Delirium vs. dementia: Compare causes, symptoms, treatments & more

By SingleCare Team | Jan. 8, 2021 Medically reviewed by Laura K. Grubb, MD, MPH

Key takeaways

Delirium is often a reversible, acute condition triggered by infections, medication, surgery, or sensory deprivation. Dementia is a progressive, persistent cognitive decline linked to neurodegenerative diseases and other factors.
Delirium affects 15%-50% of older adults during hospital stays and is most common post-surgery or in intensive care, whereas dementia affects 50 million people globally, with Alzheimer’s being the most prevalent form.
Symptoms of delirium include sudden confusion, disorientation, and memory impairment, often in response to a specific cause. Dementia develops gradually, leading to persistent memory, language, and cognitive challenges.
Treatment for delirium focuses on addressing the underlying cause and managing complications. Dementia management includes medications, lifestyle changes, and supportive therapies, with no cure currently available.

If you are caring for a loved one and start to notice a change in their mental status, such as a decline in memory or confusion, your first thought will probably be dementia. However, there could be another culprit: delirium. Sharing many of the same characteristics, these two conditions can be tricky to distinguish from one another. Let’s discuss the differences between dementia and delirium.

Causes

Delirium

“Delirium is a usually reversible alteration in mental status and/or behavioral disturbance, usually sudden in onset (but not always),” says Lili Barsky, MD, an LA-based hospitalist and urgent care physician. She explains the common causes of delirium: “It can occur in response to an infection, metabolic disturbance, intracranial structural changes, medication or toxin, sensory or sleep deprivation, surgery or hospitalization.”

Certain medications can lead to this acute confusional state, including anticholinergic and antipsychotic medications. Medical history, examinations, and lab results all help to diagnose delirium.

Dementia

One difference between delirium and dementia is that dementia usually develops over time as it is progressive in nature and it is persistent or progressing. “Dementia may be caused by neurodegenerative diseases, toxins, vascular defects, infections, autoimmune or inflammatory diseases, neurometabolic diseases, trauma, neoplasia or other structural changes in the brain,” Dr. Barksy explains.

Dementia is typically seen in older adults. There are a variety of conditions that cause dementia as well. Some common conditions include Alzheimer’s disease, dementia with lewy bodies, and Parkinson’s disease. Evidence indicates significant cognitive impairment in people with dementia.

Delirium vs. dementia causes
Delirium	Dementia
Infection, such as urinary tract infection Metabolic disturbance Intracranial structural changes Medication or toxin Sensory or sleep deprivation Surgery or hospitalization Drug toxicity	Neurodegenerative diseases Toxins Vascular defects Infections Autoimmune or inflammatory diseases Neurometabolic diseases Trauma Neoplasia or other structural changes in the brain Genetic disorders

Prevalence

Delirium

According to the Merck Manual, around 15%-50% of older people experience delirium at some time during a hospital stay. One study found that delirium was most prevalent in those who had cardiac surgery, neurosurgery, trauma, radiotherapy, and neurology patients. Intensive Care Unit (ICU) delirium, associated with an increased ICU length of stay, has a prevalence estimated at 31.8% as determined by a 2018 study.

Dementia

According to the World Health Organization, 50 million people worldwide have dementia—with 10 million new cases every year. The most common form of dementia is Alzheimer’s disease, which accounts for 60%-70% of the cases. The WHO estimates that 5%-8% of adults 60 and older have dementia.

Delirium vs. dementia prevalence
Delirium	Dementia
15-50% of older people experience delirium at some time during a hospital stay. It is most prevalent in cardiac surgery, neurosurgery, trauma, radiotherapy, and neurology patients. ICU delirium has a prevalence estimated at 31.8%.	50 million people worldwide have dementia. There are 10 million new cases every year. 60-70% of dementia cases are from Alzheimer’s disease. 5-8% of adults 60 and older have dementia.

Symptoms

Delirium

Symptoms of delirium typically have a sudden onset. They are also typically in response to a medical issue. Symptoms include:

Confusion
Disorientation
Paranoia
Hallucinations
Agitation
Somnolence
Short-term memory impairment
Problems with attention and cognition

The duration of these symptoms is variable and it is reversible.

Dementia

“While it can have many similarities in symptoms to delirium, dementia is a more progressive cognitive impairment associated with a decline in overall function, which usually develops more gradually,” Dr. Barsky says.

Symptoms of early-stage dementia usually include:

Learning and memory impairment
Difficulty concentration
Confusion with routine tasks
Word-finding issues
Mood changes
Unable to orient self to time and place, getting lost
Perceptual-motor function

It is also important to note that symptoms of dementia also vary between the conditions they accompany.

