As discussed by the National Institute of Neurological Disorders and Stroke (NINDS) of the National Institutes of Health (NIH), dementia can be categorized in many different ways. These categories are designed to group disorders that have particular features in common, such as whether they are progressive and what parts of the brain are affected.

However, some types of dementia fit into more than one of these categories, e.g., Alzheimer’s disease is considered both a progressive and a cortical dementia. Here are some of the most commonly used groupings and their associated symptoms:

Cortical Dementia

This term refers to a disease process that primarily affects the brain's cortex (the outer layer)—which is full of neurons (brain cells). Cortical dementias tend to cause problems with memory, language, thinking, and social behavior.

Subcortical Dementia

This dementia affects parts of the brain below the cortex. Subcortical dementia tends to cause changes in emotions and movement, in addition to problems with memory.

Progressive Dementia

As the name implies, this is dementia that gets worse over time, gradually interfering with more and more cognitive abilities (such as a loss of thinking, remembering, and reasoning skills).

Primary Dementia

This is dementia that does not result from any other disease.

Secondary Dementia

This is dementia that occurs as a result of a physical disease or injury (most commonly a head injury)

Additionally, even within a given diagnosis of dementia, there is variation as to which, when, if—and to what extent—any given symptoms may become apparent. For example, the symptoms associated with Alzheimer’s disease (AD) are usually categorized as follows:

Mild AD

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 AD

As the disease spreads to more regions of the brain, 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, called, “sundowning”

Severe AD

At this point, plaques and tangles (the hallmarks of AD) can be seen in the brain when looked at by an imaging technology known as MRI. This is the final stage of AD. These symptoms may include:

  • inability to recognize family and loved ones
  • sense of self seems to entirely vanish
  • unable to communicate in any way
  • lack of bladder and bowel control
  • weight loss
  • seizures
  • skin infections
  • groaning, moaning, or grunting
  • increased sleeping
  • totally dependent on others for their care
  • difficulty swallowing