Why Do Older Adults Get Confused? A Look at the Causes and Symptoms of Delirium

Written by Jennifer Arnouville, DO, FAAFP | Reviewed by Katie E. Golden, MD Published on June 1, 2023

Key takeaways:

• Sudden confusion in older adults is most often due to a condition called delirium. It occurs when there is another underlying medical problem.
• Delirium can be caused by many different conditions, from infection to certain medications. It will improve once that cause is identified and treated. 
• The symptoms of delirium can vary. People can be hyperactive and agitated, or they can be sleepy and listless. 

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If you have ever seen a loved one suddenly become confused, it can be a scary experience. Many times, confusion in older adults is due to a condition called delirium.

Delirium comes on fast. It causes people to act disoriented and different than their normal selves. It is very common in adults 65 years and older, and it can happen for a wide variety of reasons.

What is delirium?

Delirium is a sudden change in someone’s attention, thinking, and level of alertness. It is not a disease in itself. Rather, it is caused by an underlying medical problem that affects brain function. 

It affects older adults much more often than younger people. And in older adults, delirium may be the first symptom of a developing medical problem. For example, someone with a UTI (urinary tract infection) may become confused instead of having the usual symptoms like burning or frequency. 

Delirium can be serious. It is associated with increased risks for long-term disability and death. People who have experienced delirium can have significant anxiety during and following the episode. Sometimes, this leads to post-traumatic stress disorder (PTSD). Delirium also increases the risk for later development of dementia. 

How can you tell if an older adult has delirium?

Delirium looks like an unexpected change in someone’s usual mental clarity and behavior. People who have witnessed delirium often describe their loved ones as being “out of it” or “not themselves.” The change can come on quickly, in a matter of minutes. Or it may be a change that comes on more slowly over hours or days. 

Common symptoms and behaviors of delirium include:

• Confusion: People with delirium may be more forgetful. They may become disoriented and lose track of the time or where they are. They may not recognize familiar people.
• Agitation: Delirium can cause people to yell or cry out. They may hit, bite, or try to get away. This can also lead to an increased risk of injury and falling. 
• Hallucinations:Hallucinations are when someone sees or hears something that is not there. So, someone with delirium may appear delusional.
• Paranoia: People with delirium can sometimes become fearful and paranoid. They may resist any attempt to help. Or they may accuse caregivers of doing things like stealing. 
• Lethargy: Delirium can also cause people to feel more tired and to doze off more easily than usual. 
• Inattention:Someone with delirium will have trouble following commands and conversation. A good test for inattention is to ask someone to say the days of the week backward. 

Delirium can easily be confused with other conditions that are also common in older adults. But there are ways that can help you tell the difference between delirium and other conditions like:

• Dementia: Unlike delirium, the symptoms of dementia usually come on gradually over a longer period of time, like weeks to months.
• Stroke: A stroke can cause sudden onset confusion, and it can look a lot like delirium. But many times, it will usually have other neurologic symptoms. Examples include drooping of the face, one-sided weakness or numbness, and garbled speech. 
• Psychosis: Schizophrenia and other mental health conditions can cause confusion, hallucinations, paranoia, and agitation. In older adults, they will often have a prior history of a mental health disorder if this is the explanation. 

The top 6 causes of delirium

Delirium can be caused by any underlying medical problem that affects brain function. However, a few causes account for the majority of hospitalizations for delirium: 

1. Infection: This is the most common cause for delirium, especially UTI, pneumonia, and sepsis. But any infection can potentially lead to delirium.
2. Medications: Sedatives and opioids are common culprits, but there are several drugs that can be risky for older adults.
3. Dehydration: Not drinking enough water is a common cause of hospitalization and delirium for older adults. This is especially the case if the dehydration leads to high sodium levels. 
4. Electrolyte imbalance: Low sodium levels can also lead to delirium. So can high calcium levels. 
5. Surgery: Delirium is a common complication of surgery. It happens in up to 25% of all surgeries, and in up to half of major surgeries such as cardiac or orthopedic surgeries. 
6. Hospitalization: Similar to surgery, being in the hospital is highly linked with delirium. Stress and interrupted sleep are thought to contribute.

Just knowing the top reasons for delirium can help prevent it from happening in the first place. For example, you may be able to decrease the risk of delirium if:

• You start treatment early for any signs of infection.
• You avoid or minimize medications that are more likely to cause delirium. 
• Caregivers help their older loved ones stay nourished and hydrated. 
• Hospitalizations and surgeries are only pursued when absolutely necessary. 

When does someone with delirium need to go to the hospital?

You should seek medical help any time an aging parent or loved one is experiencing symptoms of delirium. However, this does not always mean a trip to the emergency room (ER) or hospital is necessary. Many times, a primary care provider can help treat the problem. 

Some cases require more urgent attention. The following are signs of a possible serious problem where ER care is needed:

• Any sign of stroke, including drooping face, garbled speech, inability to speak, sudden weakness, or discoordination
• Extreme agitation, especially if you have safety concerns 
• Headache
• Severe pain of any kind
• Loss of consciousness or inability to stay awake
• Difficulty breathing
• Fever, or other signs of infection

The bottom line

Seeing a loved one experience confusion for any reason can be a scary and stressful experience. But delirium is generally reversible. This means it will improve once the underlying cause is treated. If you are a caregiver, understanding what causes delirium and how to recognize it can make a big difference in your loved one’s care. The best rule to follow is that any person who becomes abruptly confused or has major changes in thinking or behavior needs urgent medical attention.