Delirium vs. dementia symptoms
Delirium	Dementia
Confusion Disorientation Paranoia Hallucinations Agitation Somnolence Short-term memory impairment	Memory impairment Difficulty concentration Confusion with routine tasks Word-finding issues Mood changes especially irritability Disorientation

Diagnosis

Delirium

“A confusion assessment method (CAM) is used to identify the presence of delirium,” Dr. Barsky explains. The CAM looks at four features:

Acute onset and fluctuating course
Inattention
Disorganized thinking
Altered level of consciousness

Delirium is diagnosed if a person has the first two features in addition to either the third or fourth feature.

Medical tests may also be performed during the diagnosis of delirium, this could include a comprehensive mental status evaluation, physical exam, laboratory studies, or brain scans to rule out other conditions, such as stroke. Additionally, it may be helpful to talk with family members or caregivers who can provide additional history and context. Laboratory tests to determine the cause of delirium such as checking various levels in the blood or urine may also be performed.

Dementia

Diagnostic tests can be used to help diagnose dementia. There are multiple tests that could be used that test cognition. Common tests are the mini-mental status examination (MMSE) or Mini-Cog assessment. These tests look at mental abilities and include the areas of memory, language, problem-solving, orientation, and other mental functioning abilities. Also, talking with family members or caregivers can provide a significant amount of information about the individual’s condition.

There are three common types of brain scans to test for dementia. They include computed tomography (CT) scans, magnetic resonance imaging (MRI), and positron emission tomography (PET) scans.

Laboratory tests like drawing blood and looking at various levels, such as electrolytes and thyroid levels, will also be performed to rule anything out, such as delirium. Genetic tests can also be a good indicator of dementia.

Delirium vs. dementia diagnosis
Delirium	Dementia
Comprehensive history and physical examination Interviews with supporting persons Confusion Assessment Method (CAM) Medical tests Laboratory testing Physical exams	Comprehensive history and physical examination Interviews with supporting persons Professional neuropsychological testing: MMSE or Mini-Cog assessment Brain imaging to identify structural changes. Laboratory testing

Treatments

Delirium

Treatment for delirium first and foremost is to find the underlying cause of delirium and address this problem. This could include treating an infection or discontinuing a medicine. Treatment will then focus on addressing any other complications and medical conditions that may have happened as a result of delirium. This could possibly include things such as providing adequate nutrition, pain management, and educating family members, caregivers, and the patient.

Dementia

As a variety of diseases can cause dementia, treatment depends on the cause. Currently, there is no cure for dementia. However, there are some drugs that may improve symptoms for some time. The two drugs approved by the U.S. Food and Drug Administration (FDA) to help treat dementia include:

Cholinesterase inhibitors: Aricept (donepezil hcl), Exelon (rivastigmine)
Memantine: Namenda Xr (memantine hcl er)

Another option is participating in clinical studies and trials for dementia. The Alzheimer’s Association has more information on possible options here.

There are many non-drug therapies, too. Memory training, cognitive exercises, social stimulation, counseling, and physical activity are just a few methods to possibly improve cognitive function.

Delirium vs. dementia treatments
Delirium	Dementia
Addressing underlying issue causing delirium Treating complications	Memory training Social stimulation Exercise Medications Clinical trials

Risk factors

Delirium

According to a 2014 study, the most common risk factors for delirium included:

Dementia
Older age
Illness severity
Visual impairment
Urinary catheterization
Low albumin level (a blood protein)
Length of hospital stay

Dementia

According to the Alzheimer’s Association the top risk factors for dementia include:

Age
Family history
Genetics
Head injury
Conditions that damage the heart

Delirium vs. dementia risk factors
Delirium	Dementia
Dementia Older age Illness severity Visual impairment Urinary catheterization Low albumin level (blood protein) Length of hospital stay	Age Family history Genetics Head injury Conditions that damage the heart

Prevention

Delirium

Prevention of delirium is done by stopping it before it starts by identifying those at highest risk.

“Individuals at highest risk of developing delirium include those with cognitive impairment, sensory or sleep deprivation, immobility, and dehydration or other underlying metabolic disturbances,” Dr. Barsky says. “Early identification and management of a medical or environmental trigger is key in preventing the development of delirium.”

Dementia

“Preventing dementia is more long-term,” Dr. Barsky continues. “There is evidence that eating healthy, staying active, avoiding tobacco and alcohol, and keeping one’s mind active with age can all help to prevent or delay the onset of dementia. It is also important to monitor blood pressure and cholesterol, as elevated levels of these can predispose to vascular dementia.”

How to prevent delirium vs. dementia
Delirium	Dementia
Prevention by identifying those with the highest risk	Healthy lifestyle Eating healthy Exercising Avoiding tobacco and alcohol Regularly monitoring blood pressure and cholesterol

When to see a doctor for delirium or dementia

The moment you see a change in mental state or cognitive decline including confusion, memory loss, disorientation, or the symptoms listed above, it is important to see a healthcare professional. Early detection for both of these conditions leads to the best outcomes.