Dementia is not actually a disease. It is a group of symptoms. “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 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 correct. Although Alzheimer’s disease is the most common form of dementia, not everyone with dementia has Alzheimer’s:

  • Dementia is a brain disorder that impacts a person’s ability to communicate and 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.

The general 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
  • mood swings
  • confusion or disorientation in unfamiliar surroundings
  • paranoia
  • inability to multitask

Dementia can be categorized in many different ways. These categories are designed to group disorders that have particular features in common, such as whether or not they are progressive and which parts of the brain are affected.

Some types of dementia fit into more than one of these categories. For example, Alzheimer’s disease is considered to be both progressive and cortical dementia.

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

Lewy body dementia (LBD)

Lewy body dementia (LBD), also called dementia with Lewy bodies, 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.

The symptoms of LBD include:

  • visual hallucinations
  • slowed movement
  • dizziness
  • confusion
  • memory loss
  • apathy
  • depression

Cortical dementia

This term refers to a disease process that primarily affects the neurons of the brain’s outer layer (cortex). Cortical dementias tend to cause problems with:

  • memory
  • language
  • thinking
  • social behavior

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 when portions of the frontal and temporal lobes of the brain atrophy (shrink). Signs and symptoms of frontotemporal dementia include:

  • apathy
  • lack of inhibition
  • lack of judgement
  • loss of interpersonal skills
  • speech and language problems
  • muscle spasms
  • poor coordination
  • difficulty swallowing

Vascular dementia symptoms

Caused by brain damage from impaired blood flow to your brain, vascular dementia symptoms include:

  • trouble concentrating
  • confusion
  • memory loss
  • restlessness
  • apathy

Progressive dementia

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

  • Lewy body dementia
  • frontotemporal dementia
  • vascular dementia

Secondary dementia

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

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 area of the brain undergoing those changes. Examples of common mixed dementia include:

  • vascular dementia and Alzheimer’s disease
  • Lewy bodies and Parkinson’s disease dementia

Even for a given type of dementia, symptoms can vary from patient to patient.

Symptoms are usually progressive over time. For example, the symptoms associated with Alzheimer’s disease (AD) are often described in stages, or phases, representing 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 normal 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 and 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
  • inability to learn new things or to cope with new or unexpected situations
  • inappropriate outbursts of anger
  • perceptual-motor problems (such as trouble getting out of a chair or setting the table)
  • repetitive statements or movement, occasional muscle twitches
  • hallucinations, delusions, suspiciousness or paranoia, irritability
  • loss of impulse control (such as undressing at inappropriate times or places or using vulgar language)
  • exacerbation of 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 AD) can be seen in the brain when looked at using an imaging technique called MRI. This is the final stage of AD, and symptoms may include:

  • inability to recognize family and loved ones
  • loss of sense of self
  • inability to communicate in any way
  • loss of bladder and bowel control
  • weight loss
  • seizures
  • skin infections
  • increased sleeping
  • total dependence on others for care
  • difficulty swallowing

Not all people with dementia experience the same symptoms. The most common symptoms of dementia are difficulty with memory, communication, and cognitive abilities.

Different types of dementias have varied causes, and they 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 to your healthcare provider.

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