names
  • problems performing familiar tasks such as cooking and driving
  • poor judgment
  • sudden mood changes
  • confusion or disorientation in unfamiliar surroundings
  • an inability to multitask

Dementia can be categorized in many different ways. These categories are designed to group conditions that have particular features in common, such as whether they’re progressive and which parts of the brain are affected.

Some types of dementia fit into more than one of these categories.

Here are some of the most commonly used groupings and their associated symptoms:

Lewy body dementia (LBD)

Lewy body dementia (LBD) is caused by protein deposits known as Lewy bodies. These deposits develop in nerve cells in the areas of the brain that are involved in memory, movement, and thinking.

This condition is also sometimes called dementia with Lewy bodies.

The symptoms of LBD include:

  • visual hallucinations
  • unpredictable changes in concentration, attention, alertness, and wakefulness
  • movement changes, such as parkinsonism (tremor or muscle stiffness)
  • sleep disorders, including rapid eye movement (REM) sleep behavior disorder
  • dizziness
  • confusion
  • memory loss
  • apathy (lack of emotion)
  • depression
  • poor regulation of body functions, such as blood pressure and body temperature

Subcortical dementia

This type of dementia affects parts of the brain below the cortex. Subcortical dementia tends to cause:

  • changes in emotions
  • changes in movement
  • slowness of thinking
  • difficulty starting activities

Frontotemporal dementia

Frontotemporal dementia occurs due to damage to nerve cells in the frontal and temporal lobes of the brain.

Signs and symptoms of frontotemporal dementia include:

  • changes in behavior or personality
  • apathy
  • lack of inhibition
  • lack of judgment
  • loss of interpersonal skills
  • socially inappropriate or impulsive behaviors
  • speech and language problems
  • poor coordination
  • difficulty swallowing

Vascular dementia

Vascular dementia is caused by brain damage from impaired blood flow to your brain. This may be due to a stroke or another condition that damages small blood vessels.

Symptoms may include:

  • trouble concentrating
  • confusion
  • memory loss
  • trouble speaking or understanding speech
  • apathy

Mixed dementia

Mixed dementia is a combination of two or more types of dementia. The symptoms of mixed dementia vary based on the types of changes to the brain and the areas of the brain undergoing those changes.

The most common type of mixed dementia involves the combination of Alzheimer’s disease and vascular dementia.

Progressive dementia

As the name implies, this is a type of dementia that gets worse over time. It gradually interferes with abilities like:

  • thinking
  • remembering
  • reasoning

Primary dementia

This is dementia that does not result from any other disease. This describes a number of dementias, including:

  • Alzheimer’s disease
  • Lewy body dementia
  • frontotemporal dementia
  • vascular dementia
  • mixed dementia

Secondary dementia

This is dementia that occurs as the result of a physical injury, such as head trauma, or diseases including:

Even within types of dementia, symptoms can vary from person to person. But symptoms typically progress over time.

For example, the symptoms associated with Alzheimer’s disease (AD) are often described in stages or phases. This represents the ongoing, degenerative nature of the disease.

Mild Alzheimer’s disease

In addition to memory loss, early clinical symptoms will likely include:

  • confusion about the location of usually familiar places
  • taking longer to accomplish usual daily tasks
  • trouble handling money and paying bills
  • poor judgment, leading to “bad” decisions
  • loss of spontaneity and sense of initiative
  • mood and personality changes or increased anxiety

Moderate Alzheimer’s disease

As the disease progresses, additional clinical symptoms may include:

  • increasing memory loss and confusion
  • shortened attention span
  • problems recognizing friends and family members
  • difficulty with language
  • problems with reading, writing, or working with numbers
  • difficulty organizing thoughts and thinking logically
  • an inability to learn new things or to cope with new or unexpected situations
  • inappropriate outbursts of anger
  • perceptual-motor problems, such as difficulty getting out of a chair or setting the table
  • repetitive statements or movement and occasional muscle twitches
  • hallucinations, delusions, or paranoia
  • irritability
  • loss of impulse control, such as undressing at inappropriate times or using vulgar language
  • exacerbated behavioral symptoms, such as restlessness, agitation, anxiety, tearfulness, and wandering — especially in the late afternoon or evening, which is called “sundowning”

Severe Alzheimer’s disease

At this point, plaques and tangles (the hallmarks of Alzheimer’s) can be seen in the brain when looked at using an imaging technique called MRI.

This is the final stage of Alzheimer’s, and symptoms may include:

While not all people with dementia have the same symptoms, the most common symptoms of dementia are difficulty with:

  • memory
  • communications
  • cognitive abilities

There are several types of dementia with varied causes. They all affect different mental, behavioral, and physical functions.

Alzheimer’s disease — the most common form of dementia — is progressive, with symptoms worsening over time.

If you or a loved one are experiencing problems with memory, difficulty performing familiar tasks, or mood or personality changes, talk with a healthcare professional.

Once you have an accurate diagnosis, you can explore options for treatment.