Pop quiz: What aging health problem is extremely common, has serious implications for an older person’s health and wellbeing, and can often – but not always – be prevented?

It’s delirium. In my opinion, this is one of the most important aging health problems for older adults to be aware of. It’s also vital for family caregivers to know about this condition, since families can be integral to preventing and detecting delirium.

In this article, I’ll explain just what delirium is, and how it compares to dementia. Then I’ll share 10 things you should know, and what you can do.

What is Delirium

Delirium is a state of worse-than-usual mental confusion, brought on by some type of unusual stress on the body or mind. It’s sometimes referred to as an “acute confusional state,” because it develops fairly quickly (e.g., over hours to days), whereas mental confusion due to Alzheimer’s or another dementia usually develops over a long time.

The key symptom of delirium is that the person develops difficulty focusing or paying attention. Delirium also often causes a variety of other cognitive symptoms, such as memory problems, language problems, disorientation, or even vivid hallucinations. In most cases, the symptoms “fluctuate,” with the person appearing better at certain times and worse at other times, especially later in the day.

Delirium is usually triggered by a medical illness, or by the stress of hospitalization, especially if the hospitalization includes surgery and anesthesia. However, in people who have especially vulnerable brains (such as those with Alzheimer’s or another dementia), delirium can be provoked by medication side-effects or less severe illnesses.

It’s much more common than many people realize: about 30% of older adults experience delirium at some point during a hospitalization.

That confusion after surgery that older adults often experience? That’s delirium.

The way your elderly mother with dementia gets twice as confused when she has a urinary tract infection? That’s delirium too.

Or the common phenomenon of “ICU psychosis”? That too is delirium.

What Causes Delirium?

In older adults, delirium often has multiple causes and contributors. These can include:

• Infection (including UTI, pneumonia, the flu, COVID)
• Other serious medical illness (e.g. heart attack, kidney failure, stroke, and more)
• Metabolic imbalances (e.g. abnormal blood levels of sodium, calcium, or other electrolytes)
• Dehydration
• Medication side-effects
• Sleep deprivation
• Uncontrolled pain
• Sensory impairment (e.g. poor vision and hearing, which can worsen if the person is lacking their usual glasses or hearing aids)
• Alcohol withdrawal

Delirium vs. Dementia

People often confuse delirium and dementia (such as Alzheimer’s disease), because both conditions cause confusion and appear superficially similar. Furthermore, people with dementia are actually quite prone to develop delirium. That’s because delirium is basically a reflection of the brain going haywire when it gets overloaded by the stress of illness or toxins, and brains with dementia get overloaded more easily.

In fact, the more vulnerable a person’s brain is, the less it takes to tip them into delirium. So a younger person generally has to be very very sick to become delirious. But a frail older person with Alzheimer’s might become delirious just from being stressed and sleep-deprived while in the hospital.

Why Delirium is Such an Important Problem

There are three major reasons why delirium is an important problem for us all to prevent, detect, and manage.

First, delirium is a sign of illness or stress on the body and mind. So if a person becomes delirious, it’s important to identify the underlying problems – such as an infection or untreated pain – and correct them, so that the person can heal and improve.

The second reason delirium is important is that a confused person is at higher risk for falls and injuries during the period of delirium.

The third reason is that delirium often causes serious consequences related to health and well-being.

In the short term, delirium increases the length of hospital stays, and has been linked to a higher chance of dying during hospitalization. In the longer term, delirium has been linked to worse health outcomes, such as declines in independence, and even acceleration of cognitive decline.

Now let’s cover 10 more important facts you should know about delirium, especially if you’re concerned about an aging parent or other older relative.

10 Things to Know About Delirium, and What You Can Do

1.Delirium is extremely common in aging adults.

Almost a third of adults aged 65 and older experience delirium at some point during a hospitalization, with delirium being even more common in the intensive care unit, where it’s been found to affect 70% of patients. Delirium is also common in rehabilitation units, with one study finding that 16% of patients were experiencing delirium.

Delirium is less common in the outpatient setting (e.g. home, assisted-living, or primary care office). But it still can occur when an older adults gets sick or is affected by medications, especially if the person has a dementia such as Alzheimer’s.

What to do: Learn about delirium, so that you can help your older loved ones reduce the risk, get help quickly if needed, and better understand what to expect if someone does develop delirium. You should be especially be prepared to spot delirium if your parent or loved one is hospitalized, or has a dementia diagnosis. Don’t assume this is a rare problem that probably won’t affect your family. For more on hospital delirium, see Hospital Delirium: What to know & do.

