Differences between the 3 D's- Delirium, Dementia and Depression

Dementia, Delirium or Depresssion? annedde Collection: E+ /Gety Images.

There are three words that begin with the letter "D" - delirium, dementia and depression- that have multiple overlapping symptoms. However, distinguishing between them is essential for effective treatment and outcome.

What Are the Overlapping Symptoms?

Delirium, dementia and depression can all have a set of symptoms that involve cognitive impairment and emotional changes. The person might not interact appropriately with others, be listless and "down" emotionally, or have memory loss, feel confused, be disoriented and show poor judgment.

-Read more: What Does It Mean to Be "Oriented x3?"

How Can You Tell the 3 D's Apart?

Knowledge of the person's usual functioning is a must in order to distinguish between the three D's. There are a few different aspects that help tell delirium, dementia and depression apart. They include:

Onset- How quickly did the symptoms begin?

  • Delirium typically involves a more sudden change within the past few days or even hours.
  • Depression may trigger a more gradual decline over a period of weeks to months.
  • Dementia usually causes a very gradual change that can be seen if you compare the person's functioning to several months or a year ago.

Self-Awareness- Is the person aware of cognitive decline concerns?

  • In delirium, awareness varies, ranging from significant concern and awareness of confusion to a complete lack of awareness.
  • In depression, it's more common for the person to express some concern about his memory or a feeling of confusion. He may talk about the inability to keep everything straight in his mind.
  • People with dementia may be aware early on of memory struggles or difficulty making decisions, although they may attempt to hide their symptoms initially by deflecting or denying concerns. As the disease progresses, awareness of cognitive difficulty decreases.

Mood- What is the person's mood like most of the time?

  • In delirium, mood often varies widely from time to time.
  • Depression typically causes a consistent low mood and feelings of apathy.
  • In dementia, mood also tends to vary quite a bit. (Depression can also be present in addition to dementia, which can complicate diagnosis.)

-Read more: What Are some of the Subtle Early Signs of Dementia?

Are the 3 D's Treatable? 

Depression's symptoms can mimic the cognitive impairment of delirium and dementia. However, these symptoms may often resolve or decrease since the person's ability and desire to pay attention to what's going on around them should improve over time with appropriate and effective treatment.

-Read more: What Are Some Other Causes of Forgetfulness?

Delirium is an acute (sudden) condition- meaning that identification of the cause of delirium and treating that cause is very important. Often, infections such as a urinary tract infection or pneumonia can trigger delirium, but after treatment, cognitive functioning may be restored back (or near) to the person's baseline.

-Read more: How Do Infections Affect People with Dementia?

Dementia is a chronic, ongoing cause of cognitive impairment. While true dementia isn't curable, treatments such as medications and non-drug approaches can improve functioning and quality of life for a limited period of time. There is typically a general progression of symptoms over time.

-Read more: What Medications Treat Dementia?

-And this: Which Non-Drug Approaches Work in Dementia?

Complicating Factors

More than one of the three D's can exist at a time in the same person, and it's important that each is recognized and treated for the best possible outcome.

What Can You Do to Help a Loved One?

One important thing you can do is communicate to the physician whether these symptoms are very unusual for the person or whether they are quite typical.

For example, if your loved one needs to go to the emergency room, be sure to accompany her there and explain to the medical staff that her disorientation is significant and not normal for her so that delirium can be assessed.

Ask questions if you see a sudden increase of confusion or behavior change in someone who has dementia since they may have developed a treatable delirium in addition to the dementia.

Take note of signs of depression and be aware that someone with dementia may not always verbalize depression clearly. While someone with depression may be more tearful, depression in dementia can also trigger increased confusion or behavioral challenges.

-Read more: My Dad with Dementia Has to Go to the ER. How Can I Help Him?

-And this: Best Ways to Effectively Advocate for a Loved One

Helpful Resources:

AMA Journal of Ethics. Virtual Mentor. June 2008, Volume 10, Number 6: 383-388. Differentiating among Depression, Delirium, and Dementia in Elderly Patients.

Bosma, M. The 3 D's of Geriatric Psychiatry: Depression, Dementia and Delirium. Accessed February 24, 2015. http://novascotia.ca/dhw/mental-health/documents/seniors/3-d-of-geriatric-psychiatry.pdf

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