Delirium vs dementia in older adults

What are cognitive disorders?

Cognitive disorders are a collection of conditions that impair the cognitive function of a person, such as their memory, thinking abilities and reasoning skills. Some examples of thesedisorders or underlying reasons for cognitive declinemight include things like:

• Dementia
• Delirium
• Medication side effects
• Metabolic and/or endocrine dysfunction
• Illness (such as urinary tract infections or COVID-19)
• Depression 

It is crucial to understand the underlying causes of cognitive difficulties in order to effectively treat or manage them, and dementia and delirium are two incredibly important disorders to identify promptly. Both can cause similar symptoms, such as memory loss or judgement difficulties, so often they are misdiagnosed or misunderstood. In most cases they can be differentiated because dementia is characterised by gradual decline of cognitive abilities, whereas delirium is characterised by a temporary state of confusion and disorientation. Although this can help to tell them apart, it is not always easy to do so. Both disorders are prevalent in older adults due to common age-related changes in the brain. In older adults, there is an increased risk of neurological disorders alongside other health issues such as infections or medication side effects, so cognitive disorders are incredibly important to identify in this age group in order to either treat or manage ongoing symptoms effectively with the help of caregivers. While it is difficult to ascertain how common cognitive disorders are in older adults, an estimated 10-20% of those with Mild Cognitive Impairment (MCI) aged 65 or older will develop dementia over a one-year period, but it is important to remember not everyone with MCI will develop this. Studies have identified that in many cases, doctors may be unaware of cognitive impairment in over 40% of patients who are showing signs of this. Any type of cognitive disorder can impact an older person’s caregivers too, as they may not be acting like themselves and could display behaviours that are unusual or even dangerous to themselves or others, leading to a need for full-time care.

What is dementia?

Dementia is a collective term describing a number of progressive neurological disorders that impair cognitive function. Unlike the sudden nature of delirium, this is categorised by progressive onset over several years. The condition causes symptoms such as:

• Memory issues 
• Communication issues 
• Diminished reasoning and decision making skills 
• Reduced ability to perform daily activities
• Struggling to perform basic tasks
• Mood and personality changes

You can learn more about the different types of dementia and how it progresses in our guides to the different types of dementia and managing the stages of dementia.

How does dementia differ from delirium?

Studies define dementia as a neurodegenerative disorder with various subtypes primarily affecting older adults, while delirium is thought to be a symptom that can occur in any age group (although more commonly in older adults). Both happen to present with similar symptoms, but there are several key differences to help medical professionals and caregivers differentiate between the two, including: 

Speed of onset

One of the most important differences between dementia and delirium is the speed of onset, with dementia symptoms developing slowly over several years, and delirium developing quickly, sometimes over a few hours or days. 

Symptom identification

Often a person with dementia will show only mild symptoms in the beginning that may not be noticeable to loved ones, however delirium is usually much more noticeable to those around the person, as their behaviours can change drastically from how they usually act. Also, memory loss is one of the most common symptoms of dementia, but this may not happen in those with delirium.

Symptom fluctuation

For a person with dementia, their symptoms will typically remain constant throughout the day, with a gradual decline in abilities over several years. In delirium, symptoms can fluctuate drastically throughout the day.

Length of symptoms

Delirium can last for just a few days, weeks or months before improvements are noticed (if the condition is curable), while dementia will get progressively worse over time, not better. 

Communication issues

A person with dementia may struggle to find the right words or put sentences together to explain what they need, whereas a person with delirium may be able to say full words and sentences, but could be saying things that are out of character for them or don’t make logical sense. 

Underlying cause

The cause of dementia is largely dependent on the type of dementia a person has, and different types of dementia are caused by specific changes in the brain that damage neurons, leading to electrical messages not being efficiently sent across those neurons. This can negatively impact certain functions of the body, which get progressively worse over time until they start to affect day-to-day life. Conversely, delirium is typically a symptom caused by underlying medical issues such as urinary tract infections, pneumonia, severe dehydration, or a reaction to a specific medication, and is not a condition in itself. 

Risk factors

Old age is the most common risk factor for dementia, being most prevalent in those over 65 years old, but also in those who smoke, eat a poor diet and do not exercise. Delirium is also most likely to occur in older age groups, but can be caused by a number of other conditions for which the risk factors may be high or low depending on the individual. 

Curability

Dementia cannot be cured, so it is considered a terminal condition. Delirium, on the other hand, is an acute condition usually caused by medical issues that may or may not be as life-threatening as dementia, and could be cured. 

