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What’s the difference between delirium and dementia?

Both conditions are certainly frightening. Patients get suddenly thrown into confusion – or faced with a slow, inevitable decline. Meanwhile, friends and family of the patient see their loved one either suddenly turn into a confused, panicking stranger or deal with watching someone’s personality and memory be erased.

The words “dementia” and “delirium” are often used interchangeably. That’s a mistake – they’re separate conditions.

The major differences

According to Mayo Clinic, distinguishing the two conditions from each other can be difficult. Some patients can have both disorders; people with dementia frequently experience periods of delirium. There are three distinct areas the two disorders differ:

  • Changing symptoms: Although the relative functioning of people with dementia can change throughout the day, memory and other cognitive skills stay roughly consistent. In patients with delirium, their symptoms change radically and often.
  • Mental focus: Patients in the early stages of dementia are still fairly alert to their surroundings. Patients with delirium have a significant inability to maintain focus and awareness of their surroundings.
  • Onset: Delirium occurs quickly; dementia begins with symptoms that gradually get worse over a long period of time

What is delirium?

Also known as “acute confusional state,” Mayo Clinic defines delirium as a serious disturbance of one’s mental functioning, resulting in confusion, a reduction of cognitive skills and reduced awareness of one’s surroundings. The condition can also affect a person’s memory, especially short-term memory. Delirium’s onset can range from a matter of hours to several days. The condition can be caused by a variety of reasons, including:

  • Alcohol or drug abuse – or withdrawal
  • Chronic or severe illness
  • Complications from surgery or medications
  • Metabolic changes, such as low sodium

Mayo Clinic states there are three kinds of delirium:

  • Hyperactive delirium: The easiest type of delirium to recognize, this form of delirium caused patients to become agitated and restless and experience rapid changes in mood. Some patients even hallucinate.
  • Hypoactive delirium: This is the exact opposite of hyperactive delirium. Patients with this form of delirium are often dazed and sluggish.
  • Mixed: This form of delirium includes both hyper- and hypoactive symptoms. Patients can switch between the two states rapidly.

What is dementia?

The Alzheimer’s Association (AA) calls dementia a “general term for a decline in mental ability severe enough to interfere with daily life.” Dementia’s symptoms can vary greatly among people, which can make diagnosis difficult. According to AA, in order to define dementia, a patient must have significant impairment in two of the five cognitive areas:

  • Focus and attention
  • Judgment and reason
  • Language
  • Memory
  • Sight and perception

Alzheimer’s disease is the most common form of dementia – AA estimates it makes up 60 to 80 percent of dementia cases. Vascular dementia, a type of dementia caused by reduced blood flow to the brain, often occurs from stroke. Another common form of dementia is Dementia with Lewy Bodies (DLB). This form of dementia is caused by the build-up of proteins in areas of the brain which control memory and movement.

However, a lesser-known type of dementia has recently entered the public’s consciousness.

Chronic traumatic encephalopathy

Although chronic traumatic encephalopathy (CTE) has been in the public spotlight due in part to the recent movie “Concussion,” according to Boston University’s CTE Center it’s been recognized since the 1920s, when it was known to affect boxers, giving it the names “punch drunk syndrome” or “dementia pugilistica.” BU’s researchers believe CTE is caused by repeated trauma to the brain, either via concussions or less-severe hits that do not cause the symptoms of concussions.

AA adds that CTE seems to be related to the buildup of tau protein in the brain, which is also a sign of Alzheimer’s. It’s worth noting AA reports there is no evidence a single concussion increases the risk of developing CTE; rather, CTE seems to develop some years after receiving a large number of traumatic brain injuries.

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About the author

Brian Moore is a staff writer and graphic designer for the Sovereign Health Group. A 20-year veteran of the newspaper industry, he writes articles and creates graphics across Sovereign’s portfolio of marketing and content products. Brian enjoys music, bicycling and playing the tuba, which’s he’s done with varying degrees of success for over 25 years. For more information and other inquiries about this media, contact the author and designer at

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