2. Delirium can make a person quieter.

Although people often think of delirium meaning as a state of agitation and or restlessness, many older delirious people get quieter instead. This is called hypoactive delirium. It’s still linked with difficulty focusing attention, fluctuating symptoms, and worse than usual thinking. It’s also linked with poor outcomes. But it’s of course harder for people to notice, since there’s little “raving” or restlessness to catch people’s attention.

What to do: Be alert to those signs of difficulty focusing and worse-than-usual confusion, even if your older person seems quiet and isn’t agitated. Tell the hospital staff if you think your relative may be having hypoactive delirium. In the hospital, it’s normal for older patients to be tired. It’s not normal for them to have a lot more difficulty than usual making sense of what you say to them.

3. Delirium is often missed by hospital staff.

Despite the fact that delirium is extremely common, it is often missed in hospitalized older adults, with some reports estimating it’s being missed 70% of the time. That’s because busy hospital staff will have trouble realizing that an older person’s confusion is new or worse-than-usual. This is especially true for people who either look quite old – in which case hospital staff may assume the person has Alzheimer’s – or have a diagnosis of dementia in their chart.

What to do: You must be prepared to speak up if you notice that your family member isn’t in his or her usual state of mind. Hypoactive delirium is especially easy for hospital staff to miss. Hospitals are trying to improve delirium prevention and detection, but we all benefit when families help out. Remember, no hospital person knows your older person the way that you do.

4. Delirium can be the only outward sign of a potentially life-threatening problem.

Although delirium can be brought on or worsened by “little things” such as sleep deprivation or untreated constipation, it can also be a sign of a very serious medical problem. For instance, older adults have been known to become delirious in response to urinary tract infections, pneumonia, and heart attacks.

In general, it tends to be older persons with dementia who are most likely to show delirium as the only outward symptom of a very serious medical illness. But whether or not your older relative has dementia, if you notice delirium, you’ll want to get a medical evaluation as soon as possible.

What to do: Again, if you notice new or worse-than-usual mental functioning, you must bring it up and get your older loved one medically evaluated without delay. For older adults who are at home or in assisted -living, you should call the primary care doctor’s office, so that a nurse or doctor can help you determine whether you need an urgent care visit versus an emergency room evaluation.

5. Delirium often has multiple underlying causes.

In older adults with delirium, we often end up identifying several problems that collectively might be overwhelming an older person’s mental resilience. Along with serious medical illnesses, common contributors/causes for delirium include medication side effects (especially medications that are sedating or affect brain function), anesthesia, blood electrolyte imbalances, sleep deprivation, lack of hearing aids and glasses, and uncontrolled pain or constipation. Substance abuse or withdrawal can also provoke delirium.

What to do: To prevent delirium, learn about common contributors and try to avoid them or manage them proactively. For instance, if you have a choice regarding where to hospitalize an older person, some hospitals have “acute care for elders” units that try to minimize sleep deprivation and other hospital-related stressors. If your older relative does develop delirium, realize that there is often not a single “smoking gun” when it comes to delirium. A good delirium evaluation will attempt to identify and correct as many factors as possible.

6. Delirium is diagnosed by clinical evaluation.

To diagnose delirium, a doctor first has to notice – or be alerted to – the fact that a person may not be in his or her usual state of mind. Experts recommend that doctors then use the Confusion Assessment Method (CAM), which describes four features that doctors must assess. Delirium can be diagnosed if a patient’s symptoms include “acute onset and fluctuating course,” “difficulty paying attention,” and then either “disorganized thinking” or “altered level of consciousness.”

Delirium cannot be diagnosed by lab tests or scans. However, if an older adult is diagnosed with delirium, doctors generally should order tests and review medications, in order to identify factors that have caused or worsened the delirium.

What to do: Again, the most important thing for you to do is to get help for your loved one if you notice worse-than-usual confusion or difficulty focusing. Although families have historically not had a major role in delirium diagnosis, delirium experts have developed a family version of the CAM (FAM-CAM), which is designed for non-clinicians and has been shown to help detect delirium.

7. Delirium is treated by identifying and reversing triggers, and providing supportive care.

Delirium treatment requires a care team to take a three-pronged approach.

1. Health providers must identify and reverse the illness or problems provoking the delirium.
2. They have to manage any agitation or restless behavior, which can be tricky since a fair number of sedating medications can worsen delirium.
   1. The safest approach is a reassuring presence (family is best, but hospitals sometimes also provide a “sitter”) to be with the person, plus improve the environment if possible (e.g. a room with a window and natural light).
   2. The once-popular practice of physically restraining agitated older adults has been shown to sometimes worsen delirium, and should be avoided if possible.
3. The care team needs to provide general supportive care to help the brain and body recover.