Preventability

Dementia is considered unpreventable, however some scientists believe the symptom development of dementia could be slowed with cognitive exercises and stimulation. Delirium could be prevented with some simple lifestyle changes depending on the underlying condition. For example, if infection is the cause, early detection will help to avoid delirium. 

Can dementia be influenced by delirium?

A person with dementia may also experience a co-occurring condition that causes delirium, and both dementia and delirium can coexist in older adults, particularly if the person’s dementia is rapidly progressive. Individuals with dementia are at a higher risk of developing delirium due to the fact that their cognitive function is already compromised, and delirium can exacerbate dementia symptoms in some cases, with studies finding that it can lead to adverse outcomes like the acceleration of cognitive decline in those with dementia.Diagnosing either condition can be difficult with the potential symptom overlap, so it is best (and potentially life-saving) to seek medical advice as soon as possible if symptoms of either condition are present. Medical professionals may find it difficult to distinguish between delirium and dementia, and this is made even more challenging when someone already has dementia and may be displaying signs of delirium. One study found those with delirium had a 39% higher risk of death, and a 3x higher risk of being diagnosed with dementia than those without delirium, so it is important to seek treatment as soon as possible for both conditions. Untreated delirium can have both immediate and long-term impacts on cognitive health, and depending on the underlying condition, this could be fatal. 

How are dementia and delirium treated or managed?

Diagnosing dementia or delirium involves different tests and assessments that typically involve evaluations of cognitive function and brain imaging. 

Treating dementia 

Dementia assessments may take several weeks due to attendance at memory clinics and the input from several different types of doctors. The National Institute for Health and Care Excellence says diagnosis of dementia typically involves initial assessments to understand certain aspects of the person’s character and behaviours. They may ask about their medical history, their current level of cognition and function relative to whatever is considered to be their base level, questions about the impact symptoms have on their daily activities, discussions about any cognitive, behavioural or psychological changes, assessments for coordination abnormalities, sensory issues, motor symptoms, visual or auditory issues, cardiovascular signs, other causes of symptoms, and more. There is no cure for dementia, but treatments can be focused on managing the symptoms and promoting quality of life. This can be done with the help of medications, therapy sessions, medical support, home adaptations, and lifestyle modifications such as a healthy diet and getting regular exercise, which studies have found could help slow cognitive decline.

Treating delirium 

Delirium usually requires a fast assessment of symptoms to catch the underlying cause as soon as possible, and these tests will focus on other symptoms that may be present. For example, if an infection is suspected, diagnosis will focus on this. Medical professionals will use their expertise and prior knowledge of the progression of symptoms to determine which tests will be most appropriate for the symptoms the person is presenting with. Depending on the underlying condition found, delirium as a symptom can usually be cured, and this may be quick or could take time. For example, if severe dehydration is the cause, an older adult could undergo fast-acting treatment in hospital to replenish their fluids and diminish delirium. Or, if an infection is the cause, a longer-term regime of antibiotics or another treatment may be required, which could take several days or weeks to see results. If an older adult has experienced long-term delirium, they may still have issues with their memory and thinking skills in the weeks or months after their initial illness, and this is common in older adults with delirium who are recovering from a major operation.Steps can also be taken to prevent this happening in future, with studies suggesting delirium may be preventable in 30-40% of cases. 

Can home care help with dementia or delirium? 

Home care can have a significantly positive impact on both dementia and delirium by providing personalised, continuous support in a familiar environment that is likely to not cause any additional stress for the person. In the case of dementia, home care can offer assistance with daily activities, medication management, cognitive stimulation such as dementia-friendly games, maintaining routines, reducing stress, and more. Caregivers can also monitor for changes in health and the person’s behaviours, and provide early intervention if their symptoms worsen. With delirium, home care may be more of a temporary arrangement, but this can help to provide consistency of care, ensure a calm, structured environment, and reduce confusion and agitation. Caregivers may even be able to address underlying causes such as dehydration or infections, but attention from a medical professional is crucial regardless of interventions from caregivers. If you are caring for someone with dementia or someone who is experiencing delirium as a symptom, home care could be a great support for you and your family by providing specialist dementia care, respite care for when you need a break, or by helping to identify any changes in symptoms that require medical attention. At Home Instead, our approach to dementia care is pioneering, and we have developed a unique programme for Care Professionals accredited by City & Guilds that is specialised for the home care environment, and created by dementia specialists and key medical practitioners from around the world. We’re an award-winning home care provider and part of a worldwide organisation devoted to providing the highest-quality relationship-led care for older people in their own homes. Arranging care for yourself or your loved one shouldn’t be stressful, so whatever questions you would like answered, feel free to reach out to the Home Instead team to discuss your needs.