Dementia and Delirium: 5 Key Differences

You visit Dad in the hospital, and he asks you why he’s in a flower garden. You’re trying to talk to Mom, but she can’t follow the flow of conversation. If your parent is over sixty-five, you may wonder if you’re seeing the onset of Alzheimer’s or some other form of dementia.

However, that’s unlikely. Dementia progresses slowly. If you see a sudden change in an older person’s mental or emotional state, it’s more likely to be delirium.

It’s important to know the difference: dementia is a chronic condition. Delirium, however, is a medical emergency.

What’s the difference between dementia and delirium? Here 5 ways to tell:

1. Onset

Dementia begins slowly, usually with memory loss. It generally takes time to recognize a pattern to the loss of function.

Delirium has a sudden onset. Someone with delirium might be functioning properly one moment, and then suddenly start hallucinating.

2. Duration

Dementia is a chronic disease. In most cases, it is incurable, although if brought on by other conditions, it may be reversed. Dementia is also progressive, meaning that cognitive function will continue to degrade.

Delirium is an acute state; its onset is abrupt, and its duration is short — assuming proper treatment is received. Without prompt and proper treatment, it can have severe repercussions.

3. Causation

Dementia is usually caused by a neurodegenerative disease: a disease that causes the death of brain cells.
It can also be caused by other insults to the brain, such as a stroke, a tumor, or a head injury.

Delirium is usually triggered by some other acute cause.
This cause may be an infection, such as a urinary tract infection or pneumonia.
Particularly in the elderly, the cause may be a relatively minor medical issue, such as constipation, dehydration, or sleep deprivation.
A change in environment, particularly a move into an environment that is completely unfamiliar, such as a hospital, is such a common cause of delirium in older people that it even has its own name: hospital- or ICU-psychosis.
Medication interactions, as well as illicit drug use or withdrawal from alcohol or illicit drugs, can also cause delirium.

4. Symptoms

Dementia is marked by loss of memory, and memory loss is also the first symptom to appear.
Finding the right words becomes increasingly difficult, and the person may start to have difficulty completing everyday tasks, such as cooking.
A person with dementia may become easily lost, even in familiar environments; and may start misplacing common items, such as their keys.
As the disease progresses, the symptoms worsen; communication and abstract thinking become difficult or impossible, and the person may develop changes in personality and mood.

Delirium, on the other hand, does not generally involve any memory issues.
Instead, the personality and mood changes common in late-stage dementia appear abruptly.
The person may be unable to speak coherently; they may hallucinate; and they may become either hyperactive or unresponsive.

5. Treatment

Dementia has no cure, but there are many treatments to slow the progression of symptoms.

Delirium, if caused by an infection or other illness, will resolve when that illness is addressed.
The most important issue with delirium is that it be identified as soon as possible, so that it can be treated.
Untreated, it not only causes significant distress to the person and their loved ones, but can also lead to other complications, including dementia or even death.


At Beacon of LIFE in Oceanport, NJ, our caregivers are so familiar with our clients that they readily note behavioral changes. Our staff, from our physicians to our dietitians, create every resident’s personalized plan with an eye toward maintaining optimal physical and mental health.

Beacon of LIFE is a government-approved PACE program created to provide seniors, their family, caregivers and professional health care providers the flexibility to meet their health care needs while continuing to live in their community.

Beacon of LIFE maintains an interdisciplinary team of professionals who give each client the coordinated care they need. Our staff specialize in working with older people, and work with each client and their family to develop the most effective plan of care.

We provide a variety of services, including primary care, hospital care, medical specialty services, prescription drugs, nursing home care, emergency services, home care, physical therapy, occupational therapy, adult day care, recreational therapy, meals, dentistry, nutritional counseling, social services, laboratory / X-ray services, social work counseling, and transportation.

Our care and services allow people who would otherwise need to live in a nursing home to live where they want — in their own communities, in their own homes.

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