What to do: The reassuring presence of family is often key to providing a supportive environment that promotes delirium recovery. You can also help by making sure your loved one has glasses and hearing aids, and by alerting the doctors if you notice pain or constipation. Ask the clinical team how you can assist, if restlessness or agitation are an issue. Bear in mind that physical restraints should be avoided, as there are generally safer ways to manage agitation in delirium.

8. It can take older adults a long time to fully recover from delirium.

Most people are noticeably better within a few days, once the delirium triggers have been addressed. But it can take weeks, or even months, for some aging adults to fully recover.

For instance, a study of older heart surgery patients found that delirium occurred in 46% of the patients. After 6 months, 40% of those who had developed delirium still hadn’t recovered to their pre-hospital cognitive abilities.

What to do: If your parent or someone you love is diagnosed with delirium, don’t be surprised if it takes quite a while for him or her to fully recover. It’s good to be prepared to offer extra help during this period of time. You can facilitate recovery by creating a restful recuperation environment that minimizes mental stress and promotes physical well-being.

9. Delirium has been associated with accelerated cognitive decline and with developing dementia.

This is unfortunate, but true, especially in people who already have Alzheimer’s or another type of dementia. A 2009 study found that in such persons, delirium during hospitalization is linked to a much faster cognitive decline in the following year. A 2012 study reached similar conclusions, estimating that cognition declined about twice as quickly after delirium in the hospital.

In older adults who don’t have dementia, studies have found that delirium increases the risk of later developing dementia.

What to do: Experts aren’t sure what can be done to counter this unfortunate consequence of delirium, other than to try to optimize brain well-being in general. (For this, I suggest avoiding risky medications, getting enough exercise and sleep, being socially and intellectually active, and avoiding future delirium if possible; learn more here.)

The main thing to know is that delirium has serious consequences, so it’s often worth it for a family to be careful about surgery in an older person, and it’s good to learn about delirium prevention (see below).

10. Delirium is preventable, although not all cases can be prevented.

Experts estimate that delirium is preventable in about 40% of cases. Preventive strategies are meant to reduce stress and strain on an older person, and also try to minimize delirium triggers, such as uncontrolled pain or risky medications.

In the hospital setting, programs such as the Hospital Elder Life Program (HELP) for Prevention of Delirium have been shown to work. For ideas on how families can help, see this family tip sheet from the Hospital Elder Life Program. For instance, families can help reorient a relative in the hospital, ensure that glasses and hearing aids are available, and provide a reassuring presence to counter the stress of the hospital setting.

Less is known about preventing delirium in the home setting. However, since taking anticholinergic medications (such as sedating antihistamines) has been linked with hospitalizations for confusion, you can probably prevent delirium by learning to spot risky medications your parent might be taking.

What to do: To prevent hospital delirium, carefully weigh the risks and benefits before proceeding with elective surgery. If your older loved one must be hospitalized, choose a facility using the HELP program or with an Acute Care for Elders unit if possible. Be sure to read HELP’s tips for families on preventing hospital delirium.

Remember, delirium is common and can be the only outward sign of a serious medical problem.

By educating yourself and helping your older loved ones be proactive about prevention, you can reduce the chance of harm from this condition.

And if you do notice symptoms of delirium, make sure to tell the doctors! This will help your parent get the evaluation and treatment that he or she needs.

Useful Online Resources Related to Delirium

Here are links to some of the resources I reference in the article:

• A study (one of many) finding that delirium is linked to worse health outcomes in the elderly
• A study of older adults in the Intensive Care Unit, finding that 43.5% had hypoactive delirium
• An article finding that older patients do better when they are hospitalized in an “Acute Care for Elders” unit (a special hospital ward tailored towards protecting older adults from hospital complications; they are great!)
• An explanation of the Confusion Assessment Method, which experts recommend doctors use to diagnose delirium
• A description of the Family-CAM, which experts developed to help family caregivers detect delirium
• A study finding that delirium accelerates cognitive decline in Alzheimer’s; a follow-up study finding that people with dementia decline twice as quickly after having delirium (!) is here.
• Tips on how family caregivers can prevent delirium, from the Hospital Elder Life Program

Last but not least, for my previous posts on delirium:

• Delirium: How Caregivers Can Protect Alzheimer’s Patients
• Hospital Delirium: What to Know and Do
• How to Maintain Brain Health: the IOM Report on Cognitive Aging

This article was reviewed and updated in January 2025.